57 #559`
United States Patent
[11]
[19]
3,983,484
[451 Sept. 28, 1976
Hodama
[54] MULTICI-IANNEL SIGNAL TRANSMITTING
AND RECEIVING APPARATUS
[57] '
[75] Inventor: Takuo Hodama, Okegawa, Japan
A multichannel signal transmitting and receiving appa
[73] Assignee: Nihon Dengyo Co., Ltd., Tokyo,
ratus comprises a single reference local oscillator, a
Japan
phase locked loop including a phase comparator re
ceiving as one input a signal resulting from a fre
quency division of‘the output of the local oscillator
and a voltage controlled oscillator, a frequency divider
for supplying the output of the voltage controlled os
cillator as another input to the phase comparator, a
circuit for heterodyning a signal received through an
antenna with the oscillation outputs of the voltage
controlled oscillator and the local oscillator and there
[22] Filed:
May 9, 1975
[21] Appl. No.: 576,238
[30]
ABSTRACT
Foreign Application Priority Data
Dec. 6, 1974
Japan ...................... .. 49-146912[U]
Apr. 10, 1975
Japan ...................................... ..50-47590
after detecting the signal thus heterodyned thereby to
[52]
US. Cl ................................... .. 325/20; 325/21;
[51]
[58
Int. Cl.2 .......................................... .. H048 l/40
Field of Search .............................. .. 325/15-17,
obtain an audio signal, a frequency converter for ob
taining a carrier wave for signal transmission from the
oscillation outputs of the local oscillator and the volt
age controlled oscillator, a circuit for modulating the
325/25; 343/176
325/l9—21, 25, 18; 343/200, 175-181
[56]
carrier wave thus obtained with the audio signal and
transmitting the modulated signal through the an
References Cited
UNITED STATES PATENTS
3,201,692
3,413,554
3,487,311
3,641,434
8/1965
11/1968
3,696,422
l0/l972
3,825,830
7/1974
3,916,412
10/1975
12/1969
2/1972
tenna, a circuit forcontrollably changing over the os
cillation frequency of the local oscillator between dif
Sichak et a1. ....................... ..
Yates et al. ......................... ..
Luhowy .............................. ..
Yates et al....
.... ..
325/17
325/25
325/25
325/25
Burrell . . . . . . . . . .
325/17
. . . . ..
ferent values respectively for signal reception and sig
nal transmission, and‘v a circuit for so controllably
changing over the frequency division ratio of the fre
quency divider between different values respectively
for signal transmission and signal reception for each of
O'Connor ......................... .. 343/180
a plurality of channels. The single local oscillator is
Amoroso, Jr. . . . . . . . . . . .
. . . . ..
325/20
used for both signal reception and signal transmission.
. . . . ..
325/17
The frequency converter is provided outside of the
3,944,925
3/1976
De
3,949,296
4/1976
McClaskey et al. ................ .. 325/17
Laune . . . . . . . . . . . . . . . r
loop of the phase locked loop.
Primary Examiner—Robert L. Griffin
Assistant Examiner-Marc E. Bookbinder
.
5 Claims, 3 Drawing Figures
Attorney, Agent, or Firm—l-laseltine, Lake & Waters
31
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US. Patent
66
67
Sept. 28,-1976 v
FIG. 3
Sheet 10m
3,983,484
3,983,484 '
1
FIG. 2 is a block diagramshowing the essential orga
nization of one embodiment of a circuit of a multichan
MULTICIIANNEL SIGNAL TRANSMITTING AND
RECEIVING APPARATUS
nel signal transmitting and receiving apparatus accord
. ing to the invention; and
BACKGROUND OF THE INVENTION
5
FIG. 3 is a circuit diagram showing one embodiment
of a reference local oscillator and a delta tuning and
This invention relates generally to apparatuses for
switching circuit part.
transmitting and receiving multichannel signals and
more particularly to a multichannel signal transmitting
and receiving apparatus of the so-called transceiver
DETAILED DESCRIPTION
Referring ?rst to FIG. 1, the multichannel signal
transmitting and receiving apparatus 10 shown in per
spective view therein is provided with a front panel 11,
type capable of accomplishing transmission and recep
tion of signals of a plurality of channels of a speci?c
frequency band.
In general, in a multichannel signal transmitting and
receiving apparatus of this character, carrier waves,
local oscillation signals, and the like of frequencies
differing with the channels at the time of transmission
on which are mounted in appropriate arrangement a
number of control means. The essential control means
5 are a knob 12 for a channel selector, a knob 13 for ?ne
adjustment of the reference oscillation frequency at the
time of reception called delta tuning as described here
inafter, a knob 14 for adjustment of a squelch circuit, a
knob 15 for ON-OFF switching of the power supply
and at the time of reception are used. For this reason,
in a conventional multichannel signal transmitting and
receiving apparatus, a plurality of oscillators are used
for obtaining the signals of the above mentioned re
20 and for volume control, a meter 16, a microphone
quired different frequencies, whereby the circuit orga
nization becomes very complicated, and this gives rise
switching, an ON-OFF button switch 19 of an auto
connecting socket- 17, a button switch 18 for PA-CB
to undesirable features such as high price of the appa
ratus and dif?culty of miniaturizing the same.
noise limiter, and an indicator lamp 20.
Although not shown, an antenna connector a PA
25
SUMMARY OF THE INVENTION
loudspeaker jack socket, a power supply cord, and
other parts are provided on the rear face of the casing
21. The casing 21 houses therewithin an electrical cir
cuit described hereinbelow.
One embodiment of this circuit accommodated
Accordingly, it is a general object of the present
invention to provide a novel and useful multichannel
signal transmitting and receiving apparatus in which
the above described dif?culties and problems have 30 within the casing 21 of the apparatus 10 is shown by
been overcome.
block diagram in FIG. 2. The circuit of this embodi
Another and speci?c object of the invention is to ' ment has the circuit organization of, for example, a
provide a multichannel signal transmitting and receiv
transceiver of a double superheterodyne using the so
ing apparatus capable of carrying out transmission and
called 27 MHz citizen band of class D stations, part 95,
reception of multichannel signals by using a single ref 35 of the Rules and Regulations of the Federal Communi
erence signal oscillator. Since a single reference signal
cations Commission (F.C.C.) of the USA. In this case,
oscillator is sufficient in accordance with the apparatus
there are a total of 23 channels in class D stations, the
' of the invention, the circuit organization can be greatly
allocation frequencies of which are from 26.965 MHz
simpli?ed, whereby the apparatus can be made low-.
of the ?rst channel to 27.255 MHZ of the 23rd channel,
40 and the frequency differences between channels are of
priced and can be miniaturized.
Still another object of the invention is to provide a
a minimum of l0 KHz and a maximum of 30 KHZ and
multichannel signal transmitting and receiving appara
are 10 KHz or an integral multiple thereof.
tus having a phase locked loop including a frequency
First, the circuit system and its operation at the time
divider receiving as input a signal of a speci?c fre
of signal reception will be described.
_
quency which has been obtained by frequency division 45 A radio-frequency signal introduced through an an
from a reference frequency signal, the frequency divi
tenna 30 is supplied by way of an antenna switch circuit
sion ratio thereof being varied in accordance with a
31 to a radio-frequency ampli?er 32, where it is ampli
speci?c channel, and producing as output a signal of a
?ed and is then supplied to a ?rst frequency converter
desired frequency, and frequency converting means
33.
supplied with the output of the phase locked loop and 50 On one hand, there is provided a crystal local oscilla
the reference signal and producing as output a carrier
tor 44 caused to oscillate at a frequency of 10.240 MHz
wave at the time of signal transmission, the frequency
by a delta tuning and switching circuit 56 at the time of
converting means being provided outside of the phase
locked loop. By the organization of the apparatus of the
signal reception. This circuit 56 has switching means
operating at the time of signal transmission and the
present invention, there is no occurrence of interfer 55 time of signal reception to change over the value of a
ence of the output signal frequency of the phase locked
capacitance to be connected to the crystal of the crys
loop.
tal reference local oscillator 44 thereby to change over
Further objects and features of the invention will be
the oscillation frequency thereof to a value as de
apparent from the following detailed description when
scribed hereinafter and, in addition, a variable resistor
read in conjunction with the accompanyingdrawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
'
FIG. 1 is a perspective view of the exterior of an
60
for ?nely adjusting the oscillation frequency thereof at
the time of signal reception so as to effect accurate
matching with respect to deviation of the frequency of
the received signal.
'
The reference output oscillation signal at the time of
embodiment of a multichannel signal transmitting and 65 reception of a signal of 10.240 MHz from the crystal
receiving apparatus according to the invention as
local oscillator 44 is fed, on the one hand, to a second
viewed from a point above, to the left of, and to the
frequency converter 34 and, on another hand, by way
front of the apparatus;
of a buffer circuit 45 to a frequency divider 46, where
3,983,484
4
it is frequency divided into 'l/‘1024 and rendered into a
thermore, another portion of the output of the detector
signal of 10 KHZ. This'signal is then fed to a phase
comparator 47. This phase comparator 47 produces as
36 is supplied to the meter 16.
output a phase comparison error signal, which is fed by
successively by way of an auto noise limiter 37 having
The output audio signal of the detector 36 is supplied
way of a loop ?lter 48 to a voltage controlled oscillator
a switch 58 operable in ON-OFF switching by manipu
(hereinafter referred to as VCO) 49 thereby to control
lation of the aforementioned button 19, a volume con
the output oscillation frequency thereof.
troller 38 adjustable by manipulation of the knob 15,
The output of the VCO 49 is supplied to the ?rst
frequency converter 33 and, at the same time, by way
and a tone control circuit 39 to an audio-frequency
ampli?er 41. Between the'detector 36 and this ampli
?er 41, there is connected a squelch circuit 40 adjust
of a buffer circuit 50 to a programmable frequency
able by manipulation of the knob 14. The signal ampli
?ed by the ampli?er 41 is supplied by way of a change
divider 52, the frequency dividing ratio of which is
changed over respectively at the time of transmission
and at the time of reception by a logical control circuit
51. This logical control circuit 51 is constituted by a
over switch 42 to a loudspeaker 43 and is thereby emit
ted as sound.
The frequency division ratio of the programmable
simple logical circuit which has been arranged in pro
gramming. The frequency dividing ratio of the pro
frequency divider 52 is switched over by the channel
selection switching manipulation of the knob 12 as
described above, and a signal of a frequency necessary
grammable divider 52 is switched over to a value corre
sponding the signal reception channel by the channel
signal of 26.965 MHz will be considered. In this case,
for continually obtaining a ?rst intermediate frequency
signal of 10.695 MHz with the ?rst frequency converter
33 in accordance with the frequency of the channel
being received is generated from the VCO 49. There
fore, a ?rst intermediate-frequency signal without devi
the frequency dividing ratio of the programmable di
ation is obtained for each channel.
vider 52 is set at 1,627, and the frequency of the oscil
lation output signal of the VCO 49 becomes 16.270.
The output signal of 10 KHZ of the frequency divider
52 is supplied to the above mentioned phase compara
Next, the circuit system and the operation thereof at
the time of signal transmission will be described.
At the time of signal transmission, a button (not
shown) provided on the housing of a microphone 57 is
selection made by a channel selector 53, which is
switched over by the manipulative turning of the afore
mentioned knob 12.
Here, the reception of, for example, a ?rst channel
tor 47.
It is to be noted that the loop of the phase compara
tor 47, the loop ?lter 48, the VCO 49, the buffer circuit
50, and the programmable frequency divider 52 consti
30
pressed, whereupon the antenna‘ switch circuit 31, the
ampli?er 41, the changeover switch 42, the logical
control circuit 51, the switch-over circuit 56, and the
like are all automatically switched over to their respec- '
tive states for signal transmission.
tutes a phase locked loop (PLL). Furthermore, the
VCO 49 is adapted to oscillate at a frequency of the 35 An audio signal from the microphone is supplied
through a variable resistor 59 for microphone gain
order of 16 to 17 MHz, and its oscillation frequency is
adjustment to the audio frequency ampli?er 41 where
so locked by the PLL that the output signal of the
it is ampli?ed, and the signal thus ampli?ed is then fed
programmable frequency divider 52 is always of a fre
by way of the change-over switch 42 to an amplitude
quency of 10 KHz.
The output oscillation signal of 16.270 MHz of the 40 modulator comprising a driver and power ampli?er 55,.
On the other hand, the crystal local oscillator 44 is
VCO 49 is supplied as a ?rst local oscillation frequency
switched and set to oscillate at a frequency of
to the aforementioned ?rst frequency converter 33,
10.238102 MHz by the switch-over circuit 56. The
and from the frequency converter 33, a first intermedi
output oscillation reference signal of the osicllator 44 is
ate-frequency signal of 10.695 MHz of the difference
supplied to a frequency converter 54 of the transmis
between the 29.965 MHz and the 16.270 MHz is de
sion section and, at the same time, is supplied to the
rived. This ?rst intermediate-frequency signal is sup
phase comparator 47 after being rendered into a signal
plied to the second frequency converter by the signal of
of a frequency of approximately 9.998146 KHz upon
10.240 MHz from the crystal local oscillator 44, and a
being frequency divided by l/ 1024 by the frequency
second intermediate-frequency signal of 455 KHZ is led
‘
50 divider 46.
out from the frequency converter 34.
Furthermore, the programmable frequency divider
Similarly, in the case where, for example, a signal of
52 is so set by the logical control circuit 51 as to assume
27.255 MHz of the 23rd channel is to be received, the
the frequency division ratio at the time of signal trans
frequency division ratio of the programmable fre
mission. Accordingly, in the case where the ?rst chan
quency divider 52 is caused to be 1,656 by the switch
ing selection of the channel selector 53. As a result, the 55 nel, for example, is selected by the channel selector 53
actuated in switch-over operation by manipulation of
output oscillation frequency of the VCO 49 becomes
the knob 12, the frequency division ratio is caused to
16.56 MHz. Consequently, a ?rst intermediate-fre
be 1,673. Consequently, the frequency of the oscilla
quency signal of 10.695 MHz is similarly led out of the
tion outputsignal of the VCO 49, whose oscillation
frequency converter 33, and a second intermediate-fre
quency signal of 455 KHZ is led out of the frequency 60 frequency is controlled by the output of the phase com
parator 47 becomes 16.726898 MHz.
converter 34.
The oscillation output signal of the VCO 49 is sup
The second intermediate-frequency signal from the
plied to the frequency converter 54, and a signal of a
frequency converter 34 is ampli?ed by an intermedi
frequency of 26.965 MHz, which is the sum of the
ate-frequency ampli?er 35 and then supplied to a de
tector 36 where it is detected or demodulated and 65 frequency of the oscillation signal from the crystal local
rendered into an audio signal. A portion of the output
of the detector 36 is supplied to the ampli?ers 32 and
oscillator 44 and the oscillation signal frequency from
the VCO 49, is led out from the frequency converter
35, and automatic gain control is accomplished. Fur
54.
'
-
3,983,484 '
This carrier wave of 26.965 MHz for the ?rst channel
respect to the 12th channel, for example, becomes
is amplitude modulated in the amplitude modulator 55
zero, the maximum carrier wave frequency deviation
with respect to all channels can be held within i 0.0001
percent, and even higher accuracy is attained.
by the audio signal supplied from the ampli?er 41 by
way of the above mentioned changeover switch 42, and
one portion of the ?rst channel amplitude modulated
wave thus obtained is supplied to the meter 16, where
its level is indicated, and, at the same time, passes
through the antenna switch circuit 31 to be transmitted
As described above, by merely shifting the oscillation
frequency at the time of signal transmission of the crys
tal local oscillator 44 by approximately 1.9 KHz, for
example, toward the low side with respect to the oscil
lation frequency at the time. of signal reception, fre
from the antenna 30.
In the case where a signal of the 23rd channel, for 10 quency conversion can be carried out with zero fre
quency deviation at the time of signal reception, and,
example, is to be transmitted, a similar operation is
moreover, a carrier wave frequency for transmission
carried out. The frequencydivision ratio of the pro
can be obtained at the time of signal transmission with
grammable frequency divider 52 is set at 1,702 by the
a very small frequency deviation of the order of i
selection of the 23rd channel of the channel selector
0.0001 percent to i 0.0002 percent as a maximum.
53, whereupon the output oscillation frequency of the
Since only a single crystal local oscillator is sufficient,
VCO 49 becomes 17.016845 MHz. Consequently, the
frequency of the output carrier wave signal of the fre
quency converter 54 becomes 27.254947 MI-Iz.
It is to be noted in this connection that the normal
carrier wave frequency at the time of signal transmis
sion of the 23rd channel is determined at 27.255 MHz,
but, with respect to this, the carrier wave frequency
obtained in the above described manner differs by a
mere 53 Hz, and a deviation of this order can be amply
the circuit is of a simple organization and can be pro
duced at low cost.
Furthermore, the frequency converter 54 is not pro
vided with the PLL comprising the phase comparator
47, the loop ?lter 48, the VCO 49, the buffer circuit 50, >
and the programmable frequency divider 52 but is
provided outside of this loop. For this reason, interfer
ence of the frequencies generated at the time of signal
allowable in actual practice. Furthermore, this devia
tion is 0.0002 percent, which is amply within the stan
dard limiting speci?cation of i 0.005 percent for fre
25 transmission and at the time of signal reception can be
quency deviation of the F.C.C. of the U.S.A.
Here, the manner in which the frequency of the crys
which control of the‘ oscillation frequency of the VCO
49 is possible, stable operation can be accomplished.
tal local oscillator 44 and the frequency division ratio
of the programmable frequency divider 52 at the time
of signal transmission will described.
The carrier wave frequency of the ?rst channel being
Next, one embodiment of a speci?c circuit in con
crete form of a circuit part including the above de
eliminated. Furthermore, since the frequency range of
operation as a PLL is expanded to the range within
scribed reference local oscillator 44 and delta tuning
and switch-over circuit 56 will be described with refer
ence to FIG. 3. In this circuit, a parallel connection of
26.965 MHz, the following relationship between the
oscillation frequency fVCO of the VCO 49 and the oscilé 35 a variable capacitance diode 61 and a capacitor 62 is
connected in series to a crystal 60. To the junction
lation frequency fun; of the crystal local oscillator 44 is
between the variable capacitance diode 61 and the
obtained.
crystal 60, the emitter of a transistor 64 is connected
through a coil 63. The base of the transistor 64 is con
fLUC +fv0¢ = 26.965 MHZ
40 nected to the slidable contact of a variable resistor 65.
Furthermore, in the phase comparator 47, the follow
ing equation is valid.
(fwd/(1024) = thew/(N1) ( = 10 KHZ).
At the time of signal reception, a positive voltage is
not impressed on a terminal 66 connected to the paral
(2)
45
where N, is the frequency division ratio of the program
mable frequency divider 52 at the time of signal trans
mission of the ?rst channel. From the above Eqs. (1)
and (2), the frequency fLOC becomes
fm= (26.965 x 1024)/Nl + 10“
When the integral value of N1 which will cause fLOC to
assume a value nearest 10.240 MHz is determined,
N, = 1,673, and
fun; = 10.238102 (MHz)
are obtained.
lel connection of the variable capacitance diode 61 and
the capacitor 62 on the side opposite from the crystal
60, which is in a state wherein the capacitance of the
variable capacitance diode 61 and the capacitance of
the capacitor 62 are connected in parallel thereto, and
a reference oscillation output of 10.240 MHz is led out
through a terminal 67 as described above.
In many cases, at the time of signal reception, the
reception frequency has been slightly offset from the
frequency of the (speci?ed channel. In such a case,
therefore, the resistance value of the variable resistor
65 is adjustably varied by turning the knob 13. As a
55 consequence, the emitter voltage of the transistor var
ies, and the voltage impressed on the variable capaci
tance diode 61 varies, whereby the capacitance value
of this diode 61 changes. As a result, the oscillation
frequency of the crystal oscillator is ?nely adjusted in a
In the above described embodiment, the oscillation
continuous manner.
frequency of the crystal local oscillator 44 is so set that
At the time of signal transmission, on the other hand,
the deviation of carrier wave frequency with respect to
a positive voltage is impressed on the terminal 66 when
the ?rst channel will be zero at the time of signal trans
the button provided on the aforementioned micro
mission. For this reason, the carrier wave frequency
phone 57 is pressed. Consequently, the variable capaci
deviation of the 23rd channel is the maximum ( —53 Hz 65 tance diode 61 is rendered conductive, and, in actual
). However, by so selecting the oscillation frequency of
ity, a capacitor is no longer connected to the crystal 60,
the crystal local oscillator 44 at the time of signal trans
whose oscillation frequency decreases. Then, as de
mission that the carrier wave frequency deviation with
scribed above, an oscillation frequency of 10.238102
3,983,484
8
2. A multichannel signal transmitting and receiving
MHz is led out from the terminal 67 as described
above.
apparatus as claimed in claim 1, in which the means for
While in the above described embodiment, ampli
obtaining the carrier wave for signal transmission is
tude-modulated waves of a both side-band system are
provided outside of the loop circuit of the phase locked
loop and comprises a frequency converter for carrying
used for signal transmission and reception signals, the
out frequency conversion with the oscillation outputs
of the local oscillator and the voltage controlled oscilla
present invention is not so limited, it being possible to
use
frequency-modulated
waves
or
amplitude
modulated waves of a single side band (SSB) system.
Further, this invention is not limited to these embodi
ments but various variations and modi?cations may be
made without departing from the scope and spirit of the
invention.
What is claimed is:
tor.
3. A multichannel signal transmitting and receiving
l. A multichannel signal transmitting and receiving
apparatus comprising:
15
apparatus as claimed in claim 1 which is adapted for
use in signal transmission and reception of 27 MHZ
class D stations of the citizen band, and in which: the
local oscillator oscillates at the time of signal reception
with a frequency of 10.240 MHz, thereby to obtain a
second intermediate-frequency signal; the frequency
a single reference local oscillator producing a signal
division ratio of the ?rst frequency divider is 1,024; the
of an output oscillation frequency;
voltage controlled oscillator generates a signal, of a
a ?rst frequency divider for dividing said output os
frequency in accordance with a desired signal recep
cillation frequency with a speci?c frequency divi
tion channel, which is necessary for frequency convert
20
sion ratio and producing an output;
ing the reception signal of the desired chanel, and ob
a phase locked loop circuit having a phase compara
taining a ?rst intermediate-frequency signal; and the
tor receiving at one input thereof said output of the
frequency division ratio of the second frequency di
?rst frequency divider and producing an output,
vider is so selected that said second frequency divider
and a voltage controlled oscillator producing an
will
produce as output a signal of a frequency of 10
output of an oscillation frequency controlled by 25 KHz.
said output of the phase comparator;
a second frequency divider for frequency dividing the
4. A multichannel signal transmitting and receiving
apparatus as claimed in claim 3, in which the local
oscillator is so controllably changed over by the ?rst
changeover means at the time of signal transmission as
to oscillate with a speci?c frequency F differing by a
output of the voltage controlled oscillator with a
frequency division ratio in accordance with each of
a plurality of channels to produce a corresponding
output and supplying said corresponding output as
frequency of the order of one to a few KHz from
10.240 MHz; the second frequency divider is so con
another input to the phase comparator;
means- for subjecting a signal received through an
antenna to heterodyning by the oscillation output
of the local oscillator and the oscillation output of
the voltage controlled oscillator and thereafter
trollably changed over by the second changeover
35 means as to accomplish frequency division with a fre
quency division ratio of a value differing from the value
corresponding to each channel at the time of signal
detecting the resulting signal, thereby to obtain a
?rst audio signal;
reception, thereby to cause the value resulting from the
frequency
division of the oscillation output of the volt
means for obtaining a carrier wave for signal trans
age
controlled
oscillator to become equal to F/1,024;
40
mission from the oscillation outputs of the local
and
the
means
for
obtaining the carrier wave for signal
oscillator and the voltage controlled oscillator;
transmission
produces
as output, from the outputs of
means for modulating said carrier wave for signal
the
local
oscillator
and
the voltage controlled oscilla
transmission with a second audio signal and trans
tor,
a
carrier
wave
output
approximating the carrier
mitting the same through the antenna at times
when said heterodyning means receives no antenna 45 wave frequency of a speci?c channel with a deviation
of a maximum of a number of tens of Hz relative to the
output signal;
carrier wave frequency of said speci?c channel.
?rst changeover means for controllably changing
5. A multichannel signal transmitting and receiving
over the oscillation frequency of the local oscillator
between different values respectively for signal
reception and transmission; and
second changeover means for controllably changing
apparatus as claimed in claim 1, in which the local
50
changeover means comprises means for switching over
a capacitance connectedto-the crystal oscillator be
over the frequency division ratio of the second
frequency divider between different values respec
tween a value for signal reception and a value for signal
transmission.
tively for signal transmission and reception for
each of said channels.
oscillator comprises a crystal oscillator, and the ?rst
55
60
65
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