january, 1960 - American Radio History

january, 1960 - American Radio History
JANUARY, 1960
Covering all
phases of..
II!
0
TECHNICAL JOURNAL OF THE BROADCAST INDU
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TAPE GROWS IN USE BY BROADCASTERS
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CEnter 9 -6100
THE TECHNICAL JOURNAL OF THE BROADCAST INDUSTRY
VOLUME 2
JANUARY, 1960
NUMBER
1
t:DITORIAL
E. ME11L, Editor
II. F. PAnet)URT, Managing Editor
DUDLEY U' E, Presentation Editor
E. P. LANGAX, Advertising Director
S. F. WII.SI 'N, l'roductinn Manager
W. J. SHAW, Circulation Director
I
Contents
Sub -Carrier
Generation
in
Multiplex Exciters
Application of
Synthetic Reverberation Systems
6
The Development and
The Effects of Transmitter Sound Power
Reduction on Receiver Performance
8
ADVERTISING SALES OFFICES
Flushing 54, New York
PAUL AND I II IX WEI1.
:tn -ill Main Sheet
Telephone INdependence 3 -9(98
14
Stereophonic Broadcast Experiments at KISW -FM
18
The Role of Tape in Radio's Rise
20
Professor Snikrah
.
Chicago
5.
Illinois
\\'11.1.1.1\1 L. MIl l,F:It. Alt.
E. F. l.l'I:ENS
307 X. Michigan Ave.
Telephone Fltanklin 2-7044
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DAVID H. HEIt'l'El.
3loo Wooster Itnod
Telephone El Pisan -23h.
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22
Southwest
II. ST(1CKWEI.I. Co.
W. lath Street
C.
4911í
J1is -intt. Kansas
Telephone It:\ndolph 2-1117
Los Angeles 57, California
Departments
Amendments and Proposed Changes of
F.C.C. Regulations
Industry News
11:\t'Itl('I:
A. KIMI::\I,l,
ert I:ou leca rd
Telephone 111'okirk 8 -GI78
San Francisco 5, California
28
37
\l'Itll't:
:1[:
681
39
40
Classified Ads
40
Index to Advertisers
40
8,
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*
Cover
James F. Zimmerle (left) and Jay F. Graves of radio station KOA in
Denver are shown operating the recording system which is used to
provide continuous network delay. The importance of magnetic recording in today's broadcasting is pointed out in the article on page 20.
Subscription Price: U. S. $6, one year; Outside U. S. A., 67. Single copies. 75 cents.
Adjustments necessitated by subscription
termination at single copy price.
is published niontily by
Technical Publications, Inc.. 1014 Wyandotte St..
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Itroadcast Engineering
Corporate Personnel: Robert E. Hertel. President; Frank D. Smalley. Executive Vice- President: E. I'. Langan, Vice -President; -X. J.
Shaw, Vice- lresident: Kenneth Long, Vice l'resldent; D. E. Mehl, Vice- President.
January. 1960
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separate power supply accepts line voltage in the range of 110 to 240
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A
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Range: 30
15000 cps.
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Sensitivity (200 ohms):
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The Type
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TECHNICAL DATA
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Impedance: monaural 800 ohms, stereo
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Frequency range: 40
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January, 1960
STAMFORD, CONNECTICUT
3
The central control panel of the RCA TV Tape
Recorder puts all operating controls at your fingertips.
Major control features are illustrated on the panel,
zoned in 15 areas as follows: (1) Variable Speed
Rewind; (2) Single Control Playback; (3) Independent
Control of Video, Audio and Cue Record; (4) Local Remote Operation; (5) Automatic Shoe Position
Control; (6) Capstan Speed Control; (7) Video Head
Current Indication; (8) Multi -Purpose Meter/Speaker
Selector; (9) Independent Audio /Cue Record and
Playback Level Controls; (10) Built -In Monitoring
Speaker, and Speaker Volume Control; (11) Master
Erase Current Meter; (12) Control Track Current
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ASK ABOUT THE OTHER VITAL REASONS WHY IT PAYS TO "TAPE IT RCA "!
ANOTHER WAY
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BROADCASTERS
THROUGH
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features
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RCA TV TAPE
CONTROL CENTRAL
All operating controls on
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Variable Speed Rewind
Fast forward, fast reverse. Rewinds 90 minute reel in 4%
minutes. Rapid cue any point on tape. Tape speed can be
varied until audio or cue channels become intelligible.
a
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Independent Audio /Cue Record and
Playback Level Controls
Built -In Monitoring Speaker, and Speaker
Volume Control
button activates playback functions. Automatically stops at the end of the tape. A stop button is proA single push
For monitoring audio or cue channel input, record or playback output. Built -in RCA BA -24 Broadcast Monitoring
Amplifier will also drive external speaker.
A
Erase Current Meter
m Mastermaster
erase circuit operating by indicating current
Local- Remote Operation
® Control Track Current Meter
current
set -up switch activates all electronics, placing the recorder
in operation without running tape through. This enables
operators to checkout circuitry prior to recording or playback.
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17" panel!
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vided for manual operation.
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Standard RCA broadcast audio amplifiers associated with
Single Control Playback
Independent Control of Video, Audio and
Cue Recording
single
Selector switch delegates basic record /playback functions
for local or remotely controlled operation.
Automatic Shoe Positioning
The tape shoe position is automatically controlled during
playback to prevent skewing effects. In the record mode,
operation is electrically switched to manual- head -to-tape
pressure can be adjusted using calibrated dial.
Capstan Speed Control
Manual override of normal operating speed to permit synchronization of two machines.
Video Head Current Indication
Switchable to indicate recording current in each of the four
heads or total current in the head assembly. Permits quick
diagnosis of performance during recording.
Multi- Purpose Meter /Speaker Selector
Provides instantaneous check of input, record and play
functions, and erase in either audio or cue channels.
Shows
in master erase head.
e
is
Provides continuous indication of
track head.
in servo-control
Control Track Phase Adjustment
Dual control provides coarse and vernier adju-t.ments.
Coarse adjustment is for slipping any of the four heads on
to any given recorded track. Vernier adjustment is for centering the heads precisely on that track.
Head Hour Meter
Indicates number of hours on video heads during actual
recording and playback.
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For locking equipment to power line or local sync generator.
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RADIO CORPORATION of AMERICA
BROADCAST AND TELEVISION EQUIPMENT
CAMDEN, N.
J.
SUB -CARRIER GENERATION
Part
By
DWIGHT "RED" HARKINS*
2
of
a
discussion of the methods used to
generate frequency modulated sub- carriers for subsidiary
communications services in FM broadcasting.
LAST month we outlined the different systems of producing a sub -carrier by the heterodyne method. Now
let's turn our attention to several interesting methods of producing a
frequency modulated sub -carrier by
direct methods.
First, we shall outline a procedure
that is used to produce frequency
modulation of an oscillation at 65
Kc. The oscillating circuit consists
of several triodes in cascade which in
turn are connected to feed the out put back into the input in what we
shall refer to as a ring oscillator.
This name comes from the fact
that it is a "ring around a rosie" circuit and is nothing more nor less
than an audio amplifier connected
up in such a way that it becomes an
oscillator. This is not uncommon in
building amplifiers which are not intended to oscillate.
In this case the plate loads and
coupling condensers between the
stages are chosen so that the oscillation occurs at the desired frequency
of, let's say, 65 Kc. A total phase
shift of 720 degrees occurs.
Referring to Figure 1, we see a
group of triode audio amplification
stages connected in a circle so that
the whole thing oscillates. Now if
anything in the oscillating circle
changes, the frequency will change.
In order to produce a frequency
modulated signal, it is only necessary
to apply a changing reactance to the
grids of each of the tubes in the
oscillating circle.
In Figure 2, we see a simple reactance tube circuit which is applied
to the grid of each of the triodes in
the ring.
Applying audio to each of the reactance tubes simultaneously causes
a change in the oscillating circuit
that is directly related to the audio.
The audio voltage controls the frequency of the whole oscillating array,
therefore producing a frequency
modulated signal.
This system has excellent center
frequency stability but is limited as
to the amount of frequency deviation that can be produced. Audio
frequencies below 1,000 cycles will
easily produce a deviation of plus or
minus 5 Kc. Certain peculiarities of
the circuit, however, cause the higher
audio frequencies to produce in addition to a deviation of the center frequency, unusual distortion components. It has been noted that the ap-
plication of a tone of 5,000 cycles,
for example, produces in addition to
a frequency modulation of a center
carrier an amplitude modulation
component which is large enough to
cause distortion in the receiver. Our
development of this unique circuit
was discontinued when it appeared
that too many components would be
required in order to obtain the necessary degree of deviation required
for all applications of multiplexing.
Another interesting but as yet not
commercially used application of the
direct frequency modulated oscillator
is the positive biased multi- vibrator.
This circuit as shown in Figure 3,
makes possible the frequency modulated sub -carrier to be produced
from a multi- vibrator. Audio voltage causes the multi -vibrator to deviate in accordance with the amplitude of the applied audio voltage.
This circuit was invented by Mr.
E. H. B. Bartelink. The original application was for the purpose of
creating sub -carriers in the range of
100 to 400 Kc. using frequency modulation which in turn could be applied to open wire telephone lines for
the purpose of allowing several audio
communication circuits over one pair
of lines.
720' phase shift
r
T
REACTANCE
TRIODE
TRIODE
REACTANCE
TUBE
TUBE
TRIODE
REACTANCE
TUBE
AUDIO MODULATING VOLTAGE
Figure I.
6
Block diagram of ring oscillator which is used to produce frequency
modulation of an FM multiplex sub -carrier.
This circuit was used in our very
first sub -carrier generator used in
1055. Although capable of excellent
frequency modulation in the lower
audio frequencies, it was not found
to have low enough distortion and
ample frequency response characteristics to use for the transmission of
music. For the purpose of generating
a sub -carrier that is to be used for
voice communication only, however,
it remains the simplest and most
straight forward method possible.
In summing up the various meth'Harkins Radio, Inc.,
4444
East Washington St.,
Phoenix, Ariz,
BROADCAST ENGINEERING
TO GRID OF PHASE SHIFT
OSCILLATOR TUBE
11
Figure 2.
_.
Diagram of rectance tube circuits which applies the audio signal to
the ring oscillator.
ods of producing a sub -carrier, we
have:
(A) HETERODYNE METHODS
1.
2.
3.
AUDIO
VOLTAGE
Reactance tube controlled high frequency oscillator heterodyned
with a crystal oscillator to produce the desired sub-carrier center
frequency.
(This system requires automatic
center frequency control)
Crystal controlled phase modulators which after considerable multiplication are heterodyned with a
fixed oscillator to produce the
desired sub -carrier.
Reactance tube controlled low frequency oscillator capable of 25 Kc.
deviation and carrier stability that
does not require automatic frequency control.
high degree of multiplication, the
generator unit will have circuits that
are operating on many frequencies
between 100 Kc. and 28.8 Mc. If, for
example, the second doubler of the
multiplier string happens to hit a
frequency of 920 Kc. which is the
same frequency of the AM station
where the unit is installed, some very
serious interference results. In our
experience throughout the country,
we have run into several cases where
our units had to be redesigned so
that the multipliers missed the frequency of equipment on the same
premises. If the sub -carrier generator
had only the fundamental tc contend with, no interference of this nature would ever be encountered.
Another problem with the nultiplier type of sub -carrier generator is
that various frequencies present in
the sub- carrier generator have on
occasion leaked into the FM exciter
which is also full of multiplier; with
the result that some of the frequencies are too close to each other which
in turn produces interference. As
another example, we cite the case
where a sub- carrier generator uses a
100 Kc. master crystal while tF e FM
transmitter uses a master crystal
close to 100 Kc. If any of the 100
Kc. present in the sub -carrie generator leaks into the main FM transmitter, all sorts of peculiar phenomena will result.
The purpose of this article is to
review all of the various methods
possible that can be used for generation of a sub- carrier and to point out
the desirability of future development of the simplest possible generator that will produce the necessary
deviation without distortion and amplitude modulation by-products. Going back to the classic illustrarion of
FM, it would be ideal if a 65 Kc.
oscillator could be deviated by a con densor microphone sufficiently to
produce a swing of plus or minus 10
Kc. This would be the ideal si b -carrier generator.
(B) DIRECT OSCILLATOR METHODS
1. A variable reactance is applied
to each of many elements making
up a "ring" oscillator.
voltages are applied to a
direct free running positive biased
multi-vibrator.
2. Audio
The ultimate would be a direct
system which used no frequencies
other than the fundamental. Thus
far, no system has been developed
which will permit direct frequency
modulation of an oscillator in the
range below 100 Kc. of sufficient deviation without distortion for the
application at hand. The desirability
of eliminating all frequencies except
the fundamental is apparent when it
is shown that many unusual things
can happen when other frequencies
are present.
Whenever the sub -carrier generator uses additional frequencies besides the desired end product, the
possibility of interference with other
equipment is immediately present.
For example, in the case of the pulse
modulation system which requires a
January. 1960
FREQ.
Ad¡.
I
SI
AUDIO
Figure 3.
UB-CARRIER
I
The positive biased multi- vibrator which produces
a
frequent» modu-
lated signal.
7
The Development and Application
of Synthetic Reverberation Systems
B
LEWIS
S.
6OODFRIEND` and JOHN H. BEAUMONT+
Reverberation is an essential element of audio program material. This article traces
the historical and engineering development of synthetic reverberation systems from
the echo chamber through acoustical and electromechanical devices to the modern
re- entrant magnetic tape reverberation generator. The use of multiple heads with
electronic re -entry and the need for nonintegral spacing of heads and extremely
uniform electronic frequency response in magnetic tape systems are analyzed.
SINCE the early days of talking pictures, audio engineers have been using synthetic reverberation to increase the apparent reverberation time of program
material. Such a technique permits broadcasts or recordings made in small absorbent studios to sound
as if they had been made in a concert hall, a cathedral, or a ca%.e. Today, reverberation is added to program material for motion pictures, radio, television.
and phonograph records.
Early systems for adding reverberation to program
signals were in general based on the use of an echo
chamber: that is. a large empty roost with highly
reflective walls. A room of 10.000 cu. ft. volume is
N..r.
Isolation
IMO
Of
Amplil
T.
.r
[way
System
Figure I. Basic form of reverberation generator.
//
capable of a reverberation time as long as ten seconds.
A microphone and loudspeaker are located in the
room. The signal to be modified is fed to the loudspeaker and is picked up by the microphone after
being modified by the room reverberation. The input
signal may be fed from a wye connection on the control console to one mixer position and to the amplifier
for the chamber loudspeaker. The microphone preamplifier signal is fed to a second mixer position. and
the amount of the reverberant signal added to the
direct channel determines the effective reverberation
time. This system is still in use today. It has one
major advantage. It is purely acoustical reverberation that is being added to the program signal. Use
of an equalizer after the reverberation channel permits the reverberant signal to be further modified to
give the bounty reverberation of a cave or the balanced reverberation of the concert hall. The major
disadvantage of an echo chamber is the amount of
space which must be allocated for a discontinuous use.
However, in a large organization, several echo
chambers may be required for use sinultaneorsly,
although for only a few minutes a day. The rest of
the time they are unproductive. Also, the problem of
getting sufficient sound isolation between several
chambers is not easy to solve. In addition, it is common to employ several microphone positions within
a chamber in order to obtain special effects. Thus, the
investment in both real estate and equipment for echo
chambers is often quite high.
Prior Art
As soon as the primary requirements for an echo
chamber signal were determined, smaller and less expensive means were considered for the purpose. The
three major requirements for synthetic reverberation
are an initial tiare delay, a series of delayed signals
similar in structure to the original signal, and a relaLewis
Figure 2.
8
E.
H. Schreiber reverberation generator.
S. (loodfriend & Associates, Montclair. New Jersey.
(Vanguard Recording Society. New York, N. Y.
Reprinted from the October, 1959, issue of the Journal of the Audio
Engineering Society.
BROADCAST ENGINEERING
STRAIGHT TALK
TO
BROADCAST ENGINEERS
NEW TRANSISTORIZED REMOTE MICROPHONE
COMBINES A ONE -CHANNEL REMOTE AMPLIFIER AND
MICROPHONE IN A HAND SIZE UNIT
By Bob
Hite
Collins Radio Company
Now, for the first time, the broadcaster
can carry a complete, lightweight remote
microphone and amplifier in the palm of
his hand. The Collins M-60 remote microphone and amplifier assures an easy mobility never before possible in remote
broadcasting.
This one -package unit can be carried in
the glove compartment of a car and you
can have on- the-spot news broadcasts without having unpleasant beeper -type interviews. By having a downtown 6 -, 10- or
12 -point loop, you can have a studio
quality interview at the news source. It is
possible and very economical to have one
loop with a number of tie point jacks at all
important news locations. In the event of
a newsworthy accident, you simply plug
into the nearest M -60 line block for a
quality, on -the-spot report. The mobility
of the M -60 at basketball games, football
games, track meets, etc., is evident because
it is quite feasible to locate several M -60
line jacks at the scene to allow the announcer the most convenient position for
the best coverage.
The small size of the Collins M -60 is
made possible only by adapting the latest
techniques used in high -fidelity transistor
amplifiers. The M -60 features an amplifier
which operates on a par with conventional
tube -type remote amplifiers. Normally, in
any tube -type amplifier, at least two tube
-
one as a rectifier and the remote microphone -amplifier eliminates the
types are used
other for amplification. In the M -60 re- usual problems associated with tubes, such
mote microphone there is only one type of as warm-up time, high power consumption,
transistor, which cuts maintenance and microphonics, ventilation and large space
requirements. These transistors require so
spare stock to a minimum.
This broadcast quality, transistorized little power that you can expect at least
amplifier assures the necessary gain to am- 100 hours of operation from the self -conplify the low level output of the micro- tained 5.4 volt mercury cell, and they
phone head, which provides the highest generate a negligible amount of heat. The
possible fidelity consistent with its size. To entire amplifier assembly takes up no more
provide ruggedness it was necessary to space than the battery. Inserting the earchoose the dynamic type of microphone phone plug turns on the amplifier and prowhich is capable of operating under ex- vides the announcer with a monitor.
The usual "rat's nest" of cables running
treme conditions without deviating in rebetween the conventional microphone and
sponse or other characteristics.
The microphone chamber is completely the remote amplifier is eliminated. This
sealed and isolated from the amplifier sec- microphone cable is replaced by an intertion so that the microphone diaphragm and nal pressure contact in the M -60. The only
voice coil operate under optimum condi- connecting cable necessary with the M -60
tions at all times. By incorporating special is the simple line extending from the base
front port features, the low frequency re- of the amplifier section to the remote line
sponse of the M -60 is extended beyond jack. Since this line is 600 ohms at high
that normally found in a dynamic micro- level, shielding is unnecessary. This means
phone of this size. The low level output of that in covering a large convention it is
the voice coil is brought through a match- possible for the first time to use unlimited
ing transformer into the first transistor amounts of line between the microphone
stage of amplification. Here the weak and the master control room.
The body of the Collins M -60 microsignal is amplified to bring it up to a plus
12 dbm line level without distortion or phone is made of aluminum and finished in
non -reflecting, blue -gray baked enamel. A
adding any unwanted coloration.
The M -60 features six plug -in type tran- modern desk stand is available for ccnvensistors which can be easily removed or re- tional desk mounting when the M -60 is
placed in seconds. By using transistors, the used in the broadcast or recording studio.
r
Collins
M
-60 Remote Microphone
COLLINS
COLLINS RADIO COMPANY
CEDAR RAPIDS. IOWA
DALLAS. TEXAS
January, 1960
BURBANK. CALIFC RNIA
9
www.americanradiohistory.com
NORMAL MODES OF ROOMS
I
1.30
J
I
30
10
I. I
I
10
20
30
200
300
.1
ROOM
DIMENSIONS
IllIIIIIIIIII
40
0
l
HIll
40
SO
I
,
60 70 6090 0d
J
1171
I
10
70
LO
609000
J
400
14'
I I
24'.36'.12'
200
1.4.1.7.1
1
loo
4O'. 4B'.
200
S00 600
FREQUENCY IN CYCLES
PER
SECOND
Figure 3. Lowest normal modes of chamber: (A) 40 X 48
X 14 ft.; (8) 24 X 36 X 12 ft.; (C) 1.4 X 1.7 X ft.
I
tively smooth decay in level. Many such systems have
been conceived. They basically are all illustrated by
the block diagram of Fig. 1. These systems may be
divided into the following general categories: three dimensional acoustical systems, one -dimensional
acoustical systems, mechanical delay systems, two dimensional mechanical delay devices, electrical wave delay lines, electro- optical systems, multiple -head
magnetic recording devices, and finally the re- entrant
magnetic tape recording system.
Some examples of these will illustrate the problems
and the progress in the field.
In 1934, a patent was issued to E. II. Schreiber on
the basic system as illustrated in Fig. 2. This is a loop
system, and if the gain of the loop is too high it will
ring just like a sound system "feeding back." A more
complex echo chamber system was covered in a patent issued to A. Pfister in 1938. In the same year,
Alfred N. Goldsmith was issued a patent for a system
using a multiplicity of reproduce heads with a magnetic wire recording system. The complexity of the
mechanical system and the inability of wire recording to provide professional recording or broadcast
quality prevented the system from becoming popular.
An ingenious application of electronics and optics
was patented by Peter C. Goldmark in 1940. It made
use of a large flat disc, the rim of which was coated
with phosphorescent materials. Recordings were made
on the coated rim with a modulated light source and
were picked off the rim by appropriately spaced
photocells.
The exponential decay of the phosphorescent material was used to approximate the acoustical decay
in a room. The mechanical and electrical complexity
of the device and its limitations with respect to noise,
frequency response, and distortion due to the phosphorescent material in addition to its high cost precluded its wide use.
In 1941, S. K. Wolf demonstrated the first use of
magnetic recording tape in a synthetic reverberation
generator.
Erase and record heads were followed by 16 playback heads. The tape was a steel ribbon. To simulate
reverberant decay the level of each signal from each
playback head had to be adjusted to match a preselected decay curve. The cost of the system and
World War II cut short experimental use of the
equipment. Following the war, plastic base iron oxide
recording tape was introduced into this country and
no further work employing steel tape was carried out
on this device.
A small box containing concave mirrors was patented in 1942 by E. W. Davis who claimed in the
patent that the mirrors would reflect sound to product "a polyphase wave pattern . . . resembling a
choral effect." Unfortunately the box is too small to
provide a sufficient delay, and any signal in it would
suffer a considerable change in quality.
The use of ultrasonic carriers modulated by the
audio signal and delayed by suitable ultrasonic delay
methods was covered in a patent issued in 1943 to
W. D. Phelps.
In 1947, a patent was issued to M. Parisier for a
system in which a small reverberation chamber could
be evacuated to control the acoustic velocity and thus
the rate of decay.
Later, in 1947, a patent was issued to Barton Kreuzer in which he disclosed a method using ultrasonic
signals modulated by an audio signal. The ultrasonic
signal was to be inaudible and to be fed by a transducer into any space suitable for reverberation
whether it was in use or not. No mention was made
of the fact that air absorption severely limits reverberation time at high frequencies. 11. F. Olson was
issued a patent on a system of transducers and long
pipes in 1950.
In addition to these systems, others -some patented and some not -were developed to produce synthetic reverberation. Among the others are the Hammond multiple, oil -damped spring system, and a
variety of magnetic tape and acoustical pipe and
transducer systems. None but the echo chamber and
the modern re- entrant magnetic recording tape system has received wide commercial acceptance.
2
0e o
2
10
It
1
11
/ÍM-.,
111
11MIM1
1/11111la111\
11111-,
WMEI_MI1TEMENS1ri
111
MIM11111=
111111N1
20
fREOuCNCr
000
1oR
Figure 4. Frequency response of a re- entrant tape system after various numbers of signal repetitions, showing
effect of inadequate uniformity of response of ordinary
tape recorder.
BROADCAST
10
www.americanradiohistory.com
ENGINEERING
Isolation
Input
Net work
Output
ar
Am ph her
Time
Decoy Rote
Control
Delay
System
Reentrant Loop
lea lapon
Amplifier
Figure 5. Re- entrant tape system. block diagram.
Acoustical Requirements
To learn why acceptance has been so limited, one
must turn to the fundamentals of acoustics. In studying the acoustics of enclosures, the equations for the
decay of sound energy in a room are used.
After a sound source has been turned off, the energy in a diffuse sound field in a roost at any instant
can be written as
E (t) = E0e 't
where b is the damping constant. The equation has a
form similar to that of the decay of direct current in
an RL circuit, having a tinte constant 1/b or 4V /:lc.
Reverberation time is defined as the time required
for the energy to drop 60 db, that is, to a value 1/10"
of the initial value; or
=
10"
bTlta db
=
6 log e 10
Tao db
=
[Eo /E
thus
(t)
I
and
I
=
(417.4c) In 10"
(24 In 10)/11301(V :t
(0.04917) /A,
where 1' = room volume in cubic feet and .4 = total
room absorption including air absorption.
Modal Structure
Now where T is to be large, the total absorption, A,
must be small and the volume must be large. In addition, to approximate acoustical reverberation, one
must approximate the room resonances, the normal
modes of decay. For a "good" live room the reverberation tinte must be long and the normal modes
must be well- spaced. 'l'he equation defining the normal modes in a room is as follows:
Also, it is necessary that the repetitions occur at
an interval after the initial sound, usually in the
range two hundredths to five hundredths of a second,
succeeding intervals being shorter.
Many systems can provide merely a prolongation
of sound energy through the repetition of signals after
discrete time intervals or at selected frequencies; however, even signals which were produced by relatively
high- quality delay devices and which prolonged the
energy with many like repetitions were rejecte-I by
the recording and broadcast industries for many
years. Also rejected were all of the earlier devices
,reviou'-1 mentioned.
Characteristics of Various Systems
Let us test several items for continuity of energy
decay and modal structure.
First let us check a large room for reverberation
time and the lowest normal nodes which will be generated.
'l'he room dimensions are 40 X 48 X 14 ft.
The lowest normal modes are shown in Fig. 8 at A.
Note the wide distribution. The reverberation time
with plaster walls is 5.2 sec. If the walls are shellacked, the reverberation tinte will be 14 sec.
A small enclosure (equivalent to a converted storage closet) such as some proposed in early patents
for direct reverberation or for models with ultrasonic
carriers. might have dimensions of 5 X 7 X 9 ft The
three lowest modes occur at 63, 81, and 113 cps which
are too high in frequency. The maximum reverberation time Nvill be 3.6 at 500 cps with all surfaces shellacked plaster on concrete or brick. However, with
air absorption at 16 kc, the reverberation time would
be only 0.7 sec. for such an ultrasonic signal. Also, the
first reflection will occur in less than 0.01 sec. This is
why a small echo chamber sounds so poor.
Pipes
Four pipes of 25, 55, 75, and 110 ft. in length will
produce an initial delay of 22.2 inset. and a maximum
delay of 97.5 inset. and correspond to the lowest
modes of a roost of 37.5 X 27.5 X 12.5 ft. AItF ough
0
o
o
o
o
1r,y
t
2
(r)
+(\
\ I/
+
o
o
o
/s
o
o
o
0
Toes
Itwael"T
trinco
0
0
0
o
r44KtiC
0
0
0
0
0
With two pairs of opposite walls completely absorbent, the equation reduces to fr,s,t = (e;'2) WI).
It is the correct modal structure that provides
smooth decay and thus realism and acceptability in
synthetic reverberation.
0
0
0
0
0
0
o
o
0
o
o
.4Ap11
e
Figure 6. Effect of nonintegral head spacing in filling
time intervals.
January. 1960
I I
www.americanradiohistory.com
Figure 7. Reverberation generator using a tape loop and
seven playback heads.
the normal modes arc suitable such an arrangement
floes not meet the requirements for prolongation of
energy since the energy is distributed in four packets
and the effect is obviously not exponential but may
-
be defined as
aEt + bE2 + cE:S
E (t)
where a., b, and c are less than unity and E's are the
sound energy values at the earlier time when the
source is shut off.
If the number of pipes is increased sufficiently, the
system becomes quite effective, but initial and maintenance costs are prohibitive. Also, in general the
delays most be of fixed duration.
Springs and Plates
hxamining a spring system, we find that the transmission velocity of usual metals is 10 to 15 times
greater than that for air. "Thus, to achieve an appropriate initial time delay requires excessive lengths of
materials. Common spring systems and metal plate
or screen systems require that the signal he reflected
many more times per second than occurs in a large
chamber. For example, a metal plate eight feet by
three feet is equivalent to an air cavity approximately
two inches by six inches. 'Thus, the signal has considerably more opportunity to be modified in frequency spectrum on each reflection. It should be
noted that a spring provides true exponential decay
but that the damping varies with frequency. This
gives springs and other metallic reverberation systems
a typical ringing or "metallic" characteristic.
Plate and wire screen systems are also afflicted with
the sane problems as springs-long decay at the expense of quality degradation and one -dimensional
modal characteristic.
Some attempts have been mule recently to use
light metal sheets excited in their plate mode rather
than their longitudinal mles. In such systems the
result is highly frequency dependent and such sys-
tenis tend to have a hooray quality at low frequencies
for long reverberation times. They are also limited in
maximum decay time to two or three seconds at all
except extremely low frequencies because of the size
limitation. Also, they do not provide the initial delay
in the arrival of the first reflection, essential to naturalness.
To achieve realistic synthetic reverberation, one
must provide characteristics similar to those in a.
large reverberant space which were discussed earlier:
(1) A discrete time delay for the first few reflections
similar to the delay achieved in a chamber (Fig. 13) ;
(2) exponential energy decay; and (3) nonresonaut
decay similar to a chamber with widely spaced normal modes.
The Re- Entrant Tape System
After World War II, it occurred to many people
that modern magnetic recording tape would provide
an excellent storage medium, and the time delay between recording head and playback head would provide a suitable delay for the first reflection. Attempts
to use commercial tape recorders for this purpose, returning a portion of the output to the input, have
not been successful. The reasons are basic. First, only
one time delay is provided corresponding to a one dimensional room, a pipe. Second, the use of the electronic equipment of a commercial tape recorder for
such a re- entrant system introduces amplitude -frequency changes which, in turn, cause an unnatural
ringing sound in the output, as in Fig. 9.
Thus, a new criterion must be added to that of
the three earlier ones. The re- entrant system must be
sufficiently uniform in response to produce hundreds
of generations of copies front the original signal with-
out quality degradation.
Considering a re- entrant system, such as that
shown in Fig. 10, one can see in Fig. 4 that losses of
0.1 db at 100 and 7000 cps will become 10 db after
100 generations. Losses of 0.5 db at 40 and 12,00(1
cps will become 50 db after 100 generations. This is
the basic problem of a re- entrant system. However,
a re- entrant system with two carefully equalized play-
0
0
0
0 0 0
o
0
o
00
o
0
00
0
00
CO
0
0
00
00
-20
LARGE ROOM
(A0'. no'.
id)
-30
0
0.
02
SECONDS
Figure 8. Reflections in an echo chamber 40
80
os
0
X
110
X
ft.
BROADCAST ENGINEERING
I2
www.americanradiohistory.com
on
SECONDS
Figure 9. Operation of
a
steel coil spring.
back heads and suitable delays between heads should
provide long smooth decays. Since the output level
of such a system is an exponential function of time,
the system meets this criterion.
The spacing of heads and the tape speed determine
the time delays and effective normal modes. The tape
speed is set at 30 ips by the demand for extremely
uniform response in the range 100 to 10,000 cps, with
only simple RC equalization permissible. With more
complex network equalizers, it is impossible to maintain a sufficiently flat frequency response. With still
higher tape speeds than 30 ips, tape and head life
are greatly reduced.
We have thus determined the various criteria for
a re- entrant magnetic tape recording synthetic reverberation generator. No difficulty is found in achieving such a system in practice. The basic design parameters are tape speed, frequency response, time
delays, and number and spacing of playback heads.
Having fixed the tape speed at 30 ips, the spacing
of heads was arranged to achieve a minimum initial
time delay Of 28 msec. Time delay for the second head
was set at 63 msec in the prototype model which
gave a delay in time between the first and second
heads of 35 inset.
If a portion of the playback signals is returned to
the input the nonintegral relationship between the
head spacing delays provides new signals between the
signals provided by the pickup heads on playing the
second generation recording (Fig. 0).
Considerable experimental work has verified the
design criteria. Translating these requirements into
electronic and structural ternis, we can state: (1) The
tape and electronic system must be flat to within
± 0.1 db from 100 to 10,000 cps. (2) The tape speed
shall be 30 ips. (3) The minimum record -to- playback
head spacing shall be 20 msec. (4) The maximum
spacing between successive playback heads shall be
50 msec. (5) The ratio of spacings of the heads shall
not be integral. (6) A re- entrant record -playback system is required. (7) At least two playback heads
must be used (but as many as six are permissible)
To discuss the problem of head spacing a bit further, it should be pointed out that the use of playback heads spaced by an integral ratio front !h record head merely adds level to the signal but contributes no effective reverberation. The use of non integral spacing provides additional energy in the
time domain at such points as to contribute to the
reverberant energy but not adding appreciably to the
voltage amplitude of the signal; i.e., the decay curve
is smoother.
Figure 7 shows a current version of a magnetic
tape synthetic reverberation unity designed in accordance with these principles.
It is equipped with seven playback heads, some of
which are positioned for echo effects. 'l'heir use is
controlled by the toggle switches located over the
central head assembly. The VU meter is usd to
verify input signal levels and adjust output levels to
correspond to levels in the user's system. Controls
are also provided to adjust the level of the reverberant signal in relation to the direct signal, and to
control the rate of decay. The rate of decay control
in effect controls the damping constant in the exponential equation
E (t) = E e -1,t
and so changes the effective reverberation titne
Side -by -side comparisons between an echo chamber (Fig. 8) and this re- entrant magnetic tape reverberation generator (Fig. 6) show that it can duplicate all of the useful effects of the chamber. Some
chambers can sustain single tones from oscillators for
extreme periods of time. Although careful adjustment
of the tape generator can duplicate this effect _t has
no practical use, and no attempt is made to u_djust
production machines for this purpose. It is impossible to tell the difference between music and speech
signals to which reverberation has been added -y the
synthetic reverberation generator and those from an
echo chamber.
For comparison we show results from a steel spring
(Fig. 9) and from a multiple pickup tape system
without feedback (Fig. 10).
1
s
u.
S.
Patent 2,748,192.
.
Figure 10. Operation of a non -re- entrant tape loop system using ten playback heads.
January, 1960
13
www.americanradiohistory.com
THE EFFECTS OF TRANSMITTER SOUND POWER
REDUCTION ON TV RECEIVER PERFORMANCE
report of the Television Allocations Study Organization indicates that
receiver performance would be adversely affected by TV sound power reduction.
The
TESTS were made on representative television receivers to determine
the effects of a reduction in sound
power on the performance of television receivers. The receivers used
in these tests included the various
types of sound detector circuits currently in use and the results obtained are therefore felt to be representative of those which can be
expected in the field using new,
aligned receivers of modern design,
properly installed.
The following types of tests were
made in order to determine the extent to which receiver performance
was affected or modified by a reduction in transmitter sound power
below the value currently standardized, i.e., between 50 per cent and
70 per cent of the peak visual
power:
1.
2.
Thermal noise (signal -to -noise ratio)
Impulse noise rejection
Additionally, consideration was
given to the problem with respect
to:
1.
2.
3.
4.
5.
6.
Loss of service area
Adjacent -channel interference
Fine -tuning characteristics
Fading
Co- channel interference
Sound vs. picture performance
It has been the experience of receiver manufacturers silice receivers
were first put on the market that
there has been an ever present demand for greater sensitivity. Users
in fringe areas are in many cases
willing to install receivers at considerable expense provided a good, re-
liable sound signal can be obtained
even though the picture performance may be subject to fading, interference, impulse or thermal noise
of a magnitude such as to cause serious picture degradation, or even a
loss of picture from time to time. In
such areas a reduction in sound
power would result in serious impairment of service and in many
cases a complete loss of service.
With respect to thermal noise, the
Committee 2.6 report, Figure 2,
shows a loss as high as 2 db in
signal -to -noise ratio for each db of
sound carrier power reduction in low
signal areas.
There are many areas where the
impulse noise is considerably above
the thermal noise level. Receivers
operated in these areas would suffer
a loss of tolerance to impulse noise
of about one db for every db reduction in sound power. This performance loss occurs at strong signal
levels as well as at weak signal
levels. This is shown in Figures 3
and 4 of the committee report.
Figures 5 and 6 of the committee
report show the loss of service area
for the low and the high VHF
bands, considering only receiver
noise. This amounts to about 20 per
cent on low -hand channels and 10
per cent on high -band channels for
a 7 db reduction in sound power.
The effects of sound power reduction on the receiver performance
characteristics studied by the committee were, in every case, adverse,
except for adjacent- channel interference in a small percentage of the
receivers where the resulting improvement might be short -lived for
reasons mentioned in the committee
report.
It is the consensus of the Panel
that any reduction in sound power
would be detrimental to a significant number of users of television
receivers for the reasons mentioned
in the report.
The question which is of concern
to TASO Panel 2 and to Committee
2.6 is the extent to which receiver
performance characteristics will determine the change in television
transmitter service area in the event
of a change in sound -to-picture
power ratio.
All modern television receivers use
an essentially similar system of reception of sound signals and since
an understanding of the system is
necessary in any study of the material of this report a short description will be given.
Both visual and aural signals
picked up by the antenna system
are amplified and converted to an
intermediate frequency in typical
superheterodyne practice with no intentional amplitude selectivity between the two carriers. Both signals
are then amplified by a wide bandwidth intermediate frequency amBROADCAST ENGINEERING
14
www.americanradiohistory.com
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Ex
plifier system, the output of which
is coupled to a second detector. The
output of the second detector includes, in addition to the demodulated visual signal, the beat product
of the visual and aural carriers,
which is a 4.5 me signal carrying the
frequency modulation information of
the sound carrier. This 4.5 me signal is then amplified further and
fed to a frequency modulation detector, which may he of several different types depending on design
engineer preference. These types
vary in method of operation and
circuit detail but within normal
variations are substantially similar
in performance. In the combined
picture and sound intermediate frequency amplifier, the sound signal
is attenuated only enough to minimize the appearance of the amplitude modulation of the picture signal from appearing in the 4.5 me
beat signal output of the second detector and to prevent the loss in picture quality, such as contrast ratio
and beat patterns. Further, it is usually necessary to provide additional
attenuation at 4.5 me in the video
amplifier circuits to reduce the visibility of the beat pattern in the picture output. It is necessary to provide this attenuation after the sec-
and detector, rather than in the intermediate frequency amplifier in
order that the maximum sound signal for maximum sound sensitivity
can be obtained from the output of
the second detector. The major advantage of this method of sound reception, known as an "intercarrier"
system, is that it is generally free
from dependence on the local oscillator frequency setting. The frequency of the signal detector is dependent only on the frequency spacing of the transmitted visual and
aural signals. This means that the
television receiver viewer need not
accurately set the local oscillator for
good sound reception but may tune
for optimum picture reception. Also,
The sound system is not susceptible
to serious performance degradation
ill the case of local oscillator drift or
local oscillator frequency modulation such as may occur because of
receiver hum. (It should be noted
that without the use of intercarrier
sound reception methods, dependence on local oscillator tuning and
performance would have made the
problems of UHF receiver tuner design almost intolerable.)
The present standards of television transmission provide that the
aural transmission power shall be
January, 1960
l::.w.:
between 50 per cent and 70 per cent
of the peak visual transmitter rower.
The effects of a reduction in -.ransmitted aural power, from these
standards, on typical modern television receivers will now be considered.
1.
Thermal Noise Performaì.ce
-
A reduction in transmitted aural
power will result in poorer re eiver
thermal noise sound performance
which will, by reduction of re.eiver
fringe area sound performance, reduce the sound coverage of aay given
transmitter. To obtain experimental
verification of the reduction of ,ound
channel thermal noise performance,
measurements were made on nine
different receivers in the engin. ering
laboratories of some of the me.nbers
of TASO Panel 2. Four dif ;erent
types of 1"Al detector systen s are
represented in these receivers covering every type in use today. In all
cases, measurements are for ene of
the lower VHF channels. Figure 1
represents the data of one of these
receivers which is typical of the
group. Sound channel signal -to-noise
ratio is plotted as a function cf picture -to -sound ratio for a number of
picture carrier signal levels. t can
be seen that for each signal level
there is a threshold value of pi:ture1
15
www.americanradiohistory.com
to -sound ratio below which the signal -to -noise ratio degrades rapidly.
Figure 2 presents a summary of these
data for all the measured receivers.
The loss of sound channel signal -to-
noise ratio per unit reduction in
sound carrier is plotted as a function
of picture carrier level. In these data
the average of all the receivers is presented and the data for the measured extremes are also plotted. As
an example, from this curve it can
be seen that with 20 microvolts of
picture signal (open circuit antenna
voltage delivered through a :300 olun
dummy antenna to the receiver) , an
average loss of about 1.5 db in signalto-noise ratio will occur for each db
of aural carrier power reduction.
These data are for new, aligned receivers of modern design. If we add
the losses expected due to misalignment, tube aging and antenna orientation and mismatch, as well as
transmission line losses, it is reasonable to expect that this type of signal-to- noise ratio loss would occur
in the 100 to 200 microvolts -permeter range of signal strength in a
substantial number of receivers currently in the hands of the public.
-3
-5
-7
-9
Sound quieting sensitivity which
takes into acount only thermal noise
considerations is 30 microvolts for
the typical receiver in the group used
to obtain these data. In the report
on receivers prepared by Committee
2.1 of Panel 2, the Picture Sensitivity
for 78 receivers reported varied from
4 to 150 microvolts. The distribution
of sensitivity shows:
12.8%
34.6%
19.2%
11.5%
9.1%
12.8%
Less than
10 microvolts
Between 10 and 20 microvolts
Between 20 and 30 microvolts
Between 30 and 50 microvolts
Between 50 and 100 microvolts
Greater than 100 microvolts
The importance of fringe area performance may be judged by the fact
that more than 66 per cent of the
receivers reported picture sensitivities better than 30 microvolts.
2. /in pulse :Noise Rejection Per forniance
common form of noise
interference in the sound channel is
that caused by automotive ignition
noise, electric motor commutator
noise (shavers, mixers, vacuum cleaners, etc.), arcing switches, and lighting. This form of noise is usually
lumped under the general heading of
impulse noise. In order to measure
the effect of aural carrier power re-
-A
duction on receiver performance ill
the presence of this forni of noise, an
interference source, such as a non synchronous 60 cps rotating arc device was coupled through a variable
attenuator into the antenna circuit
of the test receiver in parallel with
the desired standard visual and aural
television signal. The interference
noise signal input to the receiver was
increased until its presence was noted
in the sound output of the receiver
either by aural or measured output
detection. The aural signal was then
reduced in steps and at each step the
change in noise interference required
to restore the original condition was
recorded. Data were obtained on
seven different commercial receivers,
independently measured in the laboratories of Panel 2 members, and
data for a typical receiver are plotted
in Figure 3 for visual signal input
levels ranging from 50 to 10,000
microvolts. Figure 4 presents a plot
of data for the relative impulse noise
level for constant audible interference as a function of sound- picture
ratio. This is the average of all data
for all seven receivers measured. A
loss of tolerance to impulse noise of
-II
RATIO OF SOURD- 7O- PICIVRE CARRIER LEVEL IR db
BROADCAST ENGINEERING
16
www.americanradiohistory.com
about 1 db for every db of reduction
in aural power is noted. This performance loss occurs at strong signals as well as weak; the performance
loss with reduction of aural power is
as great at 10,000 microvolts as it is
at 50 microvolts. As in the previous
case for thermal noise, these data are
report of Committee 2.1 of Pa el 2
shows that receiver attenuation; for
the lower Adjacent Channel S Sund
Signal vary widely, ranging fro n 14
db to 60 db, distributed as follows:
each db drop in sound
power. This was obtained from the
average degradation in signal -tonoise ratio at the 30 db level in data
furnished by the members of this
.57 (II) for
Committee.
Finally, the reception range and
loss of service area was determined
from the FCC curves of expected
field strength, F(50, 50) assuming
maximum authorized power in the
TV transmitter, and representative
antenna heights.
'l'he attached Figures 5 and 6 show
the loss of service area for VHF
channels 2-6 and 7 -13 resulting from
a reduction of sound power below the
present minimum of 3 db below the
peak video power. The service area
is reduced about 20 per cent on the
low VHF channels and about 10 per
cent on the high VHF channels if a
7 db reduction in sound power is
na(Ie.
4. Adjacent Channel Interference
-A reduction ill transmitted aural
power would reduce the lower adjacent channel sound interference in
those areas where it now exists by an
amount equal to the sound power reduction. Examination of the receiver
for new, aligned receivers of modern
design.
3. Loss of Service Area
order
to show the loss of service area resulting from a reduction of sound
power, the required field strength in
db above 1 uv /meter to produce 30
db quieting was determined by measurement of the quieting sensitivity
for representative TV receivers under
existing transmission standards and
calculation of the equivalent field
strength using the formula and data
presented in TASO Committee 2.4's
report. The average figures for antenna gain and transmission line
losses were used for channels 4 and
10 which are about in the middle of
the two frequency ranges. The required increase in video and sound
signal levels to compensate for a reduction in sound power with respect
to video power was determined to be
-L
Less than 30 db
Between 30 and 40 db
Between 40 and 50 db
Greater than 50 db
11.8%
42.1%
13.1%
32.9%
Other factors which are of in poibut less susceptible to a cuautitative analysis include:
5. Fine Tuning -A reduction in
transmitted sound power will insult
in a more critical requirement for
"fine tuning" in weak signal t.reas,
thus increasing the need for skill and
,judgement in adjusting the fine tuning control, a. function in which nost
consumers are presently inept.
6. Failing -A reduction in transmitted sound power will aggravate
the effects of fading, either natural
or manmade, such as airplane flutter,
on t.lie sound performance of the TV
rcceivcr.
In
7. Co- Channel Interference
some locations, at present. botlL picture and sound reception is limited
by co- channel interference. Co -ShanncI picture interference can be con tailed,
-
(Continued on page 38)
1.00
90
YNO
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NN.YY
80
Y000Nip°ói
YN
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70
N
Y
Y.Y
Low VHF Channels 2 -6, Trenemltter Power - 100 Kv
Loss of Reception Range and Service Area
from a Reduction of Sound Power
Er 28 db
0 3.9 db
Ed 2.9 db
L -1 db
22.2 db
F
Laboratory Data (Video Signal for 30
Comm. 2.4 Report, Overall Avg. Cb. 4
Comm. 2.4 Report, Overall Avg. Cb. 4
Comm. 2.4 Report, Average of vet and
Comm. 2.4 Report
FCC Curves F(50,50)
50% of location.,
High VHF Channels 7 -13, Transmitter Power - 316 Kv
Iosa of Reception Range and Seance Aree
from s Reduction of Sound Power
db Quieting)
Antennas
Er 30 db
Mtenose
en..
dry Lines
7.4 dD
Kd 6.1 db
L -2 db
O
F 30.7 db
50% of the time
Laboratory Data (Video Signal for 30 db Quieting)
Comm. 2.4 Report, Overall Avg. Ch. 10 Antennas
Comm. 2.4 Report, Overall Avg. Cb. LO Antennas
Comm. 2.4 Report, Average of vet and dry lines
Comm. 2.4 Report
FCC Curves F(50,50) 50% of location., 50% of the time
FL
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J;an_a:y, 1960
7
17
www.americanradiohistory.com
STEREOPHONIC BROADCAST
EXPERIMENTS AT KISW -FM
The system described in the August issue of Broadcast
Engineering has now been tested on the air. Results of these tests
and experiments are described in this article.
By
ON Nov. 6, 7 and 8, during the
third annual Hi Fi Music Show
(Rigo Enterprises) held in Seattle,
Wash., KISW -FM broadcast six
hours daily of stereophonic programs
using a method announced several
months ago and published in August,
1959 (Broadcast Engineering).
The method as outlined had proven
sound and workable on paper and
some experiments had been conducted but an actual broadcast using
this method had not been tried.
Equipment was built for one transmitting unit and one receiving unit.
Several problems encountered had
not been reckoned with until construction was under way. Due to the
lack of time, 19 days in all, engineering had to go by the board and
any workable method that would accomplish the desired results was followed for expediency. The results
were far greater than anticipated but
ELLWOOD W. LIPPINCOTT*
much was to be desired in the way
At the transmitting end the right
of simplification.
and left input channels were fed to
The transmitting unit consisted of the grids of the input amplifier (12a five -tube amplifier and switching AX7) . The cathodes were switched
circuit. In addition three tubes were by a driver tube (12AÚ7) and the
utilized in the synchronizing circuit output of both halves of the driver
which would assure that both the were connected in parallel and fed
transmitting and receiving ends to a cathode follower (6C4) output
would operate in exact unison or amplifier. The combined signals
from both right and left channels
synchronization.
A switching frequency of 30,000 were then fed to the KISW -FM
cycles was chosen for the simplicity audio console and broadcast as a
and ease in adjusting with the composite signal. A 30 Kc multi equipment at hand.
vibrator (12AÚ7) generated the
It should be pointed out that the switching pulses and operated the
frequency of 30 Kc is too low for switches through a driver (12AÚ7)
switching because, for instance, a 50This same 30 Kc pulse was amplicycle tone is sampled 600 times per fied then fed to a 15 Kc multivibracycle while a 15,000 -cycle tone is tor, again amplified and fed to the
only sampled twice per cycle causing telephone line for synchronizing pura reduction or attenuation of the
poses.
higher frequencies. Some compensaIt should be added here that time
tion could be accomplished by pre - would not allow for building the necemphasis.
essary synchronizing equipment for
.
*IUSW -FM,
9201
Roosevelt Way, Seattle 15, Wash.
BROADCAST ENGINEERING
18
www.americanradiohistory.com
Figure
1
Method of Compatable
Stereophonic Broadcasting
for FM Stations.
A
Trans.
9C
Ml;d
Electronic Sw.
Right
Sync.
Gen.
Left
broadcasting the pulses over the air
so a 15,000 -cycle line was ordered
from the local telephone company
and i sed for synchronizing only.
Both tereo channels were actually
broad ast and received over the air.
At he receiving end, to eliminate
transients and other "garbage" that
appeared on an oscilloscope, several
extra tubes were added until the
final unit used in the demonstration
contai ed six tubes in the amplifying
and s itching unit and one tube and
two di des in the synchronizing unit.
The discriminator output of a
Scott F\I tuner was fed to the two
grids of the input amplifier (12AX7)
corn ected in parallel. The outputs
of the ,c amplifiers feci two separate
switchcr units (12AU7s) and two
driver units (12AU7s) controlled by
a single inultivibrator (12AU7) generating the 30 Kc switching pulses.
Synchronizing of the receiving gen-
.
Sync.
Electronic Sw.
Sep.
Amp.
Amp.
Right
Left
orator with that of the transmitter
was accomplished by taking the 15
Kc tone from the telephone line and
feeding into a pair of diodes connected with their inputs in push -pull
and their outputs in parallel thus
acting as a multiplier and supplying
a 30 Kc pulse. This pulse was amplified through two stages (12AÚ7)
and fed to the grid of the receiving
multivibrator thus controlling the
entire system from the 30 Kc pulses
generated at the transmitting end.
The two switcher outputs were
fed to two separate power amplifiers
and then to their respective speakers.
All equipment was completed and
ready for bench testing just six days
prior to the first scheduled broadcast. Bench testing required some
minor changes but as a whole the results were very encouraging.
One day prior to the first broadcast the installation was completed
January, 1960
at the KISW -FM transmitte- and
the Hi Fi Music Show some eight
miles distant.
At Q p.m., Friday, Nov. 6, 1959,
KISW -FM broadcast the first of six
three -hour programs in compatable
stereo using the system outlined. All
six programs were received is stereo
with no discernible loss of fidelity or
signal -to -noise ratio and with no noticeable cross talk between channels.
Public acceptance and enthusiasm
at the Hi Fi Music Show was beyond
expectation while home listeners reported they could detect no difference between the stereo and monaural programs.
Now that the method of con--patable stereophonic broadcasting for
FM stations has been reduced to
practice, further experiments will be
conducted to simplify the equipment
and to increase the switching frequency to about 100 Kc.
19
www.americanradiohistory.com
THE ROLE OF TAPE IN RADIO'S RISE
Magnetic Tape
has been an
important factor
to contribute to radio's progress
in
in
radio's growth and will continue
the future with the growth of
stereophonic broadcasting and other new techniques.
REMEMBER those predictions about
radio? IIow it would lie down and
fold its hands helplessly before the
on- rushing tide of television?
Well, it didn't happen, did it?
On the contrary, radio broadcasters are doing quite well for themselves these days. Quite well. indeed.
There are more stations on the air
than ever before. And these stations
are broadcasting for more hours a
day than ever before. 'l'he nation has
more clear channel stations; it seems
that everyone is increasing his transmitter power.
Radio, as they say, goes every where. Its audience is everywhere
in every room of the home, in the
automobile, at the hall game, on the
beach. With the advent of more good
music programs, including stereophonic presentations, entire new listening groups are being opened up
to the radio broadcaster. lìa Iio's
audience. instead of decreasing, has
mounted steadily. As a communication medium, radio now enjoys unprecedented importance.
Along with this surging to new importance, however, has developed a
serious shortage of qualified personnel to staff the increasing number of
stations and their expansion of programming days.
How are stations taking up the
slack?
The answer is in tape.
When a station needs five qualified people and has only three, it depends on its professional tape record-
ing equipment to "spread the staff,"
provide a variety of voices, record
programs on weekdays and play
them back nights or weekends, keep
the station ou the air more hours per
week without going to overtime for
Don Roberts, KOA (Denver) personality, starts one of the station's recorders.
As part of its continuous recorder operation, the station has two recorders in
the announcer's booth. While one is on playback, the other is loaded and cued.
This provides split-second program timing.
-
20
www.americanradiohistory.com
professional broadcast tape re( girder
can meet such operational (len ands.
Why is this true? Dependability
of the equipment is essential. AZany
of the stations operate without having a second recorder for backup.
Furthermore, the simplicity of the
operation of the professional tape recorder is important. In today's radio
station, the recorder is operated by
several different individuals, often
non -technical in their training. The
professional tape recorder is ersy to
load and once loaded, it's a case of
simple push -button operation.
Ruggedness also is a factor. Stations often use the recorder in a combination of studio and rough field
)plications.'l'he recorder tntist withstand adverse climatic conditions,
heat, humidity, dampness, ele.
Not to be overlooked, of cou:se, is
the matter of economy. Years of experience have proved that the fully
professional recorder costs fa- less
per hour of operation. This r_.sults
from reduced maintenance, longer
practical life, more accurate program
timing and far higher reliabilit;..
WFAA (Dallas) told Ampex that
its 24 professional recorders da not
average an hour of maintenance time
per machine per month.
When asked how many hours a
month the professional machines at
WKRC are down for maintet ance,
Dore Frantz, chief engineer at the
Cincinnati station, replied: "Practically none."
\\J PR reported its mainte Lance
of Ampex machines consists of cleaning the heads, checking the tubes
and oiling the motors on a routine
basis.
KOTA's Elmer Nelson sai his
staff has no maintenance worries
with the professional recorders "We
watch the lubrication carefully and
clean the heads about once a week.
We find if they're checked on at
least once a month, we haN e no
trouble."
With widespread installation of
fully professional equipment will
come complete realization of tte potentials for radio programming with
tape.
There is great promise of commercial program production on a syndicated basis to supplement or substitute for network program service beI
James F. Zimmerle (left), KOA engineer, patches in the network while Jay F.
Graves, radio engineering supervisor, threads up one of the recorders which
provide continuous service in recording and playing back the net.
the staff, make it convenient for outside participants to appear on pro-
grams, provide remote broadcasts at
little expense, sell more time by offering sponsors any announcer at
any time, build station audience by
adding variety and interest, cut
costly errors by checking copy at
time of reading.
According to a survey conducted
recently by Ampex Corp., stations
are using their professional tape recorders as much as 50 hours a week
for local program delay, plus as
many as 1 .20 spots a week.
A station in Illinois reported it
keeps ik professional recorders in
operation continuously from (i a.m.
to 6:30 p.m. every clay. And W IS
(Columbia, S. C.) runs its professional recorders 12 hours a day.
The five Ampex recorders at
«'KRC (Cincinnati) provide a continuous F\I music system from 10
a.m. to midnight daily. The
automated equipment also throws in
voice announcements. The professional recorders at KTTN (Trenton,
\Io.) run 13 hours a day.
Percy Kuhn, chief engineer for
WJPR (Greenville, Miss.), said he
uses his professional tape recorders
all day long. "The only time we
don't use them is when we go on net-
work, which is very seldom," he said.
"'They run on the average of about
15 hours a day."
Elmer Nelson is chief engineer at
KOTA (Rapid City, N. D.) where
seven Ampex units are in operation.
"A lot of our network stuff is delayed,," he reported. "So we have the
recorders in almost constant use.
from 6 a.in. until fairly late at night."
(Portland, Ore.) uses one
of its Ampex machines for delaying
the network (ABC) one hour during
the daylight saving period. By arrangement of a looping mechanism.
it runs 24 hours a day.
"Wee record the net on it and then,
an hour later, we play it off,'' chief
recording engineer Bill Rohrer reported. "We have the recorder arranged to erase the tape after it has
played back its content and it records the new net right away." With
a one -hour loop arrangement, Ii \\'JJ
can do this continuously for an indefinite period. The recorder rubs
l4 hours a day.
As a part of its survey. .Anil x
sought information on how its professional tape recorders were holding
up under such continuous heavy use.
The station engineers were unanimous in their opinion that only the
January, 1960
1
(Continued on page 36)
21
www.americanradiohistory.com
Automatic Payola Detector
By
PROFESSOR OSCAR VON DER SNIKRAH
NEW UNIT SOLVES BASIC INDUSTRY PROBLEM
IN THE EARLY DAYS of broadcasting
it was considered normal operating
procedure in the majority of sta-
tions for the transmitter engineer to
"keep the log."
Throughout his shift, the engineer
logged each commercial or reference
to a commercial product at the time
he heard it. The accounting department would then double check the
log kept by the engineer against the
original program log used at the
studio.
Although this practice kept the
program department always at odds
with the engineering staff, it did
prevent any of the practices now
known as "payola."
As the complexities of the communication art of broadcasting grew
with the coming of television, remote control and automatic station
operation, these watchdog procedures fell by the wayside much to
the chagrin of the entire industry.
Foreseeing the side effects now
arising that have brought widespread investigations and severe
shakeups, our secret laboratory has
been working feverishly for several
years to perfect the electronic payola detector.
Although we failed miserably to
deliver the unit in time to prevent
the government inquiry, we can report our developments at this time
to safeguard the industry against
future invasion.
The first experiments were patterned after the famous "lie detector" unit that electronically detected when a person was telling a lie.
By attaching electrodes to various
parts of the body, minute electric
currents could be recorded that accurately revealed reactions of the
human nervous system when the Such phrases as "be sure to buy" or
subject had told a lie.
"see it now-" or "it costs only
will
By application of inverse feedback cause the meter to register commerprinciples to this method, some of cial content in accumulative fashion.
the output voltage was fed back to In other words, the meter needle will
the brain in order to give larger un- move up a division for each commerdistorted indications on the wave re- cial phrase, with a capacity of 100
corder. As much as 12 db. feedback units for full scale. Each half-hour
was used at times to clean up the the meter will be read and logged
waveform.
after which a reset button returns it
It wasn't practical, however, as it to zero for the next period.
Any one of 20 different phrases
was found no one would permit the
attachment of electrodes to the an- will cause a unit to be registered.
nouncers and entertainers, especially Exact wording of the phrases will be
on TV. This and the fact that we kept secret so that announcers canalmost lost a volunteer announcer not defeat the purpose of the unit
from electrocution by the attached by coining new phrases.
electrodes, led us to abandon this
The logged units for each half hour are then correlated to the proarea of research.
Since another well known group gram log for each day and any diswas already perfecting a device that crepancy will immediately appear.
translated audio directly into a
At this time we are working with
typewriter, we decided to collabo- one of the larger computer manufacrate with them and use some of turers to develop one of their matheir principles. In our case, we did chines to use for this application.
not want to convert all of the audio
When perfected. this system will
into typewritten material but only require only three additional persons
use "selected" audio to operate an on the staff of each station and will
indicating meter that could easily he forever take the pressure off of staread by inexperienced non- technical tions. Although arriving on the scene
personnel.
ten years too late for the prevention
Through the use of special filters, of the "payola" scandals, its future
the device selects well known phrases use at each station will prevent a
commonly used in radio commercials. repetition of the recent investigation.
-"
Figure I. The Payola Monitor samples
R. F. at the input to the antenna and
can be remotely controlled and read
if necessary. A plug in R. F. section
allows it to be used in conjunction with
either A. M. or F. M. transmitters. A
TV model will soon be developed.
BROADCAST ENGINEERING
22
www.americanradiohistory.com
GOING TO A KILOWATT?
You can't do BETTER than
a
BAUER
CHECK THESE FEATURES WHEN
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V
MODERN TETRODE CIRCUITRY
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V
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V
VACUUM CRYSTALS
DIFFERENTIAL PLATE TIMER
NINE METERS, NO " MULTIMETER"
REMOTE ANTENNA METER POSITION
RECESSED
CONTROL PANELS
EXCEPTIONAL TUBE LIFE
FB-1000-J
RELIABLE UNATTENDED OPERATION
COMPLETE ACCESSABILITY
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that gives you everything
but trouble"
1/
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LOWEST INITIAL COST, LOWEST OPERATING
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Write for descriptive brochure to:
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P. O. BOX
1101, SAN MATEO, CALIFORNIA
Quality Custom Transmitters Since 1926
OTHER PRODUCTS:
MEMBER WCEMA
AM TRANSMITTERS, 5 and 10 Kilowatt
HIGH LEVEL AUDIO MODULATORS.
January, 1960
23
www.americanradiohistory.com
AMENDMENTS AND PROPOSED CHANGES
OF F.C.C. REGULATIONS
OPERATION OF LOW POWER TELEVISION BROADCAST REPEATER STATIONS
Notice of Further Proposed Rule
Making
1. In its Report and Order (FCC 581d3á) issued in this proceeding Dec. 30.
10.58, the Commission reaffirmed its concern with the problem of inadequate television reception in small, remote connuu-
nities but concluded that the limited
number of channels available in the VHF
television band and the hazard of harmful interference to the reception of television broadcast stations as well as other
radio services on adjacent frequencies,
made it desirable to limit TV repeater
stations to the ITHF hand.
Reconsideration of its decision of
Dec. 30, 1958, was requested in pleadings
filed on Jan. Z6, 1959, by Western Slope
Broadcasting Co.. Inc., kiln on Feb. 4,
1959, by the licensees of 16 television stations in California, Colorado. Idaho,
Montana, South Dakota, 'l'exas, Utah
and Wyoming. In the interim the ('ommission lias engaged in a continuing restudy of the problems associated with
the licensing of low power repeater stations in the VHF band and has endeavored to re- evaluate those problems in the
light of the foreseeable advantages and
disadvantages which would flow front
the authorization of VHF repeater operations under a number of alternative sets
of technical and operating conditions.
The more restricted and rigid such requirements are drawn, the greater protection they would afford against the interference and other undesirable results
risked by the authorization of repeaters
in the VHF band. On the other Maud,
the more technical and operating requirements are relaxed the lower the costs of
construction and installation of such
equipment. The Commission has emleayored to seek an optimum balance between extremes and believes that the requirements set out in the appended draft
rules, all timings considered, reflect such
a balance. We have accordingly decided
to invite the comments of interested parties on tle proposals appended her, to.
The draft rules would parallel, insofar as
appropriate, the present rules covering
television broadcast translator stations
using authorized UHF channels.
3. One of the more difficult problems
which must be met if these devices were
to be permitted in the VHF television
broadcast band is that of interference to
television broadcast reception, interference to other radio services which occupy
bands interspersed through the television
.
I
bards, and interference between translators. The first of these is usually stet
by limiting the maximum power and antenna height and specifying a minimum
geographic separation. Except for the
power limit, these measures are not practical in the present case. Elevated sites
are usually needed in order to obtain a
signal to rebroadcast and the transmitting apparatus must be located at the receiving site. Any predetermined geographic separation based on statistical engineering data would severely restrict the
areas in which VHF translators could he
located and limit the number to only a
few of the several hmndred devices that
are already in operation. The second
problem of interference to other services
in contiguous hands could be met by requiring refined transmitting equipment
and adequate supervision of the operation by trained radio operators. Such an
operation would he costly to install and
operate. The third problem could be met
by applying the normal measures used to
prevent interference between regular stations, i.e., limits on power, antenna
height, and geographic separation. The
practical limits of this are obvious.
4. We have decided to meet this problem by proposing transmitter power out put limited to one watt. By thus limiting the scope of any interference which
might arise we could then permit the use
of elevated antennas, reduce the performance requirements for the equipment, and
allow the routine operation of the apparatus to be carried on by a technically
unskilled operator. Even with power so
limited these devices would be capable of
causing interference, and since normal
geographic separations cannot be used,
we propose that the licensees of these devices provide full interference protection
to direct reception of all television broadcast stations, and to a limited extent to
c-ach
other. By a judicious choice of
channel and transmitter location the
problem of mutual interference between
tlnuse low power VHF translators can be
tninintized. Whenever it occurred, the
affected licensees world be expected to
settle the problem by mutual agreement
and cooperation. Interference to direct
reception of TV broadcast stations is
likely to be more serious. Such signals
are often received by UHF translators,
other VHF translators, and community
antenna systems, as well as a few private
individuals, with antennas at elevated
sites similar to those used by a VHF
translator. Since these sites are suitable
for long distance reception of TV broadcast stations they are also ideal for detection of the signals of loci power VHF
translators on other mountains. When-
ever this creates interference to direct
reception of a television broadcast station, the VHF translator would have to
cease causing interference.
5. There may be occasions when the
limit to one watt of power would prevent
a VHF translator front serving as large
an area as it might desire. In such cases,
the operation could be conducted on it
I'H F channel with higher power. The
relative absence of congestion which
makes the observance of minimum geographic separations feasible in the I'HF
band, and the fact that the UHF band is
not interspersed with other radio services, permits the use of higher power in
that band and UIIF translators may use
up to 1011 watts transmitter power output.
(I. The rules proposed herein would be
incorporated in the present rules governing television broadcast translator stations operating in the UHF television
hand. At the same time the rules governing VHF translators would be modified, where necessary, to conform with
the general principles governing this type
of operation.
7. The rules proposed herein would
not permit the use of the so-called cochannel booster amplifier. This type of
device consists simply of an amplifier
which receives. amplifies, and retransmits
at the sanie channel. Although this type
of device was used at many of the early
unlicensed stations their faults and limitations have caused them to virtually
disappear. These devices are inherently
unstable electrically. and are capable of
transmitting false and misleading signals
when operated in the VHF television
band. The Commission considers the use
of such devices under the type of relaxed
requirements contained in these rules, to
be dangerous and not in the public in-
terest.
8.
With respect to proposed VHF
translator operations in the vicinity of
the Canadian and Mexican borders, the
Commission cannot act unilaterally in
that regard. Such operation is not contemplated under the outstanding television agreements with those countries. The
Commission Will initiate action looking
to negotiations with the governments of
Canada and Mexico with a view toward
securing agreements for the operation of
these devices. Jleauwhile, if the proposed
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January, 1960
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Name
Address
City
Zone
PR E
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RAYTHEON
DISTRIBUTORS
Alabama
Birmingham
Forbes Distributing Company
Mobile
Forbes Electronic Distributors, Inc.
Arizona
Phoenix
Radio Specialties & Appl. Corp.
AL 8 -6121
Tucson
Standard Radio Parts, Inc.
MA 3 -4326
California
Burbank
Valley Electronic Supply Co.
Victoria 9 -4641
R. V. Weatherford Co.
Victoria 9 -2471
Hollywood
Hollywood Radio Supply, Inc.
HO 4 -8321
Los Angeles
Graybar Electric Company, Inc.
ANgelus 3 -7282
Kierulff Electronics, Inc.
Richmond 8 -2444
Oakland
Brill Electronics
TE 2 -6100
Elmar Electronics
Hlgate 4 -7011
San Diego
Radio Parts Company
Santa Monica
Santa Monica Radio Parts Corp.
EXbrook 3-8231
Colorado
Denver
Ward Terry Company
AMherst 6 -3181
District of Columbia
Electronic Industrial Sales, Inc.
HUdson 3 -5200
Kenyon Electronic Supply Co.
DEcatur 5800
Florida
Miami
East Coast Radio & Television Co.
FRanklin 1 -4636
Tampa
Thurow Distributors
TAmpa 2 -1885
West Palm Beach
Goddard Distributors, Inc.
TEmple 3 -5701
Illinois
Chicago
Allied Radio Corporation
HAymarket 1 -6800
Newark Electric Company
EState 2 -2950
RAYTHEON Distributors
Now Offer Semiconductors
at Direct Factory Prices
Maryland
Baltimore
Wholesale Radio Parts Co., Inc.
Mulberry 5 -2134
Massachusetts
Boston
Cramer Electronics, Inc.
COpley 7 -4700
DeMambro Radio Supply Co., Inc.
AL 4 -9000
Lafayette Radio Corp. of Mass.
HUbbard 2 -7850
Cambridge
Electrical Supply Corporation
UNiversity 4 -6300
Michigan
Ann Arbor
Wedemeyer Electronic Supply Co.
Normandy 2 -4457
Detroit
Ferguson Electronic Supply Co.
WOodward 1 -2262
Minnesota
Minneapolis
Electronic Expeditors
of Minnesota, Inc.
FEderal 8 -7597
Mississippi
Jackson
Ellington Radio, Inc.
RAYTHEON COMPANY DISTRIBUTOR PRODUCTS DIVISION WESTWOOD, MASS.
RECEIVING AND INDUSTRIAL TUBES
SEMICONDUCTOR PRODUCTS
RAYTHEON /MACHLETT POWER TUBES
VOLTAGE REGULATORS
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MECHANICAL COMPONENTS
CAPTIVE HARDWAR
SERVING KEY
MARKETS INCLUDE
Missouri
Kansas City
Burstein -Applebee Company
BAltimore 1-1155
New Mexico
Alamogordo
Radio Specialties Company, Inc.
HEmlock 7 -0307
Albuquerque
Radio Specialties Company, Inc.
AM 8-3901
New York
Mineola, Long Island
Arrow Electronics, Inc.
Pioneer 6-8686
New York City
H. L. Dalis, Inc.
EMpire 1 -1100
Milo Electronics Corporation
BEekman 3 -2980
Ohio
Cincinnati
United Radio Inc.
CHerry 1 -6530
Cleveland
Main Line Cleveland, Inc.
EXpress 1 -1800
Pioneer Electronic Supply Co.
Superior 1 -9411
Columbus
Buckeye Electronic Distributors, Inc.
CA 8 -3265
Dayton
Srepco, Inc.
BAldwin 4 -3871
Oklahoma
Tulsa
S & S Radio Supply
CHerry 2 -7174
Oregon
Portland
Lou Johnson Company
CApitol 2 -9551
Pennsylvania
Braddock
Marks Parts Company
ELectric 1-1314
Philadelphia
Almo Radio Company
WAlnut 2 -5918
Radio Electric Service Co.
WAlnut 5 -5840
Reading
The George D. Barbey Co., Inc.
FR 6 -7451
Tennessee
Knoxville
Bondurant Brothers Company
Texas
Dallas
Graybar Electric Company
Riverside 2 -6451
Houston
Harrison Equipment Company
CApitol 4 -9131
Utah
Salt Lake City
Standard Supply Company
EL 5 -2971
Virginia
Norfolk
Priest Electronics
MA 7 -4534
Richmond
Meridian Electronics, Inc.
Richmond 5 -2834
Wisconsin
Appleton
Electronic Expeditors, Inc.
REgent 3.1755
Green Bay
Electronic Exeditors, Inc.
HEmlock 2 -4165
Menasha
Twin City Electronics
Milwaukee
EX -EL Distributors, Inc.
Electronic Expeditors, Inc.
FLagstone 2 -2070
Milwaukee Electronic Expeditors, Inc.
GReenfield 6 -4144
Oshkosh
Electronic Expeditors of Oshkosh, Inc.
BEverly 5-8930
rules were adopted, applications for VHF
translators would be taken tip with the
appropriate government on a case -bycase basis.
9. The proposal tinder consideration
herein contemplates authorization, pursuant to the appended rules, of new VHF
translators. Repeater facilities installed
prior to the issuance of a construction
permit by the Commission give rise to
problems under section 819 (a) of the
Communications Act of 1934, which has
been construed to prohibit the granting
of a license authorizing the use by broadcast stations of facilities constructed before the issuance of a construction permit
by the FCC. The Commission has submitted to Congress legislative recommendations directed to this problem.
10. Authority for adoption of the rules
appended hereto is contained in sections
4 (i) , 301, 303 (a) , (b) , (c), (d), (e),
(f) , (g) (h) , (p) and (r) and 307 (b)
of the Communications Act of 1934, as
amended.
11. Any interested party who is of the
opinion that the proposed amendment
should not be adopted, or should not be
adopted in the form set forth herein, may
file with the Commission on or before
Jan. 11, 1960, a written statement or
brief setting forth his comments. Comments in support of the proposed amendment may also be filed on or before the
same date. Comments or briefs in reply
to the original comments may be filed
within 10 days from the last day for filing said original comments. No additional comments may be filed unless (1)
specifically requested by the Commission
or (2) good cause for the filing of such
additional comments is established.
U. In accordance with the provisions
of § 1.54 of the Commission's rules and
regulations, an original and 14 copies of
all statements, briefs, or comments shall
be furnished the Commission.
Proposed amendments to Subpart G,
Part
§
4:
4.701
Definitions.
Television broadcast translator
station: A station in the broadcasting
service operated solely for the purpose of
retransmitting the signals of a television
broadcast station or another television
broadcast translator station, by means of
direct frequency conversion and amplification of the incoming signals and without significantly altering any characteristic of the incoming signal other than
its frequency and amplitude, for the purpose of providing television reception to
the general public.
(b) Primary station: The television
broadcasting station radiating the signals
which are retransmitted by a television
broadcast translator station.
A television
(c) VHF translator:
broadcast translator station operating on
a VHF television broadcast channel.
(d) UHF translator: A television
(a)
January, 1960
broadcast translator station operating on
a UHF television broadcast channel.
4
4.702
Frequency assignment.
(a) An applicant for a new tele ision
broadcast translator station or for
changes in the facilities of an authorized
station shall endeavor to select a channel
on which its operation will not be likely
to cause interference to the receptor of
other stations. The application mi st be
specific with regard to the frequen y requested. Only one channel will to asW
signed to each station.
(b) An applicant for a VHF translator
station may specify any standard VHF
television broadcast channel. VHF translators are not required to observe a minimum separation from television broadcast stations operating on the cl annel
used by the translator or on an adjacent
channel. However, the use of such channels by VHF translators is secondary to
the use by television broadcast stations
and VHF translators must provide complete interference protection to reception
of existing and future television broadcast stations.
(c) An applicant for a UHF translator may specify any one of the up Jer 14
UHF television broadcast channels between 70 and 83 inclusive, provided that
the proposed translator will not be located:
(1) Within 2O miles of a television
broadcast station or city which is assigned
the second, third, fourth, fifth or eighth
channel abcive or In-low the req. tested
channel;
(2) Within 55 miles of a television
broadcast station or city which is assigned
an adjacent channel;
(3) Within 60 miles of a television
broadcast station or city which is assigned
the seventh channel above or the seventh
or fourteenth channel below the requested channel;
(4) Within 75 miles of a television
broadcast station or city which is assigned
the fifteenth channel below the req rested
channel;
(5) Within 155 miles of a television
broadcast station or city which is assigned
the same channel as the requested channel unless the proposed channel is already
assigned to the city in which the translator is to be operated, in the Table of
Assignments appearing in § 3.606 (b) of
this chapter.
(d) The distances specified in paragraph (c) of this section are to he determined between the proposed site of the
television broadcast translator station
and the Post Office location in ary city
listed in § 3.606 (b) of this chapter unless
the channel shown therein has been assigned to a television broadcast station,
in which case the distance shall be determined between the proposed site of the
translator and the transmitter site of the
television broadcast station. Changes in
the Table of Assignments of § 3.606 (b)
27,
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TELEVISION
To Fit Every
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of this chapter may be made without
regard to existing or proposed television
broadcast translator stations and, where
such changes result in minimum separations less than those specified above, the
licensee of an affected television broadcast translator station shall file an application for a change in channel assign oment to comply with the required separations.
(e) No minimum distance separation
is specified between television broadcast
translator stations operating on the same
channel. However, the separation shall
in all cases be adequate to prevent mllIual interference.
MONITORS
Application
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(f) Adjacent channel assignments will
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Iranslator stations intended to serve all
or a part of the same area.
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Complete
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promptly eliminated by the application of suitable techniques, operation of
the offending translator shall be suspended and shall not be resumed until the inbe
purposes
im
terference has been eliminated. if the
complainant refuses to permit the translator licensee to apply remedial techniques which demonstrably will eliminate
the interference without impairment of
the original reception, the licensee of the
translator is absolved of further respon-
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(c) It shall be the responsibility of the
licensee of a television broadcast translator station to correct any condition of
interference which results from the radiaion of radio frequency energy by its
equipment on any frequency outside the
assigned channel. ITpon notice by the
Commission to the station licensee or operator that such interference is being
caused, the operation of the television
1
IADDRESS:
ST
J
measures.
(d) In each instance vshoe suspension
of operation is required, the licensee shall
submit a full report to the Commission
after operation is resumed, containing
details of the nature of the interference,
the source of the interfering signals, and
the remedial steps taken to eliminate the
interference.
I um!
4.711
tics
new televi-
syill be considered to occur whenever reception of a regularly used signal is impaired by the signals radiated by the
translator, regardless of the quality of
such reception or the strength of the
signal so used. If the interference cannot
PORTABLE
., 9 n
a
translators from interference resulting
from its operation. If interference develops between VHF translators, the problem shall be resolved by mutual agrcewent among the licensees involved.
(h) It shall be the responsibility of the
licensee of a VII translator to correct at
its expense any condition of interference
to the direct reception of the signals of
a television broadcast station operating
on the sanie channel as that used by the
VHF translator or on an adjacent channel, which occurs as the result of the
operation of the translator. Interference
114/kOatt. i
translator station: Pror ided, however.
That short test transmissions may be
made during the period of suspended operation to check tli' efficacy of remedial
O
sion broadcast translator station or for
changes in the facilities of an authorized
station will not be granted where it is
apparent. that interference ss'iii be caused.
In general, the licensee of a new t'IIF
translator shall protect existing VHF
$
I
Program Failure Alarm
Audio Operated Relay
4.703 Interference
(a) An application for
broadcast translator .station shall be suspended immediately and shall not be resumed until the interference has been
eliminated or it can he demonstrated that
time interference is not due to spurious
emissions by the television broadcast
A'ISM ATIA.I: Pi(l('EDI'I {I:
Administrative procedure.
t.I I to 4.1(i inclusive.
1,1(' I ;NSIN(a
signals of television broadcast stations
may be retransmitted to areas in which
direct reception of such television broadcast stations is unsatisfactory due to distance or intervening terrain barriers.
(h) A television broadcast translator
station may be used only for the purpose
of retransmitting the signals of a television broadcast station or another television broadcast translator station which
have been received directly through
space, converted to a different channel
by simple heterodyne frequency conversion, and suitably amplified.
(c) The transmissions of each television broadcast translator station shall be
intended for direct reception by the general public and any other use shall be.
incidental thereto. A television broadcast
translator .station shall not be operated
solely for the purpose of relaying signals
to one or more fixed receiving points for
retransmission, distribution, or further
relaying.
(d) The technical characteristics of the
retransmitted signals shall not be deliberately altered so as to hinder reception
on conventional television broadcast receivers.
(e) A television broadcast translator
station shall not deliberately retransmit
the signals of any station other than the
station it is authorized by license to retransmit. Precautions shall be taken to
avoid unintentional retransmission of
such other signals.
§
4.732
Eligibility and licensing require-
ments.
(a) A license for
a
www.americanradiohistory.com
television broadcast
translator station may be issued to any
qualified individual, organized group of
individuals, broadcast station licensee, or
local civil governmental body upon an
a.ppropriatc showing that plans for fi-
BROADCAST
28
POLICIES
t 4.731
Purpose and permissible service.
(a) Television broadcast translator
stations provide a means whereby the
ENGINEERING
mincing the installation and operation Of
the station are sufficiently sound to insure continuation of the operation for the
period of the license.
(h) Alore than one television broadto
cast translator station Inlay be
the sanie applicant, whether or not such
stations serve substantially the same
area, upon an appropriate slurring of
need for such additional stations.
le) Only one channel will be assigned
to each television broadcast translator
station. Additional television broadcast
translator stations may be authorized to
provide additional reception. A scpl(rallapplication is required for each tel.visi(u
broadcast translator station and each ap
plicatiou shall be complete in all respects
4.733 (Reserved]
4.734 Remote control operation.
(a) A television broadcast translator
station may be operated by remote con
trol provided that such operation is con§
§
ducted under the following conditions:
(1) A monitoring point shall he calablishcd on premises under the control of
the licensee or its agent, within the area
served by the translator. It shall be
equipped with a television receiver ill
good operating condition and suitabl(
for observing the transmission of till
translator.
(l) An operator meeting tlll' requirements of § 4.766 5111111 observe the trans
missions of the translator at the Isom
toting point within one hour after Ile
start of any lrriod of operation and al
intervals of not more than six hours (luring operating. 'l'hc opzrotor shall prompt
ly correct any condition of impropa(
operation observed and if unable or not
qualified to do so under tit:, provisions (If
§ 4.766 (I)). shall roan:- diatel } susp: tad
operation until suitable r.1_é1:5 or adjust
!milts can be made.
(3) An entry shall b, nuu1: in th, op
crating log of the station at the time
each visit to the monitoring point is
trade showing the date and time, the
condition of operation not :d. and aon
corrective action taken.
(4) If the transmitting apparatus is
installed at a location which is lint read
ily accessible at all hours and in all seasons. means shall be provided for manually turning the transmitting apparatus
off at a point which is readily accessible
at all hours and ill all season.. The control circuit shall be so designed that fail ure of the circuit which results in loss of
control from the control point will place
the transmitter ill a non -radiating. condition.
(5) 'Flu' transmitting apparatus and
control point shall be protected against
tampering by unauthorized persons.
(6) The transmitting apparatus shall
be equipped with suitable automatic circuits which will place it ill a non-radiating condition ill the absence of an incoming signal.
RCA SALES AND PRODUCT PLANNING
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Several immediate openings are presently available to experienced engineers with Sales or Marketing interests. Our positions offer unusual
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RCA Professional Employment
Bldg. 10 -1, Camden 2, N. J.
RADIO CORPORATION OF AMERICA
Industrial Electronic Products
NEMS CLARKE
Type TRC -1
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The Type TRC -1 Color Rebroadcast Receiver has been designed specifically to
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SPECIFICATIONS
75 ohms, coaxial
Output terminal
Adjustable up to approximately I volt,
Level
peak to peak
Polarity
Sync negative
Frequency response
To 4.2 me
SOUND CHANNEL
Separate IF (not intercarrier)
Output level
Adjustable from 0 to It dbm
System
Output impedance
600 ohms or 150 ohms,
Frequency response
balanced or unbalanced
30 to 15,000 cycles with
standard 75 -u sec de- emphasis
Noise level
_
50
LARKE COMPANY
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919 JESUP.BLAIR
Len than 1%
db below -) 0 dinSYNC CHANNEL
.. 75 ohms,
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Output connection
3 volts, peak to peal
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Negative
Polarity
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Gain control
75 ohms, coach,
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Crystal controlled R.F. _.. Employed for maximunand unattended opera5or
Self-contaieec
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JUNIPER
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29
www.americanradiohistory.com
(b) An application for a new television
broadcast translator station proposing
remote control operation shall be accompanied by a showing as to the manner of
compliance with the requirements of
paragraph (a) of this section. Any proposal to change an authorized translator
from direct operation to remote control
operation shall be submitted in the form
of an application for modification of existing authorization accompanied by the
same showing of compliance.
4
4.735
Power limitations.
(a) The transmitter power output of
a VHF translator shall be limited to a
maximum of one watt peak visual Hower.
In no event shall the transmitting apparatus be operated with power output in
excess of the manufacturers rating.
(b) The transmitter power output of
a UHF translator shall be limited to a
maximum of 100 watts peak visual power.
In no event shall the transmitting apparatus be operated with power output in
excess of the manufacturers rating.
(c) No limit is placed upon the effective radiated power which may be obtained by the use of horizontally or vertically directive transmitting antennas.
§
4.736
Emissions and bandwidth.
(a) The license of a television broad-
cast translator station authorizes the
transmission of the visual signal by amplitude modulation (A5) and the accompanying aural signal by frequency modulation (F3) .
(b) Standard width television channels will be assigned and the transmitting
apparatus shall be operated so as to limit
spurious emissions to the lowest practicable value. Any emissions including intermodulation products and radio frequency harmonics which are not essential for the transmission of the desired
picture and sound information shall be
considered to be spurious emissions.
(c) Any emissions appearing on frequencies more than three megacycles
above or below the upper and lower edges
respectively of the assigned channel shall
be attenuated no less than 30 decibels
below the peak visual carrier power.
(d)
Greater attenuation than that
specified in paragraph (c) of this section may be required if interference results from emissions outside the assigned
channel.
Antenna location.
(a) An applicant for a new television
broadcast translator station or for a
change in the facilities of an authorized
station shall endeavor to select a site
which will provide a line -of -sight trans§
4.737
mission path to the entire area intended
to be served and at which there is available a suitable signal from the primary
station or stations. The transmitting
antenna should be placed above growing
vegetation and trees lying in the direction of the area intended to be served
to minimize the possibility of signal absorption by foliage.
(b) A site within 5 miles of the area
intended to be served is to be preferred
if the conditions in paragraph (a) of
this section can be met.
(c) Consideration should be given to
accessibility of the site at all seasons of
the year and to the availability of facilities for the maintenance and operation
of the television broadcast translator
station.
(d) The transmitting antenna should
be located as near as is practical to the
transmitter to avoid the use of long
transmission lines and the associated
power losses.
(e) Consideration should he given to
the existence of strong radio frequency
fields from other transmitters at the
translator site and the possibility that
such fields may result in the n transmission of signals originating on frequencies other than that of the primary
station.
EQUIPMENT
§
4.750
Equipment and installation.
(a) An application for construction
it new television broadcast
translator station or for changes in the
facilities of an authorized station shall
permit for
specify equipment which has been type
approved by the Commission.
(b) Type approval will be granted
only after tests have been made at the
Commission's Laboratory, Laurel, Mary land. Manufacturers may submit a production model for type approval and
such approval, if granted, will be considered to apply to all identical models
manufactured under that type number.
No change, either mechanical or electrical, may be made in any type approved apparatus without prior approval of the Commission upon appropriate application therefor. Type approval may be withdrawn at any time
if the apparatus fails to meet the requirements under which type approval
was granted.
(c) Type approval will be granted
only if the apparatus meets the following requirements:
(1) The frequency converter and associated amplifiers shall be so designed
that the electrical characteristics of the
incoming signal will not be altered
significantly upon retransmission except
as to frequency and amplitude.
(2) The overall characteristics of the
apparatus shall be such that:
(i) Any emissions appearing on frequencies more than 3 megacycles above
or below the upper and lower edges, respectively, of the assigned channel shall
be attenuated no less than 30 decibels
below the peak visual carrier power output.
(ii) This suppression shall be obtained
regardless of whether such emissions are
generated within the transmitting ap-
paratus or are produced by the introduction of an external signal into the input
circuits of the apparatus.
(3) The local oscillator employed in
the frequency converter shall be sufficiently stable that, subject to variations
ill ambient temperature between minus
30 degrees and plus 50 degrees Centigrade and power main voltage variations
between 85 per cent and 115 per cent of
the rated supply voltage, its frequency
will not vary from the design frequency
by more than 0.02 per cent.
(4) The overall response of the apparatus when operating at its rated
power output, as measured at the output
terminals, shall provide a smooth curve
varying within limits separated by no
more than 4 decibels within the assigned
channel: Provided, however, That means
may be provided to reduce the amplitude
of the aural carrier below those limits if
necessary to prevent intermodulation
which would mar the quality of the retransmitted picture. The overall response, measured with respect to the
peak response within the assigned channel, shall not exceed the following levels:
(i) Zero decibels on frequencies no
more than 3 megacycles from the upper
and lower edges of the assigned channel.
(ii) Minus 30 decibels on frequencies
between 3 and 6 megacycles above or
below the upper and lower edges, respectively, of the assigned channel.
(iii) Minus 40 decibels on frequencies
more than 6 megacycles above or below
the upper and lower edges, respectively,
of the assigned channel.
(5) The apparatus shall contain automatic circuits which will maintain the
peak visual power output within 2 decibels of the nominal power output when
strength of the input signal is varied
over a range of 30 decibels and which
will not permit the peak visual power
output to exceed transmitter power
rating under any condition. If a manual
adjustment is provided to compensate
for different average signal intensities
which may be encountered in various locations, provision shall be made for determining the proper setting of the
manual adjustment by means of a meter
or meter jack to measure direct current
or voltage of appropriate circuits in the
translator. If improper adjustment of
the manual control could result in improper operation of the translator, a
label shall be affixed at the adjustment
control bearing a suitable warning.
(6) The apparatus shall be equipped
with automatic circuits which will place
it in a non -radiating condition when no
signal is being received on the input
channel, either due to absence of a
transmitted signal or failure of the receiving portion of the translator. The
automatic circuits may include a time
delay feature to prevent interruptions in
the translator operation due to signal
BROADCAST ENGINEERING
30
www.americanradiohistory.com
fading or other momentary failures of
the incoming signal.
(7) The tube or tubes employed in
the final radio frequency amplifier shall
be of the appropriate power rating to
provide the rated power output of the
translator. The manufacturer shall specify the correct direct current and voltage applied to the plate of the final
amplifier tube or tubes to obtain the
rated power output. The apparatus shall
be equipped with suitable meters or
meter jacks so that the values of plate
current and voltage can be measured
while the apparatus is in operation.
(8) The transmitter shall he equipped
with an automatic keying device capable
of transmitting the call sign assigned to
the station in international Morse code
within 5 minutes of the hour and half
hour. Transmission of the call sign shall
be accomplished either by turning the
visual and aural carriers on and off in
the proper sequence or by super- imposing an audio frequency tone containing
the telegraphic identification on the carrier radiated by the translator. The
modulation level of the identifying signal shall not be less than 30 per cent of
the aural signal.
(9) Wiring, shielding, and construction shall be in accordance with accepted
principles of good engineering practice.
(d) (1) Any manufacturer desiring to
submit a translator for type approval
shall supply the Commission with full
specification details (two sworn copies)
as well as the test data specified in this
section. If this information appears to
meet the requirements of the rules, shipping instructions will be issued to the
manufacturer. The shipping charges to
and from the Laboratory at Laurel,
Maryland, shall be paid for by the manufacturer. Approval of a translator will
only be given on the basis of the data
obtained from a sample translator submitted to the Commission for test.
(2) In approving a translator upon
the basis of the tests conducted by the
Laboratory, the Commission merely recognizes that the type of translator has
the inherent capability of functioning in
compliance with the rules, if properly
constructed, maintained, and operated.
(3) Additional rules with respect to
withdrawal of type approval, modification of type approved equipment, and
limitations on the findings upon which
.type approval is based are set forth in
Part 2, Subpart F, of this chapter.
(e) The installation of a television
broadcast translator station shall be
made only by, or under the direct supervision of, a qualified electronics engineer, and any repairs or adjustment
made during or subsequent to the installation, which could result in improper
operation, shall be made by or under the
direct supervision of an operator holding
first or second class radiotelephone operators license issued by the
Commission.
(f) The choice of transmitting and receiving antennas is left to the discretion
of the applicant. In general, the transmitting antenna should be designed to
provide maximum signal over the area
intended to be served and to minimize
radiation over other areas, particularly
those in which interference could be
caused to the reception of other stations. The Commission reserves the
right to require the use of suitable directive transmitting antennas in order
to permit the assignment of the same
channel to two or more television broadcast translator stations located i the
same general area. An application for
construction permit for a new television
broadcast translator station or for
changes in the facilities of an authorized
station shall supply complete detr.ils of
the proposed receiving and retransmitting antenna systems, including an accurate plot of the field pattern of the
transmitting antenna, if directive.
Either vertical, horizontal, or circular
polarization may be used.
a valid
5
4.751
Equipment changes.
(a) No change, either mechaniml or
electrical, may be made in type ap-
proved apparatus except upon instructions of the manufacturer of the equipment, based upon Commission approval
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for the change granted to the manufacin accordance with § 1.750 (b).
(b) Formal application (FCC Fora!
346) is required for any of the following
turer
changes:
(1) Replacement of the transmitter as
a whole, except by one of an identical
type.
(2) A change in the transmitting antenna system, including the direction of
radiation, directive antenna pattern, or
transmission line.
(3) An increase in the overall height
of the antenna above ground of more
than 20 feet or which will result in an
c,verall height above ground of more
than 170 feet.
(4) A change of the control point of
a remotely controlled television broadcast translator station or any change in
the control circuits.
(5) Any change in the location of the
transmitter except a. move within the
same building or upon the saute tower
or pole, and any horizontal change in
the location of the transmitting antenna
in excess of 500 feet.
(6) A change of frequency assignment.
(7) A change of authorized operating
power.
(8) A change of the primary TY station being retransmitted.
(c) Other equipment changes not
specifically referred to above may be
made at the discretion of the licensee,
provided that the Engineer in ('barge of
the radio district in which the television
broadcast translator station is located
and the Commission's Washington. D. C.
office are notified in writing upon completion of such chang,s, and provided
further that the changes are appropriately reflected in the next application for
renewal of license of the television
broadcast translator station.
TECH N IC A L Ol'Ea A'r i ON
§
4.761
Frequency tolerance.
The licensee of
a
television broadcast
translator station shall maintain the
visual carrier frequency and the aural
center frequency at the output of the
translator within 0.02 per cent of its assigned frequencies when the primary
station is operating exactly on its assigned frequency. This tolerance shall
not be exceeded, at times when the primary station is not exactly On its assigned frequencies, by more than the
amount of departure by the primary
station.
§
4.762 Frequency monitors and measurements.
(a) The licensee of a television broadcast translator station is not required to
provide means for measuring the operating frequencies of t he transmitter.
However, only equipment having the required stability will be approved for use
at a television broadcast translator station.
(b)
In the event that a television
broadcast translator station is found to
be operating beyond the frequency
tolerance prescribed in §4.761, the licensee shall promptly suspend operation
of the translator and shall not resume
operation until the translator has been
restored to its assigned frequencies..1djustnlent of the frequency determining
circuits of a television broadcast translator station shall be made only by a
qualified person in accordance with
§4.750(d).
4.763
Time of operation.
(a) A television broadcast translator
station is not required to adhere to any
regular schedule of operation. However.
the licensee of a television translator
§
station
is expected to provide a dependable service to the extent that such is
within its control and to avoid unwarranted interruptions to the service provided.
(b) If causes beyond the control of
the licensee require that a television
broadcast translator station remain inoperative for a period in excess of 1(1
days, the Engineer in Charge of the
radio district in which the station is located shall be notified promptly- in writing, describing the cause of failure and
the steps taken to place the station in
operation again, and shall be notified
promptly when the operation is resunle(I.
(c) Failure of a television broadcast,
translator station to operate for a period
of 30 clays or more, except for causes
beyond the control of the licensee, shall
be deemed evidence of discontinuance of
operation and the license of the station
will be cancelled.
(d) A television broadcast translator
station shall not be permitted to radiate
during extended periods when signals of
the primary station are not being re-
transmitted,
Station inspection.
The licensee of a television broadcast
translator station shall make the station
and the records, required to he kept by
the rules in this subpart, available for
inspection by representatives of the
§
4.764
Commission.
§
4.765 Posting of station and operators
licenses.
(a) The station license and any other
instrument of authorization or individual order concerning the construction of
the equipment or manner of operation
shall be posted in a conspicuous place in
the room in which the transmitter is
located so that all terns thereof are
visible: Provided, That
(1) If the transmitter is operated by
remote control pursuant to § 4.734, the
station license shall be posted in the
above described manner at the control
point.
(2) If the transmitter is installed so
as to be exposed to the elements and
posting of the license would result in its
being so exposed, the license or a photo
copy thereof may be kept in the possession of the operator in charge of the
transmitter. If a photo copy is used, the
original license shall be conveniently
available for inspection by a representative of the Commission.
(b) The original of each station operator license shall be posted at the place
where he is on duty: Provided, hotrever,
That if the original license of ut station
operator is posted at another radio
transmitting station in accordance with
the rules governing that class of station
and is there available for inspection by
it representative of the Commission, a
verification card (Forst 758 -F) is acceptable in lieu of the posting of such
license: And provided, farther, however,
That if the operator in charge holds a
'restricted radiotelephone operator permit of the card form (as distinguished
from the diploma form), Ile shall not
post that permit but shall keep it in his
personal possession.
Operator requirements.
(a) The routine operation of a television broadcast translator station shall
be carried on only by a person holding a
§
4.766
valid Radiotelephone Operator Permit,
or a First or Second Class Radiotelephone Operator liczuse. 'l'he operator is
not required to continuously supervise
the operation of the transmitter but
shall observe its operation either at the
transmitter or at a monitoring point
established pursuant to the provisions of
§4.731 within one hour after the trausIll itter is placed in operation each day
and at intervals of no mare than 6 hours
during operation.
(b) Any I. pairs or adjustments to a
television broadcast translator station
'Ilia might result in improper operation of the equipment shall be matte only
l'y or '.!der the direct sup,'rvisiol of a
person bolding a valid First or Second
('lass Radiotelephone Operator license
issued by the ('onuhission.
(e) The licensed operator On duty and
in charge of a television broadcast
translator station play, at the discretion
of the licensor, be employed for other
duties or for the operation of another
station or stations in accordance with
the class of license which he holds tuul
the rules and regulations governing such
stations. However, such duties shall in
nowise interfere with the operation of
the
television broadcast
translator
station.
§
4.767 Marking and lighting of antenna
structures.
The narking and lighting of antenna
structures employed at a television
broadcast translator station, where required, will be specified in the authorization issued by the Commission. Part
17 of this chapter sets forth the conditions under which such narking and
lighting will be required and the respon-
BROADCAST ENGINEERING
32
www.americanradiohistory.com
sibility of the licensee
thereto.
§
4.768
with
regard
Additional orders.
In cases where the miles contained in
this part do not cover all phases of operation or experimentation with respect
to external effects, the Commission may
make supplemental or additional orders
in each case as may be deemed necessary.
4.769
Copies of rules.
The licensee of a television broadcast
translator station shall have current
copies of Part 3, Part 4, and Part 17 of
this chapter available for use by the
operator in charge and is expected to be
familiar with those rules relating to the
operation of a television broadcast translator station. Copies of the Commission's rules may be obtained from the
Superintendent of Documents, Government Printing Office, Washington 25,
1). C., at nominal cost.
OPERATION
§
Station records.
(a) The licensee of a television broad-
4.781
cast translator station shall maintain an
operating log showing the following:
(I) Hours of operation.
(2) Call letters, channel, and location
of primary station or stations.
(3) Time of periodic observation required by § 4.731, and operating conditions, signed by the operator making the
observation.
(4) A record of all repairs, adjustments, maintenance, tests, and equipment changes, showing the date of such
events, the name and qualifications of
the person performing the operation, and
a brief description of the matter logged.
(b) Where an antenna structure is
required to be illuminated, see § 17.38 of
this chapter.
(c) The operating log shall be trade
available, upon request, to any authorized representative of the Commission.
(d) Station records shall be retained
for a period of two years.
§
§
4.782
4.783
translator stations will be made up of
the initial letter K or W followed by the
channel number assigned to the translator and two letters. The use of the
initial letter will generally follow the
pattern used in the broadcast service,
i.e., stations west of the Mississippi
River will be assigned an initial letter K
and those east of the Mississippi River
the letter W. The two letter combinations following the channel number will
be assigned in order and requests for the
assignment of particular combinations
of letters will not he considered.
§
4.784
Rebroadcasts.
from the leader
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January, 1960
In the matter of amendment of Part
Subpart G, rules governing teleision
broadcast translator stations ( §§ 4.736
(c) and 4.750 (c) (2) and (4) )
At a session of the Federal Communications Commission held at its offices on
the 27th day of November, 1959:
The Commission has before it for consideration §§ 4.736 (c) and 4.750 (a-) of
its rules and regulations relating to television broadcast translator stations
The Commission is considering revising these standards and therefor- believes it would be desirable to extend
the period for compliance with the rules
relating to suppression of out -of -band
emissions for an additional period c one
year.
Since the amendments adopted herein
merely extend the date for comps Dance
with bandwidth limits and represent a
relaxation of the requirements by postponing the (late for compliance, gcaeral
4,
STANDS
(Reserved]
Station identification.
The call sign of a television
broadcast translator station shall be
transmitted in international Morse Code,
by means of an automatic keying device, at the beginning and end of each
period of operation and, during operation, within 5 minutes of the hour and
half hour. This transmission may be accomplished either by turning the visual
and aural carriers of the translator on
and off in the proper sequence or by
superimposing an audio frequency tone
containing the telegraphic identification,
on the visual and aural carriers radiated
by the translator. The modulation level
of the identifying signal shall not be
less than 30 1wr cent of the aural signal.
(b) The Commission may, in its discretion, specify other methods of identification.
(c) Call signs for television broadcast
TELEVISION BROADCAST TRANSLATOR
STATION
.
The term "rebroadcast" means
the reception by radio of the programs
or other signals of a radio or television
station and the simultaneous or subsequent retransmission by radio of such
programs or signals for direct reception
by the general public.
(b) The licensee of a television broadcast translator station shall not rebroadcast the programs of any television
broadcast, station or other television
broadcast translator station without obtaining prior consent of the station
whose signals or programs are proposed
to be retransmitted. The Commission
shall be notified of the call letters of
each station rebroadcast and the licensee
of the television broadcast translator
station shall certify that express author(a)
ity has been received from the licensee
of the station whose programs are retransmitted.
(c) A television broadcast translator
station is not authorized to rebroadcast
the transmission of any class of station
other than a television broadcast., or
another television broadcast translator
station.
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notice of proposed rule making, pursuant to the provision of section 4 of the
Administrative Procedure Act is unnecessary, and the amendments may become effective immediately.
Authority for the amendments adopted herein is found in sections 4 (i) , 303
(f) and 303 (r) of the Communications
Act of 1934, as amended.
In view of the foregoing: It is ordered,
That effective November 27, 1959,
§ 4.736 (c) is amended to specify Janu-
ary 1, 1961, instead of January 1, 1960,
and the notes to §§ 4.750 (c) (2) and
(4) are amended to specify January 1,
1961, instead of January 1, 1960, and
September 1, 1960, instead of September
1, 1959.
justifiably prolong the process of bringing this proceeding to the earliest possible conclusion consistent with fair opportunity for the parties to prepare and
submit comments supplementing the
voluminous record already compiled.
4. In view of the foregoing: It is ordered, That the aforementioned October
28, 1959, Motion of the Clear Channel
Broadcasting Service, is granted in part,
and the time for filing comments in response to the third notice of further proposed rule making herein is extended
from November 20, 1959, to February
19, 1960.
REALLOCATION OF CERTAIN FIXED,
LAND MOBILE AND MARITIME
MOBILE BANDS
Second Notice of Proposed Rule
Making
CLEAR CHANNEL BROADCASTING IN
STANDARD BROADCAST BAND
Order Extending Time for Filing
Comments
1. Notice is hereby given of further
proposed rule making in the above -
The Commission has before it for
consideration a Motion, filed on October
28, 1959, by the Clear Channel Broadcasting Service, for a six months extension of time, from final date of November 20, 1959, to final date of May 20,
1960, for the filing of comments in response to the third notice of further
proposed rule making in the above -entitled proceeding.
2. In support of this Motion, CCBS
states that comments have been invited
en: (a) All problems considered in this
proceeding prior to the third notice, as
these have been brought into "sharper
focus" therein, with a view toward their
final resolution; (b) a specific proposal
presented for the first time in the third
notice, whereby nighttime operations on
all of the clear channels would be modified by the assignment of unlimited time
Class II stations in designated states;
and (c) authorization of power in excess
of the present 50 kw maximum, with
consideration not limited, as heretofore,
to a particular scheme of operations on
clear channels. CCBS submits that extensive engineering studies are required
and that an extension of time at this
stage "* * * will conduce to, rather
than delay, an early and satisfactory
termination of the case by providing the
2. On April 3, 1957, the Commission
adopted a notice of proposed rule making in this proceeding which, among
other things, proposed the reallocation
of 455 -456 Mc and 460 -461 Mc from
remote pickup broadcast stations and
the Citizens Radio Service, respectively,
to the Domestic Public Land Mobile
Radio Service, in an effort to satisfy,
insofar as practicable, the stated requirements of the latter mentioned service.
The Commission believed that such an
allocation, in conjunction with the bands
already available to the Domestic Public Land Mobile Radio Service, would
have satisfied completely the stated requirements of this service except in the
larger metropolitan areas for which the
Commission is unable to find sufficient
spectrum space to fulfill the requirements without a prohibitively adverse
effect on other services. Even in those
areas, however, it was anticipated that
the reallocation would have afforded a
significant measure of relief, since the
bands which were proposed to be reallocated are immediately adjacent to
the bands 454 -455 Mc and 459-460 Mc
which are already allocated to the
Domestic Public Land Mobile Radio
1.
Commission with * * * a complete, accurate, and contemporaneous record
based on a careful compilation and expert analysis of the latest data available * * *."
3. In view of the considerable scope
of the proceeding, and of the presentation in the third notice of matters requiring detailed technical analysis, the
Commission concurs that an extension
of time is warranted. The Commission
is, however, unable to conclude that six
months of additional study are required,
and is, instead, of the opinion that an
extension of 90 days will afford ample
time for preparation of comments. Additional delay would, in our view, un-
34
entitled matter.
Service.
3. Comments submitted by the American Telephone and Telegraph Company
(AT &T) supported the Commission's
proposal to reallocate the bands 455 -456
Mc and 460 -461 Mc to the Domestic
Public Land Mobile Radio Service but
emphasized that the additional space
would be wholly inadequate to meet
their land mobile requirements in the
larger cities.
4. Comments objecting to the Corn mission's proposal in this proceeding,
with respect to frequencies available to
remote pickup broadcast stations, were
filed by the former National Association
of Radio and Television Broadcasters
(now NAB) , the National Broadcasting
Company (NBC) and the Chronicle
Publishing Company (KRON -TV) For
the most part, these objections were directed at the proposed deletion of the
455 -456 Mc remote pickup broadcast
band.
5. Electronic Industries Association
(EIA) filed a petition with the Commission, on July 10, 1958, which objected to
the proposed reallocation of a portion of
the Citizens Radio band, specifically
460-461 Mc, and requested that the
Commission issue a further notice of
proposed rule making dealing only with
the band 460 -461 Mc, to determine how
this band might be allocated to provide
for the public interest, convenience, or
necessity. Also in a separate but related
proceeding. Vocaline Company of America, Inc., filed a petition with the Commission on June 16, 1958, requesting the
Commission to terminate the proceedings in Docket No. 11994 in its entirety
and in Docket No. 11995 insofar as the
proposed reallocation of Citizens Radio
frequencies is concerned. Both of these
petitions were denied by the Commission's Second Report and Order in
Docket No. 11994 which was adopted
July 31, 1958.
6. During September 1957, Michigan
and Illinois Bell Telephone Companies
were given developmental authorizations
to operate an air -to-ground public radiotelephone service in the 450 Mc common
carrier bands, between Detroit and Chicago, for a one -year period. These authorizations were renewed for an additional year during September 1958. During July and August 1959, these Bell
companies filed applications again to renew the developmental air -ground authorizations and other affiliates sought
to extend the service to the east coast,
with ground stations at Pittsburgh,
Washington, and New York City, utilizing an additional frequency pair in the
same 454 -455 Mc and 459 -460 Mc cornmon carrier bands. The National Association of State Aviation Officials has
recommended to the Commission that
this developmental grant be made permanent and that service be expanded.
7. Subsequent to initiation of the developmental air -ground operations,
AT &T filed a petition with the Commission, on April 1, 1958, requesting that
the bands 455 -456 Mc and 460-461 Mc
be made available to the public air ground radiotelephone service. Comments filed by AT &T in opposition to
the above -mentioned EIA and Vocaline
petitions indicate that these bands
would be used for both land mobile and
air -to- ground operations. Comments generally supporting the granting of the
AT &T petition have been filed by Aeronautical Radio Inc. (ARINC) and the
AC Sparkplug Division of General Motors Corporation, and Motorola, Inc.,
filed comments opposing such a grant.
,
.
BROADCAST ENGINEERING
8. The Chicago -Detroit developmental
air -ground operations tend to indicate
a limited need for a permanent public
aeronautical radiotelephone service.
However, the extent to which air travelers, except business executives in private
planes, would avail themselves of the
new service under normal circumstances,
in view of the ever decreasing airborne
time of commercial passenger flights and
the ready availability of cheaper land line facilities at all airports is not known
at this time. Accordingly, the Commission believes that the reallocation of 2
Mc of much needed land mobile frequency space, even on a shared basis
with the land mobile service, for this
unproven service, as requested in the
AT&T petition of April 1, 1958, is not
justified and the subject AT &T petition
is denied in the concurrent Third Report
and Order in Docket No. 11995.
9. In order to meet the apparent limited need for an air-ground public radiotelephone service it is hereby proposed
that provision be made to accommodate
this service in those portions of the 454455 Mc and 459 -460 Mc bands which
are available for assignment only to stations of communication common carriers
engaged also in the business of affording public landline message telephone
service, i.e., 454.40 -455 Mc and 459.40460 Mc. It is realized that such opera-
tion of the air-ground service will require close coordination to avoid disruption of the land mobile service in these
bands, in view of the greater transmission coverage to and from airborne
units. However, it is believed that the
assignments can be arranged in such a
manner that a minimum of interference
will result since Commission records indicate that the present loading on these
bands is very light.
10. In view of the fact AT &T has indicated that implementation of the
Commission's outstanding proposal to
reallocate 455-456 Mc and 460 -461 Mc
to the Domestic Public Service would
not fill their land mobile requirement
and the Commission's belief that a full
2 Mc of valuable frequency space is not
required to adequately accommodate an
air -ground service, the original proposal,
with respect to these bands is withdrawn by the Commission's concurrent
Fifth Memorandum Report and Order
in Docket No. 11959 and Third Report
and Order in Docket No. 11995, and the
Commission proposes to reallocate the
460 -461 Mc band to the Industrial
Radio Services, which would absorb
most of the stations now operating in
this portion of the Citizens Radio band.
11. The remaining outstanding proposals in Docket 11959 to reallocate
161.645 -161.825 Mc to remote pickup
and 462.525- 463.225 Mc and 465.275466.475 Mc to the Industrial Radio
Services will be disposed of at a later
(late when appropriate.
12. In summary, the action ow- tained
herein and in the above -mer tioned
Orders:
a. Denies the AT &T petition o' April
1, 1958, which requests reallocation of
455 -456 Mc and 460 -461 Mc to an airground public radiotelephone service.
b. Withdraws the Commission's original proposal in Dockets 11959 and 11995
to reallocate 455 -456 Mc and 400 -461
Mc to the Domestic Public Land Mobile
Radio Service and terminates the proceeding in Docket No. 11995.
c. Proposes to provide for an airground public radiotelephone service in
the Domestic Public land mobile bands
454 -455 Mc and 459 -460 Mc.
d. Proposes to reallocate 460-4i1 Mc
to the Industrial Radio Services.
These actions, including the current
proposals in this docket shown in the attached appendix are not intended to
dispose of the broader considerat ons in
Docket No. 11997 with respect to finding adequate space for the Domestic
Public Land Mobile Radio Servi _e and
an air- ground public radiotel phone
service.
13. The proposed amendments to the
rules, as set forth below, are issus d pur-
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January, 1960
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35
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suant to the authority contained in sections 303 (c) (f) , and (r) of the Communications Act of 1934, as amended.
14. Any interested person who is of
the opinion that the proposed amendments should not be adopted may file
with the Commission on or before January 11, 1960, written data, views or arguments setting forth his comments.
Comments in support of the proposed
amendments may also be filed on or before the same date. Comments in reply
to the original comments may be filed
within 10 days from the last day for
filing said original data, views, or arguments. The Commission will consider all
such comments and such other material
and information as may be deemed necessary and relevant prior to taking final
action in this matter, and if comments
are submitted warranting oral argument, notice of the time and place of
such oral argument will be given.
15. In accordance with the provisions
of § 1.54 of the Commission's rules and
regulations, the original and 14 copies of
all statements, briefs or comments filed
shall be furnished the Commission.
,
INTERFERENCE STANDARD
At a session of the Federal Communications Commission held at its offices in
Washington, I). C., on the 18th (lay of
November 1959:
The Commission having under consideration the desirability of making certain changes in § 3.313 (c) of its rules;
and
It appearing that the last sentence of
the rule provides in essence that the
Commission in its discretion may assign
an FM channel different from that requested in an application; and
It further appearing that the Commission at one time utilized a Table of
Assignments of FM channels to particular communities, whereunder it could
readily determine the availability of alternative channels in a given case; and
It further appearing that the Commission by Order released August 5,
1958. effective August 20, 1958, in
Docket No. 12461 (FCC 58 -777) discontinued the use of its Table of Assignments of FM channels; and
,
It further appearing that in view of
the foregoing the Commission no longer
considers it desirable to exercise the discretionary power afforded by such rule;
and
It further appearing that questions
have arisen as to whether the sentence
in question is wholly compatible with
the intent of certain other rules such as
§§ 1.305, 1.310 and 1.356; and
It further appearing that any reason
for perpetuation of the rule has ceased
to exist; it is therefore consonant with
the public interest and orderly rule making processes to delete said sentence; and
It further appearing that the amendment adopted herein reflects a change
of procedure and thus prior publication
of Notice of Proposed Rule Making
under the provisions of section 4 of the
Administrative Procedure Act is unnecessary and the amendment may become
effective immediately; and
It further appearing that authority for
the amendment adopted herein is contained in sections 4 (i) and 303 (r) of
the Communications Act of 1931, as
amended;
It is ordered, That effective November 27, 1959, the last sentence of
§ 3.313 (e) which provides: "In the assignment of FM broadcast facilities the
Commission will endeavor to provide the
optimum use of the channels in the
band, and accordingly may assign a
channel different from that requested in
an application" is deleted.
Section 3.313 (e) will now provide as
follows:
§
3.313
*
Interference standard.
*
*
*
*
(e) Stations normally will not be authorized to operate in the same city or
in nearby cities with a frequency separation of less than 800 kc: Provided,
That stations may be authorized to operate in nearby cities with a frequency
separation of not less than 400 kc where
necessary in order to provide an equitable and efficient distribution of facilities: And provided further, That class B
stations will not be authorized in the
same metropolitan district with a frequency separation of less than 800 kc.
SUBSCRIPTION ORDER
Please place us on your subscription list.
NAME
TITLE
FIRM
ADDRESS
CITY
Rate: $6 Per Year
12
-
STATE
$7 outside U.S.A.
Issues
BROADCAST ENGINEERING, 1014
PAYMENT ENCLOSED
-; BILL LATER
Wyandotte, Kansas City 5, Mo.
".
a stereo
broadcast
not background music
.
.
is
."
ROLE OF TAPE starts on page 20
cause of the increasing competition
in broadcasting.
And now the advent of stereophonic radio opens up whole new
audiences for night -time radio.
Consider the influence stereo
broadcasts can have on night -time
revenues. Stereophonic sound in the
home is getting a tremendous lift
from our major recording companies.
There is a veritable deluge of selections in stereo.
Listeners soon realize that stereo
broadcasts can scarcely be regarded
as "background" music. It is entertainment. The enjoyment of stereo
is reserved for those hours when attentive listening is possible. Stereophonic radio performs primarily a
service for the evening hours and the
weekend.
The radio station will inherit the
role of auditioner of new stereophonic releases. Along with the routine activity of dispensing commercially- recorded music, the stations
will discover a need for a programming service which enables them to
offer one -time -only stereophonic programs designed specially for radio.
Does this mean tape networking is
just around the corner? Undoubtedly. Other than the commercial releases themselves, radio stations will
find no better source of stereo programming than the tapes they generate themselves or trade with neighboring stations or obtain through a
tape syndicate.
Cost of renting dual audio lines to
get programs from a network origination point definitely discourages
use of interconnection. So does the
technical difficulty of obtaining two
identically-matched lines for best
stereo rendition. A syndication system will reach full strength through
its unique suitability and feasibility
for the one -time -only type of programming service in stereophonic
broadcasts.
With a professional tape recorder
specifically built for stereophonic
broadcasting any station can convert
to stereo at any time, using the AMFM, TV -AM or any of the multiplexing systems. Quality of the playback and broadcast will be the finest
available.
BROADCAST ENGINEERING
36
www.americanradiohistory.com
Ivuhufkg
Senior Project Engineer
At Audio Devices
Frank
A. Co-
ne e r
at
merci has joined
Audio Devices as
senior project elng
i
t h e
Stamford, Conn..
laboratory. For
the past 12 years
Mr. Comerci has
been in charge of
the Communications and Acoustics Section at the
New York Naval Shipyard in Brooklyn, N. Y. He is a member of the
Audio Engineering Society, the Institute of Radio Engineers, the
Acoustical Society of America and
the Research Society of America. He
is chairman of the sound committee
of the Society of Motion Picture and
Television Engineers.
Technical Papers Invited for
Audio Engineering Convention
A call for technical papers for the
1960 West Coast Audio Engineering
Society Convention has been issued
by Walter T. Selsted, western vice president of the Society. 'l'he convention, expected to be the largest of
its kind ever held on the West Coast,
is scheduled for Marcia 8 to 11 at the
Alexandria Hotel in Los Angeles.
Preliminary session titles are:
Magnetic recording devices; stereo
tape reproduction and equipment;
disk recording and pickups; transistor amplifiers; loudspeakers and enclosures; stereo broadcasting and
studio input systems, acoustics, reverberation and anbiophonic techniques; audio measurements and
analysis. Authors are urged to send
titles and 25 -50 word abstracts of
their papers to Walter T. Selsted,
Ampex Corp., 934 Charter St., Redwood City, Calif.
New Literature Available
On Peak Symmetrizer
A new four -page illustrated brochure released by Kahn Research
Laboratories, Inc., 81 South Bergen
Place, Freeport, N. Y., describes
Symmetra -Peak, a passive network
January, 1960
He said the savings would come
through new accessories, adaptu=tions
and techniques in using the rec-a'der.
Nuti
IIe stated that producers preently
report economies ranging from 25 to
511 per ('('Int llndC1' filin.
widely used by AM, FINI and TV
broadcasters to increase effective
power and coverage range of voice
transmissions and to improve limiter
and AGC amplifier performance.
Folder includes specifications, customer evaluation reports and list of
users.
GPL Names Service and
New Building For
nounced by Robert Tate, director,
sales and s. rvice
division, General
Precision Laboratory, Inc. In his
new position Dr. McMahon assumes
responsibility for the areas of u:ound
support equipment, repair, spare
parts, and publications as w Il as
field service and training.
International Radio & Electronics
International Radio & Electrouics
Corp., Elkhart, Incl., has announced
a new building and two new subsidaries, Crown International, the tape
recorder division, and International
Support Manager
The appuiut nnent of Dr. Frank
A. McMahan as
manager (.: the
service and sup-
port depar ruent
Iras been an-
Latest 3M Video Tape
Radio, the broadcast equipment division. The new expansion program
will be able to triple the output of
the corporation according to company officials. Crown International
supplies tape recorders to the domestic and professional field and International Radio builds broadcast
transmitters and accessories.
Flynn Named Traffic Manager
For CBS Electronics
G. Warren Flynn has been named
traffic manager for CBS Electronics,
the electronic manufacturing division of Columbia. Broadcasting Systern, Inc. IIe studied traffic manage-
ment at Boston University and at
the College of Advanced Traffic,
Handbook Now Available
A new 60,000 -word illustrated
handbook on all aspects of video
tape has been issued by Minnesota
Iiníug & Mfg. Co. The book inaugurates a 1960 information sere _e by
3: i designed to keep users and potential users of video tape abreast of
all significant developments in this
field. Titled "The Changing Picture
in Video ' l'ape for 1959 -1960: A Review for the Television Industry"
(second edition, October, 1959) , the
book is three times as large as the
first edition. Copies may be obtained
at $1.50 each by writing Bo: No.
3500, St. Paul, Minn.
t
Dalbke Appointed Regional
Sales Manager for CBS Electronics
Warren E.
Chicago, Ill.
Dalbke has been
Day Predicts Lower TV Tape
Production Costs
Further substantial cuts
in pro-
duction costs for taped television
programs and commercials have been
promised by Bob Day, manager of
sales development for Ampex Professional Products Co. at the Los Angeles chapter of the Academy of Television Arts and Sciences. He predicted that the TV industry would
be operating with at least 30 per cent
additional below- the -line economies
ill tape production by next summer.
appointed
mid -
west regional
manager,
e(uip-
ment sales, for
CBS Electrrnics.
He previous y was
a
district
n: anag-
er, equip -nent
sales. Pri ar to
joining CBS Electronics, Mr. Rake
was a member of Armour & Co.'s
training staff. He holds a degree in
industrial education from Purdue
University.
37
". .
might have effect on
television allocation ..."
.
Induathy
Nui
SOUND POWER starts on page 14
siderably improved by operation of
all transmitters on the proposed super- accurate offset. Li the event of
improved picture channel performance by the use of these techniques,
reduction of sound channel coverage
might nullify the improved picture
coverage.
- It
Sound vs Picture Performance
is the emphatic experience of
all television receiver manufacturers
that the public will tolerate and be
entertained by extremely marginal
picture signals provided satisfactory
sound signals are available. In the
report of the first NTSC in 1941, it
is stated, "... a given amount of interference is more disturbing in the
sound than in the picture. The service area of the television systems will
be determined by the acceptability
of the service with respect to the
noise interference."
8.
-
9. Future System Development
Technological advances and improvements could conceivably make use of
the sound channel to transmit additional information. A reduction of
aural power could obstruct such possible future benefits.
In summary, any proposals for
sound power reduction should weigh
what appears to be a minor and probably short lived advantage of adjacent channel sound interference reduction against the disadvantage of
the fundamental reduction of system
capability and coverage.
The reason that TASO is interested
in the ratio of sound -to- picture power which is used in television broadcasting is that the choice of this ratio
has an effect on the extent of the
service provided by television stations and therefore might have an
effect upon the television allocation
problem. Mr. E. W. Allen, Chief
Engineer of the FCC, has stated that
the sound -to- picture power ratio
could be of significance in television
allocations (minutes of December 4,
1957, meeting of Panel Coordinating
Committee, D278, p. 3) It should
be noted that this significance extends to the general problem of television allocations and is by no means
limited to considerations regarding
"drop- ins ".
.
38
University Loudspeakers
Names President
In a joint state-
ment Alvis A.
Ward and Sidney
Levy announce(
the election of
I
Haskel A. Blair
as president of
University Loudspeakers, Inc., a
subsidiary of Ling Altee Electronics,
Inc. Mr. Levy is one of the co- founders of University, and is internationally prominent in the field of
loudspeaker engineering. Mr. Blair
has been nationally active in all
phases of the audio industry.
New RCA Plant To Be Built
A new plant for the manufacture
of RCA industrial electronic products will be constructed in the Washington- Canonsburg, Pa., area, according to T. A. Smith, executive
vice -president, Industrial Electronic
Products, RCA. The plant is the
second new Pennsylvania facility to
be announced by RCA in the past
two months. Plans call for the immediate construction of an administration and engineering building of
50,000 square feet. RCA anticipates
that future expansion will require
the construction of a manufacturing
center with 130,000 square feet of
floor space in the near future. The
site is two miles north of Washington along the Washington-Canonsburg road.
IT&T Introduces Printed
Circuit Rectifier
International Telephone & Telegraph Corp.'s Components Division,
Clifton, N. J., has introduced a series
of silicon printed circuit rectifier assemblies that can be mounted in any
desired configuration on high temperature printed circuit boards to facilitate equipment miniaturization
while providing the high output
power. The diffused -junction rectifiers employed in the assemblies are
available for single and three -phase
power supply applications, in half wave, doubler, center tap and bridge
circuits. They are hermetically sealed
and will operate in adverse environments up to temperatures of 150 deg.
C. Basic ratings are available up to
three amperes dc output and 800
volts in a single phase assembly, as
well as 4.5 amperes do in three phase
assemblies. Higher voltages and currents may be obtained by putting
the rectifiers in parallel and series.
New President Elected
At Audio Devices
William T. Hank
hais been elected
president of Audio
Devices Inc., New
York, and William
C. Speed, former
president and one
of the founders of
the company, becomes chairman
of the board. Mr.
Hack is a graduate of Princeton University with a degree in chemical engineering and also attended the Harvard Graduate School of Business
Administration.
Camera Equipment Co. Opens
Branch in Hialeah, Fla.
A completely stocked and staffed
branch in the Miami territory at
1335 East 10th Ave. has been opened
by Camera Equipment Co. with
headquarters in New York. The
branch will carry a full range of pro fessional cameras, dollies, mike
booms and perambulators, lights, incandescents, arcs, spots, brutes, generators, switches, cable, and other
accessories. A repair and service department will also be included.
Engineering Scholarship Increased
At George Washington University
The Assn. of Federal Communications Engineers at their spring
convention voted to increase the
engineering scholarship at George
Washington University from $520 a
year to $800 a year. This scholarship is awarded each year to an engineering student at George Washington University who is specializing in electrical engineering.
Houston Fearless Moves
New York Office
Houston Fearless Corp. announces
the moving of their New York regional office and showrooms to the
General Motors Bldg., 1775 Broadway, New York 19, N. Y. Houston
Fearless, whose head office and plant
are in Los Angeles, manufactures
motion picture film processors, television studio equipment, and aircraft
and missile components.
BROADCAST ENGINEERING
PtutNeut
24 db gain on the high TV channels.
A built -in power supply operates on conventional 110 -120 volt, 60 cycle current. The amplifier is protected in a steel cabinet measuring 6" x 53/e" x 4Th". It weighs 41 pounds.
and
per second, depending on the camera _model
and motor combination. It accepts the normal 400 foot magazine, and is drivez by
either a 26 volt DC or a 115 volt AC -DC
motor, depending on the model. Features include electronic flash synchronization and
exposure playback for oscillograph recorders; variable height fixed aperture :late;
two built -in NE2H timing lights; mans al or
remote camera operation; film cut -off switch
which operates an independent 20 amp load
relay and boresight focusing. The camera
with its portable power supply and car-lying
cases weighs 35 lbs. The size is 8" x 7" x 7 ".
V -6B TV RADAR BAR -DOT GENERATOR
Foto -Video Laboratories, Inc.
36 Commerce Road
Cedar Grove, N. J.
The V -6B is used to monitor and measure
the geometric distortion of TV and Radar
monitors. For television the precise two -frequency signal is produced as a composite
video signal with or without sync. The horizontal and vertical frequencies or components are chosen by a display selector to
form on a display monitor either white or
black with contrasting backgrounds: horizontal and vertical bars, vertical bars alone.
horizontal bars alone, or dot pattern. Both
horizontal and vertical bar -dot frequency
ccmponents are phase -locked to the input
sync pulses, and are independent of the input frequencies or pulse width. The V-6B
generator can be used with European and
military 405 and 625 line systems, military
and air control 875 and 945 Iine applications, as well as standard 525 line systems.
Continuously variable H and V phase controls permit the detection of short- duration
velocity errors. The operating control panel
enables rapid checks of camera geometric
distortion by matching the EIA linearity
chart pattern independent of monitor linearity. The fine white bar -dot pattern is useful
in the measurement and adjustment of the
convergence of three -color cathode ray
beams in tri-color picture tubes. The unit is
19 inches wide, 9 inches deep, and 121/4
inches high. A portable carrying case is
MARK VI -M ZOOMAR LENS
Zoomar, Inc.
Glen Cove, L. I., N. Y.
A new manually controlled zoom lens for
Vidicon Cameras has been introduced by
Zoomar, Inc. Designated the Mark VI -M, the
new lens which is a manually controlled
version of the Mark VI remote controlled unit
has a zoom range of 6:1. The lens is designed to meet the needs for operator control of closed circuit television equipment in
the fields of educational and industrial television as well as in studio operations. Resolution is 800 lines, coverage 5'8 inch diagonal, dimensions 21/2 x 21/2 x 612, weight is
11/2 lbs.
GL -7629 IMAGE ORTHICON
General Electric Co.
Schenectady, N. Y.
has
been introduced by the General Electric Co.
The new tube is physically and elect.cally
interchangeable with standard camera tubes.
It requires from 1 /10 to 1/20 the light required by standard image orthicons. It can
produce pictures of usable black -and -white
quality at one foot candle of scene illumination or less. The target uses electron conduction and the life of the tube is not limited by
the exhaustion of charged carriers. The tube
life is extended because of the lack of stickiness and burn in. Twenty -five to fift9 per
cent more resolution is claimed over pJesent
image orthicons.
A new image orthicon, type GL -7621
available.
MODEL 680 MONITOR AMPLIFIER
Fairchild Recording Equipment Corp.
10 -40 45th Ave.
Long Island City I, N. Y.
MODEL HAB TV -FM AMPLIFIER
Blonder- Tongue Laboratories, Inc.
9 Ailing St., Newark 2, N. J.
A TV -FM amplifier which boosts signals up
to 14 times for small master TV systems. The
three tube unit features a special frame grid
input circuit to provide the highest possible
signal -to -noise ratio. Maximum output is 0.7
volts at 75 ohms and 1.4 volts at 300 ohms
with 22 db gain on low TV and FM channels
This new amplifier designed for the record16
MM HIGH SPEED CAMERA
Camera Equipment Co.
315 West 43rd St.
New York 36, N. Y.
The Waddell 16 mm High Speed camera
was developed to be used where high speed
motion picture recording is necessary. It has
a speed range of from 3 to 10,000 pictures
January. 1960
ing and broadcast industries has a rated
output of 80 watts and is capable of repro-
ducing peaks in excess of 250 watts. A
meter actuated by pushbuttons on the front
panel is furnished to check output tube,
plate current, and static and dynamic balance. Input impedance is 150/160 ohm, output impedance is 8 and 16 ohms standard
with other impedances available on. special
order.
39
www.americanradiohistory.com
Pdiwf
shaping filters controlled by a three-stage
front -panel switch. The 20 -kc setting introduces a low -pass filter providing a gradual
rolloff above 30 kc, the 500-kc setting inserts
a low -pass filter that rolls off above 500 kc,
and in the 5 Mc setting a peaking network
compensates for the drop in noise output from
the gas tube at high frequencies providing
spectrum to 5 Mc.
Neun
5693 MODULATION MONITOR
Gates Radio Co.
Quincy, III.
new Gates 5693 modulation monitor
reads the true value of positive and negative peaks regardless of the presence of carrier shift. It will give correct peak indicaThe
62 AR TRANSISTORIZED POWER SUPPLY
The Doyen Co.
Livingston, N. J.
new AC to DC transistorized power supply with stability of plus or minus 0.1%
regulation for six months has been announced by the Doyen Co. The unit features
reliability of better than .95 for a period of
one year at eight hours per day, life expectancy of ten years, and an output impedance of less than 200 micro -ohms at DC.
The unit can be used as an ultra -stable
power source for precision equipment. Units
can be cascaded to provide higher voltage.
Output is 26 volts D. C. at 1 ampere.
A
re
i
tions on single program pulses as short as
approximately 50 milliseconds and will
measure the true peak amplitude regardless
of waveform. The monitor compares the rectified carrier voltage with a stabilized internal reference voltage. The monitor is designed for use with remote controlled transmitters and contains compensating adjustments for telephone line variations.
Hints
Turntable Equalizer Indicator
On many o cariuu.s the ;uutuuneeroperator would put the Gray 602
record equalizer in the roll-Off position when using a scratchy record
and then forget to turn it hack in the
regular position. This has happened
in the past for hours at a time and
can be very detrimental to building
a good listening audience.
A simple remedy, with a few hours
of work, is to put a light indicator
on the console or in any other easily
noticed spot. Take the Gray switch
box apart and remove the single section, two -pole, shorting type switch,
making certain to slake note of its
connections beforehand. Li place of
this switch use a Centralab 1424
switch which has three sections, six
poles, and five positions. Wire the
first section the same as the original.
Leave the second section unused for
possible stereo use in the future.
Wire the third section so that the indicator will light on all positions except the right one or NAB position.
NORMAN F. ROUND,
Chief Engineer, WCCM,
Lawrence, Mass.
NO. 45 COMMUNICATIONS TOWER
Rohn Manufacturing Co.
I16 Limestone, Peoria, III.
1390 -B RANDOM NOISE GENERATOR
General Radio Co.
West Concord, Mass.
An instrument capable of generating wide band noise of a uniform spectrum level suitable for many types of electrical and mechanical testing has been announced by General Radio. As a noise source it is useful for
measurement of loudspeakers, intermodulation and crosstalk tests, simulating pulse
noise in telephone line tests, noise-interference tests, dynamic range determination, and
meter response tests. A gas discharge tube
is used as a noise source; a magnetic field,
applied to the tube, serves to eliminate oscillations usually associated with a gas discharge. Noise output is amplified in a two stage amplifier, which has noise -spectrum
Advertising rates in the Classified Section
are ten cents per word. Minimum charge is
$2.00. Blind box number is 50 cents extra.
Check or money order must be enclosed
with ad.
EQUIPMENT FOR SALE
-
Demonstration
MIRATEL TV MONITORS
units, new warranty. 15 -17" metal cabinet,
$215 each. 8 -17" veneer cabinet $185 each.
Complete line of new units available in 8 ",
14 ", 17 ". 21" and 24 ". Write: Miratel, Inc.,
1082 Dionne St., St. Paul 13, Minn. 12 -59 3t
This new heavy duty communications tower
is suitable for heights up to 450 feet when
guyed every 50 feet under normal conditions. The tower is constructed in 18 inch
triangular pattern utilizing zig -zag steel
bracing, all electrically welded. The entire
10 foot tower section is hot -dipped galvan-
ized after fabrication.
Abet-Wets' Index
Atlas Sound Corp.
Bauer Electronic Mfg. Co.
Bogen- Presto Co.
Collins Radio Co.
Daven Co., The
Electro -Plex Div.,
Nuclear Electronics Corp.
Electronic Applications, Inc.
Foto -Video Laboratories, Inc.
Jampro Antenna Co
Miratel Inc.
Nems -Clarke Co.
Radio Corp. of America
Raytheon Co.
Telechrome Mfg. Co.
Television Zoomar Co.
Tower Construction Co.
33
23
25
9
35
31
2 -3
IFC
35
28
29
4 -5, 29
26 -27
IBC
BC
28
BROADCAST ENGINEERING
40
www.americanradiohistory.com
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SQUARED (SIN-)
-SQUARE WAIF
At
GENERATOR
Produces
1008 INTERVAL KEYER
1005 -A VIDEO
- Produces
composite television
waveforms suitable for measuring amplitude vs. frequency; differential gain vs
amplitude: dynamic Iinear,ly, differential
phase vs. amplitude: high frcruenry tram
sient response: low frequency transient
response: low frequency phase of streaking. smears, mismatches. and other video
1005 -A1
10(4 -B VIDEO
-RA VSMISSION
TEST SIGNAL
RECEIVER
TRANSMIZSION
TEST SIGNAL
`
MISSION TES
and accurate
eas.irenent of differenphase and differential
afn characteristics of
cry rapid
characteristics.
-
Suppiies composite EIA Sync,
blanking, horizontal and vertical drive sigregulated
B
power for itself
and
nals
and 1005-Al
nary counter
1005 -A2
cal
-
facilities Responds
standard staJstep test
gnat me dulated with 3 58
dec
Permits test and control
signals to be transmitted
simultaneously with prom material, between
es of TV picture
test signal ¡multi stairstep, color
t.
etc.) may be added
the composite pro signal. Test signals
always present for
cking transmission
ditions without i
ng picture qual
home viewer is
re of their presen
new
vape
form for testing -V r
other pulse un t or
system for amplit -e
and phase charac.eSqu;
tics. SinWave pulse is erui-rlent to TV camer 3 s gnat and is more cersitive than a Stu e-e
in
indic
Wave
ringing Video te
f
adjustable
nal
volts or 1.4 volt
-
to peak. Now ii
by major TV net
and telephone
panìes
L
LSO ASK ABOUT
mc, or any differential
phase or gain test signal.
OME SPECIAL EFFECTS GEf'ELATOR
ty.
ions & Details
Available on Request
Waveform
Generator
Remote Control
Unit
Switching
Ampl,fier
AT THE FRONT ERS OF ELECTRONICS
COLOR TV
INDUSTRIAL IVSTIUMENTATION
TELEMETRY
TELECHROME MANUFACTURING CORP.
28 RANICK DRIVE, AMITYwILL
Cable Addrecr: CfCLOR1V
=,
N. Y.
Lincoln
1
-3600
TWX: AMITYVILLE NY2314
-
106 W. St. Charles Rd., Lombard, Ill., MAyfair 7 -6026
Midwest Engineering Division
13635 Victory Blvd., Van Nuys, Ca if., STate 2-7479
Western Engineering Division
South,est.rn Division -'4207 Gaston Ave., Dallas, Tex., TAylor 3 -_291
www.americanradiohistory.com
UNIVERSAL
;lets you
ver rsing agencies an
producers wanted it -we made a close -up
adapter for the SUPER UNIVERSAL ZOOMAR.
With the camera 4 to 6 feel from the subjec #,
you z3om the entire range of 2V2 to 16 inches
with exact precision. It takes 30 seconds to
mount the adapter on the SUPER UNIVERSAL.
The wide angle shot is a medium waist shot
of announcer and product. The telephoto
shot fills the rece;ver with a
pack of cigarettes
an area
ecause
FROM
medium waist shot
TO T
a¡
...
S¡
3 inches by 4 inches.
Color Corrected
Speed
f/3
9
Zoom Rarge
SUPER UNIVERSAL
21/2 to 40 inches
Two converters
Zoom Ratio 6 to
No counterbalardng necessary
Self -Supporting
Change Zoom Range in a minute
Zoomars serviced by the Engineers who build therr
Zooma -s change from camera to camera in a minute
One year guarantee and maintenance contract
JACK A. PEGLER
BILL PEGLER
TELEVISION ZOOMAR COMPANY
500 Fifth Avenue, Romm 2223
New York 36, New Yo-k
www.americanradiohistory.com
BRyant
9 -5835
1
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