HP 3780A User's manual

HP 3780A User's manual
 OPERATING AND SERVICE
ANUAL
EEE EEE
HEWLETT
PACKARD
CER
Hewlett-Packard Company certifies that this product met its published specifications at the time of
shipment from the factory. Hewlett-Packard further certifies that its calibration measurements are
traceable to the United States National Bureau of Standards, to the extent allowed by the Bureau's
calibration facility, and to the calibration facilities of other International Standards Organization
members,
This Hewlett-Packard instrument product is warranted against defects in material and workmanship
for a period of one year from date of shipment. During the warranty period, Hewlett-Packard Com-
pany will, at its option, either repair or replace products which prove to be defective,
For warranty service or repair, this product must be returned to a service facility designated by HP.
Buyer shall prepay shipping charges to HP and HP shall pay shipping charges to return the product to
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from another country.
HP warrants that its software and firmware designated by HP for use with an instrument will execute
its programming instructions when properly instalied on that instrument. HP does not warrant that the
operation of the instrument, or software, or firmware will be uninterrupted or error free.
LIMITATION OF WARRANTY
The foregoing warranty shall not apply to defects resulting from improper or inadeguate maintenance
by Buver, Buyer-supplied software or interfacing, unauthorized modification or misuse, operation out-
side of the environmental specifications for the product, or improper site preparation or maintenance.
NO OTHER WARRANTY IS EXPRESSED OR IMPLIED. HP SPECIFICALLY DISCLAIMS THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE. a
EACLUSIVE REMEDIES
THE REMEDIES PROVIDED HEREIN ARE BUYER'S SOLE AND EXCLUSIVE REMEDIES. HP
SHALL NOT BE LIABLE FOR ANY DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CON-
SEQUENTIAL DAMAGES, WHETHER BASED ON CONTRACT, TORT, OR ANY OTHER LEGAL
THEORY,
Product maintenance agreements and other customer assistance agreements are available for Hevlett-
Packard products.
For any assistance, contact your nearest Hewlett-Packard Sales and Service Office. Addresses are /
provided at the back of this manual. RA
Гл HEWLETT
PACKARD
OPERATING AND SERVICE MANUAL
3780A ВЕ
PATTERN GENERATOR/ERROR DETECTOR
(Including Options 001,002,003,099,100,101and 102)
SERIAL NUMBERS
This manual applies directly to instruments
with serial numbers prefixed 20200.
With changes described in section VII this
manual! also applies to instruments with serial
numbers prefixed 1520U to 2006U,
For additional important Information about
serial numbers see iNSTRUMENTS CO-
VERED BY MANUAL in section |.
© Copyright HEWLETT-PACKARD LIMITED 1981
SOUTH QUEENSFERRY, WEST LOTHIAN, SCOTLAND
MANUAL PART NUMBER 03780-90023
1 Microfiche Part Number 03780-90048
Printed: March 1981
Model 3780A
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Figure 1-1 The 3780A Pattern Generator/ Error Detector
General Information
SECTION |
GENERAL INFORMATION
1-1. INTRODUCTION
1-2. This Service Manual contains the information necessary
to install, operate and maintain the Hewlett-Packard Model
3780A Pattern Generator/Error Detector. The instrument
and accessories supplied are shown in Figure 1-1.
1-3, This manual is available in 6 x 4 inch Microfiche each
containing up to 95 photo duplicates of manual pages.
The Microfiche package includes the latest Manual Change
Supplement and all pertinent Service Notes. The part
numbers of this manual in microfiche form, as given on
the title page, should be quoted when ordering.
1-4, An Operating Manual is also supplied with this in-
strument and should be kept with the instrument for use
by the operator.
1-5. SPECIFICATIONS
1-6. The specifications of this instrument are listed in
Table 1-1. These specifications are the standards against
which the performance of the instrument is tested (see
section IV of this manual).
1-7. SAFETY CONSIDERATIONS
1-8. This Service Manual contains information, cautions
and warnings which must be followed to ensure safe opera-
tion and to maintain the instrument in a safe condition.
1-9. INSTRUMENTS COVERED BY MANUAL
1-10. The contents of this manual apply to instruments
with serial numbers as specified on the title page. The in-
SERIAL
NUMBER SERIAL
PREFIX \ / NUMBER
Figure 1-2 Serial Number Plate -
strument serial number is given on a serial number plate
as shown in Figure 1-2. This plate is located on the rear
panel of the instrument. The serial number is in two parts
The first four digits and the letter are the serial prefix and
the last five digits are the suffix. The whole serial number,
prefix and suffix should be quoted in any correspondance
regarding the instrument.
1-11. An instrument manufactured after the printing of
this manual may have a serial number prefix that is not
listed on the title page. This unlisted serial number pre-
fix indicates that the instrument is different from those
described in this manual. A blue Manual Changes supple-
ment supplied with this manual provides information on
how to adapt the manual for such instruments.
1-12. In addition fo change information, the supplement
may contain information for correcting errors in the
manual, To keep the manual as accurate as possible Hew-
lett Packard recommend that periodic requests for the
latest Manual Change supplement are made to one of the
Sales and Service offices listed at the rear of this manual.
1-13. For information concerning a serial number prefix
which is not listed on the title page or in the Manual
Change supplement contact the nearest Hewlett Packard
office.
1-1
Model 3780A
Table 1-1 Specifications
Notes: Al! transition times relate to 10 to 90% of pulse height,
All pulse widths specified at 50% of pulse height,
PATTERN GENERATOR
Internal Clock Frequency:
Accuracy!
Stability:
Format:
Jitter:
Clock Offset
Range:
External Clock Frequency:
Impedance:
Triggering:
Sensitivity:
Amplitude:
indicator:
Clock Output Polarity:
Impedance:
Amplitude:
DC Offset:
Transition
Times:
Overshoot:
Protection:
Patterns
Three crystal clocks
1536, 2048 and
8448k Hz.
Better than + 3ppm
at ambient.
Typically better than
+ 12ppm 09C to 55°C.
Typically better than
+ Sppm/vear ageing.
Square wave, 50 +
6% duty cycle,
Less than (0.5% of
period + 150 ps)
pk-pk;
Continuously variable
up to at least + SOppm
about instalied crystal
frequencies; offset
can be displayed in
recelver,
Data Format
1kHz — SOMHz,
75 ohms nominal to
ground.
Automatic or ground
threshold switch, min
pulse width (30% of
period + 2 ns).
Better than 500mV
nk-pk.
5V pk-pk max. limits
+ 5V.
LED illuminated if
ciock transitions pre-
sent.
Data Output
CLOCK or CLOCK
switch,
75 ohms nominal to
ground.
3V 2 0.3V рк-рк.
Space OV, mark 3V.
Less than 4ns.
Less than 10% of
pulse amplitude,
Gpen/short circuit
protected, max voi
tage = AY short term.
PRBS:
WORD:
Zero Add:
Error Add:
Binary:
Ternary:
Codes:
Impedance:
Amplitude:
DC Offset:
Transition
Times:
Overshoot:
Protection:
Maximal length 2 | ,
25.1, 2%..1. Rap
domiy selectable ©,
15. 20 bit sequences.
0006, 1000. 1010,
1100, 1111 fixed
words,
1-999 zeros, variable
in unit steps, may be
added once per se-
quence to any pattern,
Zero block occurs be-
fore longest run of
zeros in maximal length
PRES.
10-* binary error
rate may be added fo
any pattern (19 con»
secutive errors added
every 1000 ciock per-
10485).
NRZ or RZ (50 36%
width on internal
clock).
RZ AMI or coded
{50 £ 6% width on in-
ternal clock).
HDB3 or HDB? (rear
panel switch),
75 ohms nominal to
ground.
Binary 3V £0.3
pk-pk.
Ternary 4.74V ©
0.47Y pk-pk.
Binary space OY, mark
3V.
Ternary space OY,
mark 2.37Y,
Ratio of +ve to —ve
pulse amplitude 1.0
+ (0.05,
Less than dns,
Less than 10% of
puise amphiude.
Open/short circuit
protected, max. vol-
tage T 6V short term.
1-2
Table 1-1 Specifications (continued)
General Information
Format:
Relative
Delay:
Delay Data
Output
DC Offset:
Binary oniv. Data Format
6 bits advanced on
main data output.
Binary space OV =
0.3Y, mark ЗУ ©
0.3Y.
Other specifications as for main data
output.
Clock/Data NRZ Data:
Phasing
RZ Data:
Format:
Trigger Output
Position:
Width:
Impedance:
Amplitude:
Transition
Times:
Overshoot:
Protection:
ERROR DETECTOR
Data Input Rate:
Impedance:
Triggering:
Sensitivity:
Amplitude:
Indicator:
Rising edge of clock
nominally in middie
of data.
Clock and data nomi-
nally coincide.
Clock Recovery
Square wave with one
transition per word
or sequence.
Transitions nominally
coincident with start
of word or before
first zero of longest
zero block in PRBS.
Equal to word or se-
quence length, but
output held at zero
during zero add
50 ohms nominal to
ground.
1V pk-pk min.
Less than 5ns.
External Clock
Less than 10% of
puise amplitude.
Open/short circuit
protected, max vol-
tage + 5V short term.
1 Kb/s — 59Mb/s,
75 ohms nominal to
ground.
Choice of nominal
threshold 200mV,
600mV, or ground;
min puise width
(30% of period +
2ns).
Better than 500mV
pk-pk..
5V pk-pk max, limits
+ 5V.
LED illuminated if
data transitions pre-
sent,
Clock/Data
Phasing
Binary:
Ternary:
Codes:
Freguency:
Mode:
Frequency:
Polarity:
Impedance:
Triggering.
Sensitivity:
Amplitude:
Indicator:
Recovered
Clock:
External
Clock:
NRZ ог RZ,
RZ AMI or coded.
HDB3 or HDB? {rear
panel switch common
with generator).
At the three internal
rates of generator
(selection switch com-
mon with generator).
Operates on any data
input provided there
are two or more tran-
sitions every 20 bits
(data loss inhibits
clock recovery cir-
cuit}
1kHz — SOMHz.
CLOCK or CLOCK
switch.
75 ohms nominal to
ground,
Automatic or ground
threshold switch (com-
mon with generator),
min pulse width
(30% of period +
2ns).
Better than 500mV
pk-pk.
5V pk-pk max, limits
SV.
LED illuminated if
clock transitions pre-
sent:
Automatic phasing.
Rising edge of ciock
should be nominally
in middle of data
puise {typically 3ns
internal delay of clock
relative to data bet-
ween inputs and sam»
pling point).
1-3
Model 3780A
Table 1-1 Specifications (continued)
Patterns
Synchronisation
Measurements
PRBS and
WORD:
Indicators:
Mode:
Sync Loss:
Manual:
Resync Time:
Modes:
BINARY
ERRORS:
CODE
ERRORS:
AMI:
HDB3:
HD B3/
HDB2:
HDB2/
BIZS:
B6ZS:
AI patterns produced
by generator exchid-
ing added zeros and
alternating words; re-
Display
BER
LE indication of pat-
tern nck for PRBS,
PES WORD and AIS
(леса! эт inhibited
during sync loss and
code error ar tre-
quency offset meas-
urements).
Automatic with mar
ual override.
Greater than approx.
20,000 errors in
500,000 clock periods.
Sync override via push
button forcing a sync
loss.
Typically less than
500 bits.
Binary errors, code
errors, frequency off-
set.
Closed icop bit-by-bit
détection on any pat-
tern produced by
generstor excluding
added zeros and aiter-
nating words.
Violations of coding
rule detected on any
pattern according to
the following rules
where 0= space | = mark
Y = bipolar violation:
Bipolar violations are
code errors.
G1V, 10V,11VW,
$000 and 0100V are
code errors.
Violations of violations
selectable with an inter-
nal switch.
IV, 806 and 610V
are code errors,
Ovo, 1VO, IVE 06VH
and 000000 are code
errors (see options);
(0GGGOOV1 and
200000 VO are counted
as single errors),
Display
COUNT
STROBING
FREQUENCY Measurement of frac-
OFFSET:
tional offset of gener-
ator clock output from
installed crystal rates.
FREO, OFFSET
Method:
Gating:
Format:
Range:
Accuracy:
Method:
Gating:
Format:
Range:
Method:
Gating:
Format:
Range:
Accuracy:
BER & FREQ
OFFSET:
COUNT:
Totalises errors over
selected gating period
and automatically
scales the answer,
10%, 16% or 10
clock periods, repet-
itive.
107? {code errors
over 10'%lock periods),
00x 1077 to 1.0 x
109 (code errors
over 10% clock periods),
0.0x 10710 1.0x
10 (code errors
over 10 clock periods).
indication given if
measurement result
based on less than
100 errors.
Totalises errors over
selected gating periods.
Manuat start/stop
pushbutton switches.
External control via
printer output.
X.Y x 10"" LED
with automatic round-
up.
0.0 x 10'to9.9 x 10°
Counts deviation fre-
quency over 10° clock
periods of internal
standard crystal rate.
Automatic,
XY x 1079 with auto-
matic round-up
Up to 25kHz deviation
from nominal crystal
rate.
+ ] count relative to
the internal standard
clocks,
Display strobed at
end of gating interval:
maximum refresh-
ment rate 2 Ну.
Display continuously
updated with round-
up when measure-
ment ends,
Table 1-1 Specifications (continued)
General information
Flags (LED's)
Printer Gutput
{rear panel)
Crating:
Sync Loss:
Overflow:
< 100 Errors:
Format:
Flags:
Print Modes:
Indicutes invasture-
ment in progress, will
extinguist for al least
>G0ms hetween
Vos roe nts.
Inmdiales local paí»
tora reference has lost
sync: display blanks
and measurement is
terntinated (BER) or
halted (COUNTY; fag
remains it for at least
Sms (BER) or
held (COUNT) until
measurement is ter-
minated.
{Sync loss inhibited
during code error and
frequency offset
measurements).
Indicates internal error
or frequency count
107: display blanks
and measurement 1$
terminated (BER) or
halted (COUNT);
flag remains lit for at
least 500ms {BER}
or held (COUNT) until
measurement is ter
minated.
indicates less than 100
errors counted during
last error measure-
ment {inhibited dur-
ing frequency offset
measurements).
(rear panel)
84721 BCD 10 columns
BER F*X *¥ *10 ~~ №
COUNT FFX *Y *I0+ N
r= Y for <100 errors
F=1 {for overflow
F= 2 for sync 1088
F = 3 for clock toss
F=4 for data loss
pu À for AIS
BER — print command
given on termination
of measurement.
COUNT MAN — print
command given on
STOP command from
front panel,
COUNT EXT — print
command given on
STOP command from
printer.
Error Output
{rear panel)
Recorder Output
Print
Command: TTL pulse, min.
print cycle time 500
ms.
Format: Current source with
SOOms mimmum
response,
impedance: Greater than 50K
ohms.
Range: imA variation over
16 levels into 10K
ohms max.
BER: Thirteen level signal
LEVELS BER
SD 15 <1075
14 <1077
13 <1075
12 <10
11 <107°
10 <103
9 <r07?
8 <10 }
7 <107°
6 = 10"
4 Sync Loss
2 AS
0 Signal Loss
СОВЫ: Five level signal
LEVELS REFERENCE
FED 15 Signal no
CIFOFS except
7 Signal plus AIS
SHOTS
4 Sync loss
2 AS
О signal Loss
Note: when using recovered clock,
signal loss = data loss:
when using external clock,
signal loss = clock loss.
Calibration: Two rear panel push
buttons giving FSD
and Zero. Internal ad-
justment of range ImA
+ 0.2mA and centering
OmA to §.5mA.
Format: One pulse per error
(inhibited during sync
loss).
impedance: 50 ohms nominal to
ground.
Amplitude: 1Y pk-pk min,
Transition Less than dns.
Times:
Overshoot: Less than 10% of
pulse amplitude.
Model 3780A
Table 1-1 Specifications (continued)
Иа
Protection: Open/short circuit Dimensions 195 x 335 x 475mm (H x W x L).
protected, max, 7 3/4 x 13 3/16 x 18 5/8 in
voltage + 5V short Weight 12.5kg 27Alb net,
term
Trigger Output Format: One pulse per sequence Environment Operating temperature range 0 to
{rear panel) {PRBS} only. +55°С,
Position: Near the start of the Storage temperature range —40 to
longest zero block +75 C.
in PRBS.
Width: Nominally one clock Accessories hp 15508A:
Impedance: period. nominal to 75 ohms unblanced to 110 ohms
Р - round balanced impedance passive conver-
5 , ters having frequency range ! —1OMHz.
Amplitude: IV pk-pk min.
T En if Le + a +
ston... ess than Sns Notes All transition times relate to 10%
| 90% of puise height. All pulse widths
Overshoot: Less than 10% of pulse specified at 50% of pulse height
amplitude. ; -
Protection: Open/short circuit pro- OPTIONS
tected, max voltage |
+ SV short term E 001 All words replaced by 16 bit front
Clock Output Format: Detector clock avail- ne P ogramma dle wore e me can
, also provi Wo 1 words alter-
rear panel able as a monitor.
( Р Width: Nominal 50% dut nated by an external signal applied
cycle for ere via the rear panel. Changeover is
clock | synchronous with end of words. Zero
Impedance: 50 ohms nominal to add then operates on individual 8 bit
| words, and trigger output is 8 bits
ground. wide |
Amplitude: - in, но
Transition Leo oo 5 ns External input 250mV pk-pk
Times: ; sensitivity: squarewave DC to
Overshoot: Less than 10% of y e Ks
puise amplitude. trian lar Nave. o
Protection: Open/short circuit 5 ОН, 10 ОКНУ
tected . voi- —_
pro SC RAR. VO Max input vol- 15Y rms.
tage * SV short term. tage:
GENERAL ;
Impedance: nominally 1000
710% +10% ohms
Power Supply 115V or 2
—22% —18% 002 Siemens 1.6mm connectors replace
AC 48 — 66Hz max. | all external 75 ohmsBNC connectors.
consumption approx 110VA 003 Combination of options 001 and 0072.
Probe Power External fused supplies of nominally 099 Clock frequency offset generation
+5V, 200mA and-35V, 200mA for deleted,
HP logic probes (rear panel). 100 Internal clock frequencies of 2048,
Packaging Modified hp 1700'series oscilioscope 3448 mE at f3 = 34 368
case with fan, clip-on front cover Mb/s with a ternary coded output & in-
with space for power cable, accessor- put format, the following parameters
ies, and instruction manual. apply
Connectors All signal connectors are BNC (except Data Output Impedance: Nominal 750) to ground.
options 002, 003). Amplitude: tiv £O.EV.
Printer output via 50 pin Ampheno! Zero Level: OV Жо ту,
connector. Transition <ans.
Recorder output via two binding Times:
posts, Overshoot: < 10% pulse Amplitude.
1-6
Pata Input Rate: Nominal 34.368Mb/s.
Impedance: Nominal 7552 to ground.
Equalisation: Automatic YF equalisa-
tion for cable losses up
to -I2dBat ке, froma
1V pk source.
Format: Ternary coded HD B2 or
HDB3.
Amplitude: 3V pk max.
Indicator: LED illuminated if data
transitions present,
101 Internal clock frequencies of 1544,
6312 and 44736kHz HDB3/HDB2
codec replaced by B6ZS/B3ZS codec.
When the 3780A is used at £3 = 44,736
Mb/s with a ternary coded O/P & 1/P for-
mat, the following parameters apply.
Data Output Impedance: Nominally 7582 unbal-
anced,
Shape: Conforms with CCITT
pulse mask for co-axial
pair interface at 44.736
Mb fs (CCITT recom-
mendation G703.4).
Amplitude: Nominally 0.6Y pk.
Data Input Rate: Nominally 44.736Mb/s.
Impedance: Nominally 7 587 unbal-
anced.
Equalisation: Automatic JT equalisa-
tion for cable losses up
to 12dB at fc/, froma
0.909Y pk source.
Format: Ternary coded B6ZS or
B3ZS.
Amplitude: 3V pk max.
Indicator: LED liuminated if data
transmission present.
102 Internal clock frequencies of 1544,
6312 and 3152kH7 HDB3/#1DB2
codec replaced by BOZS/B3ZS
codec.
1-14. DEFINITION OF TERMS
1-15. The following are brief definitions of terms which
relate to the functions of the instrument and are common-
ly used in this manual:
1-16. AMI
Alternate Mark Inversion is a form of Ternary data {des-
cribed below) in which data “Marks”, normally represen-
ting “ones”, are alternately positive and negative going.
The advantages of this basic code are that the average de
potential on the line is zero, and that this code can be used
to detect if one data bit is missing as two consecutive bits
would then have the same polarity.
General Information
| ~ LL | O |-- DO wn} — | нее | — 1 EES l= | = Eo | = |
AMI DATA
TA mr чи]
Figure 1-3 AMI Data/Clock
1-17. BER
Bit Error Rate is the rate at which errors occur relative to
the clock count. If 10 errors occur in 1000 clock periods
the BER is 1.0 x 1072.
1-18. Binary Data
Data ones and zeros are represented by a two level signal.
See RZ and NRZ.
1-19. Bipolar Violations
Violations of the coding rules in which two consecutive
bits have the same polarity. The data bit which violates the
coding rules is normally designated V,
6 Jour Le een] — i
— Y mn. E 0— | os ] aj O = 1 au | wm Ü) m 8 — e
AMI DATA [| || 7
|| Y ELA TICA | |
Figure 1-4 Bipolar Violation
1-20. Codes
Refinements of the AMI code in which long sequences of
zeros are eliminated by substituting a fixed pattern for
the sequence of zeros. The substitution allows the clock
signal ‘to be more easily recovered from the data when
long runs of zeros occur. The codes referred to in this
manual are as follows:
HDE2/83ZS High Density Binary 2 (HDB2)/Binary 3 zeros
substitution (B3Z8) are two similar codes in which a pat-
tern is substituted for each block of three consecutive zeros
in the data stream.
1-7
Model 3780A
ore Tondo Qo fmm dom me Qo [om Gon foe on om 1]
AMI DATA Л | LAL
#
HD8 2 / 532$ DATA # #
SUBSTITUTED
PATTERN
Figure 1-5 HDB2 Data
HDB3 High Density Binary 3 substitution and
B6ZS Binary 6 Zeros substitution are codes with substi-
tutions for 4 and 6 consecutive Zeros respectively.
pe En |-— o — 4 — fo q [= 0 -- Per D joe [1 woe i ее E i = | —— | — 1— |
wow | | | LAL
HDB3 DATA J
SUBSTITUTEO
PATTERN
Figure 1-6 HDBS Data
SUBSTITUTED
PATTERN UT её
EOS
Figure 1-7 B6ZS Data
1-20A Violation of Violation HDB2/HDB3 only
t a Dee ene — E а : fmf] em ema Te fe |
en Г = fr
AMIE Len A me = nm rmac one
DATA В |
r PU _ ce
5 У :
GBA i Ed he ce _ | L i | PE ”
| ; ef 1 Le
He L. ham I
мо pros VECTATICIN 15 EA
1 + г i ad AS PRÉVICIOS VIOLATICA
HOA7 — on E осн roman pen Фе. - — Lo pie pe
! H it: Tig
E | Li LE Li iY
21
WHILATIGH 15 SAME
AL PREVIDIGGS VIOLAT HD
Po ET Lm [ I E mn 3 PT PTE FI O y PU | mi Pf
I 1 E La Las Li à LU Lei Led Ld LI LI LS EZ La | Led ds
ATH
Figure 1-8 AMI Data
1-8
Instruments fitted with S1 on the 03780-60134 Board have
an additional mode of operation. In the VOCAB position a
code error is recorded when a violation (two successive bits
of the same polarity} of the coding rule occurs. In the
VIOLS position, a code error is only recorded when there
are two successive violations of the same polarity.
With AMI code errors, any violation of the AMI coding rule
is recorded as code error, irrespective of the position of the
VOCAB/VIOLS switch,
1-21. Delay Data
As applied to this instrument delay data is data which is
delayed by 6 bifs less than a full sequence ie it is 6 bits
in advance of the normal data.
1-22. Error Add
Binary data bits changed to produce an error without in-
creasing the sequence length. The errors introduced take
the form of the complement of 10 data bits in each 1000
bits.
|= t= f= tom 0 0m
moro mo | LL TUL
WORD 1100 | | | | | | |
ERROR ADD Und о мене me
ja ADDED ERRORS — —
Figure 1-9 Error Add
1-23. NRZ
Non Return to Zero data remains at the ‘one’ level for the
whole clock period. The data level is continuous between
consecutive data ‘ones’.
= 0m|-0 | =i] |-0-
NRZ | | | | | |
BINARY DATA
me Oem [mg [oe pm Foo pom Fo gy | to fp
1780 A 1|-0-|-1—]--0-|--1-Ho-]-1--0-]-- 1] 0
BINARY DATA
cock [UU OE
Figure 1-10 NRZ Data
In theory NRZ data rising and trailing edges are in phase
with the clock edges, but the 3780A clock edges coincide
with the centre of the valid NRZ data.
1-24. Offset Clock Frequency Generation
The generation of clock frequencies which may be varied
about the normal fixed frequencies F1, F2 or F3. F1, F2
and F3 are the frequencies of the crystal oscillators in the
3780A.
1-25. Offset Clock Frequency Measurement
The measuremeni of the fractional frequency difference
between the normal and offset frequencies ie AF offset/
F normal where F normal is the frequency F1, F2 or F3
generated in the Pattern Generator section of the instru-
ment making the measurement,
1-26. PRBS
Pseudo Random Binary Sequence. A repetitive sequence
2.1 bits long generated by an n stage shift register. For
example a 9 stage shift register produces a sequence 2% 1
or 511 bits long.
1-27. Recovered Clock
The receiver clock signal recovered from data.
1-28. RZ
Return to Zero data is at the ‘One’ level for the duration
of the clock mark and returns to zero for the duration of
the clock space.
—— |-0—]—0—|<-1—]<1= |- tj 0] | |
BINARY DATA
Figure 1-11 RZ Data
1-29. Synchronisation
As used in the 3780A synchronisation is the generation in
the Error Detector of the particular sequence being re-
ceived. The sequence generated in the Error Detector
must be in phase with the received sequence for correct
synchronisation.
General Information
1-30. Ternary Data
“One” and “Zero” are represented by a three level signal.
Ternary data is a general term which includes AMI and the
codes described in this section.
1-31. Word
A repetitive fixed sequence.
1-32. Zero Add
Zeros added to each sequence which increase the sequence
length.
[mf mr fo Of ное
WORD 100 ADDED ZERQS
ZERO ADD 002 | | | | | |
cock J | || || || | | | || || || |
Figure 1-12 Zero Add
1-33. DESCRIPTION
1-34, The 3780A Pattern Generator-Error Detector is a
complete error measuring system contained in one portable
unit. The instrument measures Binary and Code errors on
digital transmission equipment operating at bit rates in the
range 1Kb/s — 50Mb/s. Frequency Offset measurements
can also be performed at the frequencies installed in the
generator.
1-35. Binary Errors. The pattern generator transmits a di-
gital test pattern into the system to be tested. Simultan-
eously, the error detector compares the output of the
system under test bit by bit with an internally generated
pattern. Detected errors can be counted over a chosen
gating period and displayed as bit error rate (BER) or
total error count (COUNT) on an LED display.
1-36. Code Errors. The error detector can. be used to
“monitor interface or line coded information for code
errors. These are detected during the decoding process
and are counted and displayed in the same way as binary
errors, The information need not be a pattern produced
by the generator.
1-9
Model 3780A
1-37, Frequency Offset. The clock frequency in the pattern
generator may be offset and measured in the error detector
(receiver). The offset is displayed as a fraction of the nomi-
nal crystal centre frequency. The offset of external clock
signals applied to the generator can be measured if the fre-
quency is within 25kHz of an installed crystal frequency,
1-38. Frequency Control. The generator and receiver may
be operated from external clocks in the range lkHz to
SOMHz. The generator has three internal crystal sources
in the range 1.5 — 50MHz which may be selected from a
number of options. The receiver clock can be recovered
from incoming patterns at the frequencies installed in the
generator. The generator internal clocks can be offset by
up to at least £50ppm {except Option 099),
1-39, Pattern Selection. Three maximal length pseudo ran-
dom binary sequences (PRBS) of length 511, 32767 and
1048575 bits and five four bit repetitive word patterns are
produced by the generator. The PRES generator may also
be used to generate random repetitive word patterns of
length 9, 15 or 20 bits.
1-40, Option 001 provides a front pane] programmable, 16
bit word in place of the five four-bit and random repetitive
word patterns, This can also provide two 8 bit words alter
nated by an external signal applied via the rear panel.
1-4}. Ор 10 999 zeros can be added once per sequence to
ali of the selectable patterns.
1-42. When the PRBS/WORD switch of the receiving instru-
ment is set to one of the PRES positions, or when the inter-
nal SYSTEMATIC ERROR DETECTION awitch A37 S21s
set to OFF, the error detector automatically recognises and
reproduces a synchronous error free version of any PRES
or WORD pattern produced by the generator. This includes
PRES but excildes any pattern containing added zeros or
alternating words (Options 001 or 003),
Instruments are supplied with the internal SYSTEMATIC
ERROR DETECTION switch, A37 $2, set to the ON posi-
tion. Ín this mode the reference WORD of the receiving in-
strument can be preset to one of the fixed 4 bit words, or
with Options 001 or 003 to the 16 bit word. This is achieved
by setting the PRBS/WORD switch of the receiving instru-
ment fo the appropriate 4 bit word, or with Options 00] or
003 by setting the PRBS/WORD switch to 16 and selecting
the appropriate word with the WORD SELECT switches,
Systematic errors on the 4 or 16 bit words will then result
in sync loss at the receiving mstrument,
A typical example of the use of systematic error detection
in an end-to-end measurement is given below:
If the transmitted word 1100 is repeatedly received as 1000
as the result of a systematic fault, then the following results
will be obtained with the receiving instrument.
PRES/WORD
witch Setting
{receiving instrument) RESULT
9, 15 or 20 NO ERRORS WORD
1000 NO ERRORS WORD
1100 ERRORS SYNC LOSS
An indication of receive pattern lock is given by LED
lamps. A manual override on the automatic syncis provided
which forces a sync loss; when released the instrument re-
verts to automatic synchronisation.
1-43, Data and Clock Format. The generator test pattern
may be produced in binary RZ or NRZ, or ternary, HDB3
or HDBEZ formats, When operating in binary format a
second binary output is available which is 6 bits advanced
on the main data output. The receiver data input format
selection is independent of the generator controls.
1.44. CLOCK or CLOCK may be selected independently
on generator cutput and receiver input.
1-45. A choice of trigger threshold is provided on clock and
data inputs allowing continuous or burst mode operation.
indication of signal triggering is given by LED lamps.
1-46, Error Counter Control and Display. Control of error
counter timebase may be internal over 10%, 10% or 10
clock periods, manual via start/stop push buttons or exfer-
nal via the printer ontpuf connector, Internal error counts
are displayed as a scaled BER reading in the form X.Y x
10 Error counts over a manually or externally con-
trolled timebase are displayed as a scaled COUNT reading
in the form X.Y x 107% Frequency offset js displayed as
a fraction of the nominal centre frequency in the form
XY x 107" where n = 6 usually. The display uses seven
segment LED characters.
1-47. Flags. Indications of measurement gating, sync loss
and count overflow are provided by LED lamps. An indi-
cation is also given if the last measurement result is based
on less than 100 errors.
1-48, Self Check (Error Add). A fixed binary error rate
of 10 * may be injected into the test pattern in order to
check the error detector functions, ERROR ADD and
ZERO ADD cannot be used simultaneously.
1-49. Trigger Outputs. A trigger output, giving one transi-
tion per sequence, is available from a front panel socket
on the generator. The output is modified during zero add
to allow examination of the zero block or the pattern
immediately following it on an oscilloscope.
1-50. The receiver section also provides a trigger output,
(for PRBS only) giving one pulse per sequence, from a rear
panel socket.
1-51. Error Detector Outputs. In addition to receiver trigger
and clock outputs, there are three outputs which can be
used to evaluate error distribution, These are an error
output giving one pulse per error, a BCD printer output
and a pen recorder output.
1-52. OPTIONS
1-53. Option 001 provides front panel programmable 16
bit or two 8 bit words as described in Section 3, Para. 3-15.
1-54. Option 002 provides small Siemens connectors on
all external 75 ohms interfaces in place of BNC connectors.
1-55. Option 003 is a combination of options 001 and 002,
1-56. Option 099 deletes frequency offset generation.
1-57. Options 100-102 provide different crystal freguencies
to those fitted in the standard instrument. The frequencies
available are listed in Table 1-2.
Table 1-2 Internal Crystal Clock Frequencies
STANDARD 2048, 8448 and 1536kHz
OPTION 100 2048, 8448 and 34368kHz
OPTION 101 1544, 6312 and 44736kHz
OPTION 102 1544, 6312 and 3152kriz
In the case of options 101 and 102 the HDB3/HDB? codec
is replaced by a B6ZS/B3ZS codec.
1-58. ACCESSORIES SUPPLIED
1-59. Figure 1-1 shows the HP model 37804 and the acces-
sories supplied, these are as follows: -
Operating Manual ............. (33780-90011
Operating and Service Manual ..... 03780-90008
PowerCable................. see paragraph 2-12
and Figure 2-2
Extender Board (fitted. ......... 03780-60021
behind board position
39 and fixed to the
instrument sideframe with
3 screws).
Storage Cover. ....... ES 03770-70096
Printer Output connector ........ 1251-0086
1-60. ACCESSORIES AVAILABLE
1-61. The following accessory is available for use with the
3780A and can be purchased through your nearest HP Sales
and Service Office (see list at rear of manual).
HP Model 15508A. , 7581 Unbalanced to
1100 Balanced
Converter with a
frequency range from
i to 1OMEZ,
1-62, RECOMMENDED TEST EQUIPMENT
1-63. Equipment required to maintain the model 3780A is
listed in Table 1-3. Other equipment may be substituted if
it meets or exceeds the criticai specifications listed in the
table. The section of the manual in which each item of test
equipment is given in the USE column where P = Perfor-
mance fests, A = Adjustments and T = Troubleshooting.
Table 1-3 Recommended Test Equipment
Instrument
Critical Specification
Recommended Model Use
Electronic Counter de — HOMH?2
<350ps.
The time base must use a high stability
crystal oscillator <5 x 1079 /day
<1 x 1071/1 sec rms {short term)
7 x 107° 0° to 50°C. Must be capable
of making ratio measurements as well
as frequency and period. The counter
must also have prescaler facilities up
to TOMHZ input frequencies.
Oscilloscope Sensitivity 5mV/cm dual trace. . hp 180A/1808A/18Z0A/21A PAT
10:1 Probe de — 75MHZz, impedance 1MC and hp 10048
5082.
Sampling
Oscilloscope Dual trace, de — 1GHZz rise time ho 1804/1810A | PAT
hp 5327 A OPO31 PAT
Model 3780A
Table 1-3 Recommended Test Equipment {continued}
Instrument Critical Specification Recommended Model Use
HF Probe de -- SGOMHz. hp T1204 PAT
10:1 Divider 1082 input impedance. ha 10241A PAT
BNC Adastor ho 1250-0052 PA
VEE Oscillator TOMH, BOMMz, O — +10dBm hp S654A PAT
into BOLL, with a variable output
control.
Test Oscillator TkHz — 10MbHz, 500mV pk-pk into hp 56516 Cotion 07 PAT
7582 or greater.
Function Generator 0.0001 Hz — iMt+iz sine and square ho 33104 Р
wave, with E EV de offset control,
Pulse Generator Rise times tess than 2ns. Min period пр SCOSA P
less than 20ns. Min pulse width less
than 8ns. Must be able to be exter.
naily triggered. Must have compie-
ment output control. Must give
1.6V gk-pk into 5087.
Digital Voltmeter 1mV Resolution and isolated input ho 34740A/34 7024 PAT
terminals.
Attenuator {Oty 1) de — SOMHz, Q — 2505 presettable, hp 3750A PA
7582,
Attenuator (Qty 2) 5012 2040B coaxial fixed rise time hp 8591B PA
<2 5n5.*
Power Supply D — 15V, 0.75A dual de power ho 62068 PAT
suppiy.
Resistor 3 off, 7582 1% 1/8W hp 0757-0598 PA
Resistor t off, 51182 1% 1/8W hp 0757-0416 PA
Resistor 1 off, 1,5K82 1% 1/8W hp 0757-0427 PA
Resistor t off, 10K82 1% 1/8W hp 0757-0442 P
Cables STD à off, 7512 BNC hp 15525A PAT
Cables STD 2 off, 5002 BNC hp 1G501A PAT
75/5087 Matching Pad 3 off, de — 200MHz hp 85478B PA
Hohde & Schwarz
type DAF
EN 18084 + Adantors
FHS 40001/5650 &
FED 40801/75
CGreenpar type
507.4713.707
Digital Recorder hp 50554 Р
VHF Oscillator hp 32004 A
Logic Puiser hp 10626T T
TTL Logic Probe hp 10525T T
ECL Logic Probe hp 10525€ T
*Note: When using 86814 20d8 coaxial attenuator (5681) Vo =
TEM pipi
General Information
Table 1-4 Recommended Adaptors for Standard Instrument
item
Minimum Specification
Recommended Type
Adaptor BNC female
58082 to GR 874 1 off
Adaptor N — Maie 5062
to BNC femaie 5082
Î aff
Adaptor BNC TT 7582
2 off
Adaptor BNC 'T’ 8082
2 off
Adaptor Banana to BNC
female
Adaptor ВМС Ма 755)
to BNC Mate 7582
758) Load BNC
5082 Load BNC
Greenpar GE 500/508
hp 1250-0082
Greenpar GE 375531
hp 1250-0781
пр 10111A
hp 1250-1288
hp 155224
hp 11583A
Table 1-5 Recommended Adaptors for Option 002 Instrument
Nate: - The adaptors listed here are in addition to the ones listed for the standard instru-
ment.
item
Minimum Specification
Recommended Type
Adaptor 1.6/5.6mm male
7507 to BNC female 750
3 off
Spinner BN 88 84
Installation
SECTION Hi
INSTALLATION
2-1. INTRODUCTION
2-2. This section provides installation instructions for the
Model 3780A and its accessories. This section also includes
information about initial inspection, damage claims, pre-
paration for use, packaging, storage and shipment.
2-3. INITIAL INSPECTION
2-4. Inspect the shipping container for damage, If the
shipping container or cushioning material is damaged, it
should be kept until the contents of the shipment have
been checked for completeness and the instrument has
been checked mechanically and electrically. The contents
of the shipment should be as shown in Figure 1-1 and
listed in Paragraph 1-59, Procedures for checking the
electrical operation are given in Section IV of this manual.
If the contents are incomplete, if there is mechanical dam-
age or defect, or if the instrument performance fails to
meet specification, notify the nearest Hewlett-Packard
Sales and Service Office as listed at the rear of this manual.
If the shipping container is damaged, or the cushioning
material shows signs of stress, notify the carrier as well
as the Hewlett-Packard Office. Keep the shipping mater-
ials for the carriers inspection. The Hewlett-Packard Office
will arrange for repair or replacement at HP option with-
out waiting for a claim settlement.
2-6. PREPARATION FOR USE
2-6. Power Requirements
2-7, The model 3780A requires a power source of 115V ac
(+10% to —22%) or 230V ac (+10% to —18%), 48 to 66Hz
single phase. The maximum power consumption is approxi-
mateiy ОМА.
WARNING
If the instrument is energised via an
autotransformer, ensure that the com-
mon terminal is connected to the
earthed pole of the power source.
2-8. Line Voltage Selection
CAUTION
BEFORE SWITCHING ON THIS INSTRU-
MENT ensure that the voltage selector is set
to the voltage of the power source,
2-9. The location of the power input connector, power line
fuse and voltage selector switch are shown in Figure 2-1.
Remove the power line fuse. Set the voltage selector
switch to 115V or 230V as appropriate. Ensure that the
correct fuse is fitted for the voltage selected as given in
Table 2-1. Replace the fuse,
CAUTION
The replacement of blown fuses should not be
performed without reference to the power
supply troubleshooting procedure Page 8-55.
Power supply assembly damage can occur if
the correct procedure is not carried out.
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VOLTAGE
SELECTOR SWITCH
—
POWER INPUT
CONNECTOR
LINE FUSE
Figure 2-1 Power Input, Fuse and Voltage Selector
2-10. Fuses
2-11. The power line fuse depends on the supply voltage
selected. Table 2-1 provides the ratings and Hewlett
Packard stock numbers of suitable fuses.
Table 2-1 Fuse Ratings
Voltage Selector Fuse Rating HP Stock Number
115v ЗА Timed 250V 2110-0381
2304 1.54 Timed 250V 2110-0304
2-12. Power Cable
2-13, In accordance with international safety standards this
instrument is equipped with a three wire power cable. When
connected to an appropriate power receptacie, this cable
grounds the instrument cabinet. The type of power cable
shipped with each instrument depends on the country
of destination. Figure 2-2 illustrates the standard power
receptacles that are commonly used, The HP stock number
Model 3780A
CABLE STOCK NUMBER 8120-2104 8120-0695
8120—1692 8120-1703 8120—1521
Figure 2-2 Power Receptacles
shown with each receptacle is the stock number of a power
cable equipped with the appropriate mating plug for that
receptacle. If the appropriate power cable is not included
with the instrument, notify the nearest hp Sales and Service
Office and a replacement will be provided.
2-14, The colour codes used in each power cable are:
Table 2-2 Power Cable Colour Codes
Line Brown
Neutral tite
Ground Green/ Yellow
WARNING
BEFORE SWITCHING ON THIS IN-
STRUMENT, the protective earth ter-
minal of this instrument must be connec-
ted to the protective conductor of the
{mains} power cable. The mains plug
shall only be inserted in a socket outlet
provided with a protective earth con-
tact. The protective action must not be
negated by the use of an extension
power cable without a protective con-
ductor (grounding).
2-15. STORAGE AND SHIPMENT
2-16, Temperature Hange
2-17. The instrument may be stored or shipped in temper-
atures within the limits —40°C to +75°C. It is advisable to
protect the instrument from extreme temperature variation
which can cause excessive condensation.
2-2
2-18. Packaging
2-19. Original Packaging. Containers and materials identical
to those used in factory packaging are available through
Hewlett-Packard Offices. If the instrument 1s being re-
turned to Hewlett-Packard for servicing, attach a tag in-
dicating the type of service required, return address, model
number and full serial number. Mark the containers
FRAGILE to ensure careful handiing. In any correspond-
ence, refer to the instrument by model number and full
serial number.
2-20. Other Packaging. The following general instructions
should be used for repacking with comercialiy available
materials:
(a) Wrap the instrument in heavy paper or plastic.
If shipping to Hewlett-Packard for servicing, attach
a tag indicating the fype of service required, return
address, model number and full serial number.
(b) Use a strong shipping container eg. a doubie
walied carton of 350 pound tested material.
(c) Protect the control panel with cardboard and
insert a three to four inch layer of shock absorbing
material between all surfaces of the instrument and
the sides of the container.
(d) Seal the shipping container securely.
(e) Mark the shipping container FRAGILE to
ensure careful handiing.
(1) In any correspondence, refer to the instrument
by model number and full serial number.
Installation
2-21. Mating Connectors 2-23. interconnecting Cables
2-22. The connectors which mate with the front and rear 2-24. A selection of 50 and 75 ohm interconnecting cables
panel BNC connectors vary depending on the diameter of are available from Hewlett-Packard Sales and Service
the cable used. Some examples of suitable connectors are Offices. A cable, stock number 562A-16C, suitable for
given in Table 2-2. connecting the model 3780A printer output to an hp model
SOSSA, 5050B, or 5150A printer is also available.
Table 2-3 Mating Connectors
Front/Rear impedance/ Cable Mating
Panel Type Typical HP Stock Connector
Connector 0/0 Number HP Stock Number
Inches
GENERATOR:
Clock 1/P
Clock OFF
Data O/P 7582 BNC 0.269 8120-1289 1250-1448
0.153 8120-0049 1250-0629
Delay Data O/P
RECEIVER-
Clock 1/7
Data (/P
GENFRATOR:
Trigger O/P
RECEIVER:
Rear Panel: 50072 BNC 0.199 8120-0017 1250-0533
Clock OFF
Error O/P
Rac Trig O/P
PRINTER O/P 50 Pin Amphenol For cable with connectors 1251-0086
see paragraph 2-23. Amphenol
Type
57-30500-375
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(11)
The data is not modified and the sequence is de-
termined by controls (7) (8) and (9) only. In the
EREOR ADD position a fixed binary error rate
of 107* is introduced into the generator sequence
by producing 10 consecutive errors in every 1000
ciock periods,
The ZEROS switch selects the number of zeros
added to any pattern when the ZERO ADD posi-
tion of the ZERO ADD/NORM/ERROR ADD
switch (10) is selected.
3-8. GENERATOR FORMAT CONTROLS AND
CUTPUT CONNECTORS
Determine generator output format.
(12)
613)
(14)
(15)
(16)
(17)
The DATA FORMAT switch selects between bin-
ary and ternary data output formats. The binary
data formats, RZ, return to zero, and NRZ, non
return to zero are available at both DATA O/P
(14) and DELAY DATA. O/P (15) connectors.
The ternary data formats, AMI, alternate mark
inversion, and CODE, HDR3 or HDB2 (options
101 and 102 B6ZS or B3ZS), selected with the
rear panel CODE switch are available at the DATA
O/P connector (14) only.
The CODE switch on the rear panel selects HDB3
or HDB? code formats (options 101 and 102
BOZS or B3ZS) when the CODE position of the
DATA FORMAT switch (17) is selected,
The DATA OP connector provides a 75 ohm un-
balanced data output as selected with the PAT-
TERN and FORMAT controls. The output ampit-
tude of the mark in binary formats is 3V and in
ternary formats +2.37V, The space in both for-
mats is OV. The connector has open and short
circuit protection and will withstand an input of
up to +6V for short periods.
The DELAY DATA OP connector provides a data
output of the binary formats RZ and NRZ, de-
layed by 6 bits less than a complete sequence ie 6
bits advanced on the data at DATA O/P (14). In
ail other respects this output is identical to the
normal data output.
The CLOCK/CLOCK switch selects normal or in-
verted generator clock output at the CLOCK O/P
connector (17),
The CLOCK O/P connector provides a 75 ohm un-
balanced generator clock output. The output can
be normal or inverted as selected with the
CLOCK/CLOCK switch (16) and the output fre-
quency may be either an internal or externai
clock source. The output mark amplitude is 3V
(18)
Operation
and the space is OV. The connector has both open
and short circuit protection and will withstand an
input of up to £6V for short periods.
The TRIGGER O/P connector provides one tran-
sition per word or seguence coincident with the
start of the word and before the longest block of
zeros of a PRES, The amplitude of the trigger
output is IV and it is a 50 ohm unbalanced sig»
nal. The output has both open and short circuit
protection and will withstand an input of up to
+5 V for short periods.
3-9, RECEIVER INPUT CONTROLS AND
CONNECTORS
Set receiver clock and data input conditions.
(19)
(20)
(21)
(22)
(23)
The DATA I/P connector is a 75 ohm unbalanced
input which accepts the data input for the re-
ceiver. The data input frequency range is 1Kb/s
to SOMb/s and the input sensitivity is 0.5V pk-pk.
The maximum input amplitude is 5V pk-pk within
the limits 45V, The data triggering threshold can
be selected with the DATA THRESHOLD switch
(21).
The DATA FORMAT switch selects the approp-
riate binary or ternary receiver operation for in-
coming data at the DATA I/P connector (19). In
the code position a choice of HDB3 or HDB? code
(options 101 and 102 B6ZS or B3IZS cade) is pro-
vided with the rear panel CODE switch € 13) which
is common with the generator.
The DATA THRESHOLD switch selects the re-
ceiver data triggering level. Trigger level should be
chosen to fall within 10% and 90% of data ampii-
tude. Binary triggering levels of GND (ground),
200mV or 600mV may be selected. Ternary
triggering levels of + 200mV or + 600mY may be
selected.
Note: In the recovered clock mode, threshold
level should be set closest to 50% of maxi-
mum input date amplitude to allow the
rising edge of the clock, after a fixed delay,
to coincide with the centre of the data
pulse,
The DATA INPUT TRIGGER indicator lamp is
‘on’ when data applied to the DATA I/P connec-
tor {19) is correctly triggered. The lamp will be
‘off’ if data transitions are absent for more than
150mS.
The CLOCK switch selects the receiver clock
source. In the EXT and EXT positions the receiver
is clocked with a normal or inverted input applied
to the RECEIVER CLOCK I/P connector (24). in
Model 3780A
the RECOVERED position the receiver is clocked
— with a signal recovered from the data at the DATA
—1/P connector (19). The appropriate clock re-
covery frequency is selected with the FRE-
QUENCY switch (2). — |
(24) The CLOCK I/P connector is an unbalanced 75
ohm input for a receiver external clock in the fre-
"quency range lkHz to 50MHz. The input sensi-
tivity is 0.5V pk-pk and the maximum input am-
plitude is 5V pk-pk within the limits £5V. The
clock triggering threshold can either be ground or
automatic [mean level of clock input ag selected
with the CLOCK THRESHOLD switch (5)]. The
CLOCK THRESHOLD switch is common with
the generator.
(25) The RECEIVER CLOCK INPUT TRIGGER indi-
cator lamp is ‘on’ when a clock signal appiied to
the CLOCK 1/P connector (24) is correctly
trigeered. The lamp will be “off” if clock transi-
tions are absent for 130 ms. |
3-10. SYNC AND SYNC INDICATORS
Automatic synchronisation with manual override and re-
ceived pattern indication.
(26) The RESYNC switch is a manual override on the
automatic synchronisation system. When the RE-
SYNC switch 1s pressed a search for synchronism
is initiated. The incoming pattern is examined for
parity with each of the possible incoming patferns
until less than 4 errors occur in 100 clock periods,
Synchronisation is then regained, and the type
of pattern indicated by one of the synchronisation
indicators (27) to (30),
(27) PRBS The normal 2%.-1, 215-1 or 2%..1 bit
PRES produced by the generator.
(28) PRBS The inverse of the 271, 23 or
2% _1 bit PRBS produced by the genera-
tor.
(29) WORD Any word which is repetitive in blocks of
9, 12, 15, 16 or 20 bits and ail zeros (any
word sequence with less than 4 ones in
100 clock periods). |
(30) AIS ALARM INDICATION SIGNAL, being all
ones {any word seguence with less than 4
zeros in 100 clock periods).
3-11. MEASUREMENT CONTROLS
Select, measurements to be made, display format, and time-
base.
3-4
(31) The MEASUREMENT switch selects the measure-
ment to he performed.
In the FREQUENCY OFFSET (AUT) position the
fractional difference between (Be standard and off-
set frequencies of rhe generator section 15 mea-
sured. With the CLOCK SELECTION switch (1)
set to OFFSET. the fractional frequency differ-
ence measured is the offset selected with the
OFFSET Af control (3) divided by the frequency
f selected with the FREQUENCY switch (3).
In the CONE ERRORS position the receiver moni-
tors the input data at DATA HP 19) for violations
of the coding laws, The coding law 15 selected with
the receiver DATA FORMAT switch (20) as either
AMI or CODE and in the CODE position the type
of code HDR3, HDH2 (option 101 and 102
B6Z5. BAYER) ix selected with the rear panel CODE
switch (133 which is common with the generator.
The result may either be displayed as a bit error
rate or error coun! as selected with the TIME-
BASE switch (373 The measurement range is
0.0 x 107 to 99 x 107“ in BER 10,00 x
10* to 9.9 x 10% in COUNT.
As an alternative to violations of the coding laws,
it is possible, with HDB2/HDB3 to measure viola-
tions of violations where an error is registered for
each violation which has the same polarity as the
previous volation. An internal switch A348],
selects between measurements of the coding law
errors (VOCAB) and measurements of violations
of violations CY IOLS). |
In the BINARY ERRORS position the receiver
measures the binary errors on 4 binary or a coded
input applied to the DATA I/P connector (19).
The binary errors are measured on a bit by bit
basis using a reference pattern generated in the re-
ceiver. The result may either be displayed as a bit
error rate or error count as selected with the
TIMEBASE switch (32), The measurement range is
0.0 x 1077 to 4.0 x 107? in BER and 0.0 x 101
to 9.9 x 10° in COUNT.
If the test signal being received is one of the fixed
4 bit words, or with options 001 or 003 a 16 bit
word, two methods of operation are available de-
pending on the setting of the PRBS/WORD switch -
(7). With the PRBS/WORD switch set to 9, 15 or
20, the receiving instrument will synchronise to
the incoming paittem irrespective of systematic
errors. With the PRES/WORD switch set to the
relevant word, the error detector will only synch-
ronise to that word,
The TIMEBASE switch selects the counter time-
base interval over which errors are counted. The
BER positions give a choice of 10%, 10% or 101°
clock periods for measurement gating. The
(33)
(34)
measurement result is automatically scaled and
presented in Ihe form X.Y x 10 * with an indi-
cation 1f this result is computed from less than
100 errors (39). In the COUNT position errors
are counted over a period either selected manuaily
with the START and STOP switches (33) and (34)
or externally by a command from an external
printer. In this mode a positive going TTL puise ai
pin 47 of the PRINTER OUTPUT connector (40)
stops the counter and produces a print command.
The counter normally restarts 400ms after the
stop command however it is possible, with the
change of an internal link, to hold the restart
until the pulse at PRINTER OUTPUT pin 47
goes negative.
The START switch controls the start of the
manual measurement gating period when the
TIMEBASE switch (32) is in the COUNT MAN
position. The count is initiated by the switch
being depressed. This switch can also be used
to restart a measurement when counting errors
over 10°, 10% or 10% clock periods.
The STOP switch stops the measurement when
counting over a manually controlled timebase,
The count is stopped by the switch being de-
pressed,
3-12. DISPLAY AND FLAG INDICATORS
Present the result and indicate state of measurement.
(357
(36)
(37)
The DISPLAY shows the measurement result.
Frequency offset measurements are displayed in
the form XY x 107. Code error and binary error
measurements arè displayed as BER in the form
XY x 10” or as COUNT in the form X.Y x
10,
The GATING flag indicates that a measurement is
in progress, The indicator will be “off” for at least
500ms between measurements.
The SYNC LOSS flag indicates loss of receiver
pattern synchronisation. The indicator is inhibited
during code error and frequency offset measure-
ment.
Sync loss will also be indicated when the PRES/
WORD switch (7) is in one of the fixed 4 bit word
positions which is different to the word being re-
ceived. With options 001 and 003 sync loss will be
indicated when the PRBS/WORD switch is set to
16 and the word selected with the WORD SELECT
switches is different to the word being received.
Operation
Note: This does not apply if the PRBS/ WORD
switch is set to one of the PRBS positions,
9,15 or 20 orif the internal SYSTEMATIC
ERROR DETECTION switch A3782 Is set
to OFF, gs the error detector will then syn-
chronise to any repetitive 9, 12, 15, 16 or
20 bit word.
(38) The OVERFLOW flag indicates that the internal
(39)
error or frequency count has reached or exceeded
9
107.
The <100 ERRORS flag indicates that less than
100 errors were counted during the last error
measurement. The indicator is inhibited during fre-
quency offset measurements.
3.13. RECEIVER OUTPUTS
(40)
(41)
(42)
(43)
The PRINTER OUTPUT connector provides an
8421 BCD output of the measurement result and
current flag signal. In the BER and COUNT MAN
positions of the TIMEBASE switch (32) the print
command is at the termination of the measure-
ment and in the COUNT EXT position the print
command is initiated by the printer providing a
positive going TTL pulse at pin 47 of this connec-
tor, Further details of the printer output are given
on page 3—13.
The RECORDER OUTPUT connectors provide a
high impedance current source output suitable for
connection to a chart recorder. The output com-
prises 16 current levels with a total variation of
1m A into an impedance of 10K ohms max. There
is an eleven level indication of BER and a four
level indication of count and the response time is
500ms minimum, Further details of the recorder
output are given on page 3-13.
The RECORDER CALIBRATION switches pro-
vide ImA for FULL SCALE and ÔmA for ZERO
calibration of a chart recorder connected to the
RECORDER OUTPUT connectors (41).
The RECEIVER CLOCK output provides an out-
put of the receiver clock signal for recovered or
ext clock. The output amplitude is 1V min pk-pk
and the pulse width is nominally the same as the
clock with a 50% duty cycle for recovered clock.
The connector has both open and short circuit
protection and will withstand an input of up to
+5V for short periods. The cutput impedance is
50 ohms. |
3-5
Model 3780A
(44)
(45)
The ERROR output connector provides one
pulse per error. The output pulse amplitude is
1V min pk-pk and the pulse width is nominally
the same as the clock mark. The connector has
both open and short circuit protection and will
withstand an input of up to £5V for short periods,
The impedance of this output is 50 ohms and the
output is inhibited during sync loss.
The RECEIVER TRIGGER output provides one
puise per received PRBS sequence near the start
of the longest zero block. The output pulse am-
plitude is IV min pk-pk and the pulse width is
nominally one clock period. The connector has
both open and short circuit protection and will
withstand an input of up to £5V for short periods.
The ouiput impedance is 50 ohms.
3-14. POWER CONTROLS AND CONNECTORS
(46) The POWER INPUT module comprises a supply
voltage selection switch, the supply fuse and a
socket for the power supply cable, Details of set-
ting the supply voltage switch and fuse selection
are given on page 2-1 Paragraph 2—8,
WARNING
Before connecting the instrument to the
supply ensure that the voltage selector
is in the correct position and that a
fuse of the correct rating is fitted.
(47)
(48)
The POWER switch controls the ac power input
to the instrument.
The LOGIC PROBE SUPPLY connectors provide
power for a logic probe which may be required for
the service or repair of the instrument. Both + and
—3 volts are available and both supplies are inter-
nally fused at 200mA.
3-15. OPTION CONTROLS AND CONNECTORS
Option 001/003
Option 001 is the 16 bit word option and option 003 is the
16 bit word option with small Siemens connectors.
(49)
3-6
The PATTERN SELECTION switch selects the
pattern to be generated, In the n = 9, 15 and 20
positions a maximal length PRBS of 281 is pro-
duced as for the standard instrument. In the
n = 16 position the generator produces a repetitive
16 bit word whose content is selected with the
WORD SELECT switches (51). In the ALT posi-
tion the generator produces two 8 bit repetitive
words A and B alternated by an external signal
applied to the GEN ALT WORD 1/P connector
(50) on the rear panel. The word ‘A’ is selected
by a positive going transition of the input signal
and the word *B” hy a negative going transition,
(30) The GEN ALT WORD 1/P connector accepts a
signal to switch between words A and Bas selec-
ted with the WORD SELECT switches (513. The
input sensitivity is 250mY pk-pk for a de to
IGOkHz square wave or O.5Y for a 200Hz to
100k Hz sine or triangular wave, The input imped-
ance is nominally 1K ohm and the maximum vol-
tage 15 15 V rms.
(51) The WORD SELECT switches select the content
. of the 16 bit or two 8 bit words produced by the
generator.
(10)/(52) The ZERO ADD/NORM/ERROR ADD
switch performs the same function as in the
standard instrument as described on page
3—2. Zeros are added once per sequence to
the 16 bit word between words or indivi-
dually fo the 8 bit words,
(18)/(53) The TRIGGER output socket provides a
| trigger output of one transition per word or
sequence as for the standard instrument des-
cribed on page 3-3. With the 16 bit word
the fransition occurs before each word and
in the alternate mode the transition occurs
before each € bit word A or B.
All other conirels, connectors and indica-
tors are the same as the standard instru-
ment,
Option 002
Option 002 instruments have small Siemens connectors in
place of the 75 ohm BNC connectors.
All other controls, connectors and indicators are the same
as in the standard instrument.
Option 100
(2)/(54) The internal crystal frequencies selected
with the FREQUENCY switch are as
follows:
fl 2,048kHz fy 8448kHz fa 34 308kHz,
These frequencies are listed on the rear panel
of the instrument,
All other controls, connectors and indicators
are the same as in the standard instrument.
Option 101
(2)/(54) The internal crystal frequencies selected
with the FREQUENCY switch are as
foliows:
fy 1,554kHz fy 6,312kHz 1 44,736kHz
These frequencies are listed on the rear panel
of the instrument.
When the 3780A is used at f, = 44.736Mb/s
with a ternary coded O/P and yr 1ormart,
the shape of an isolated data O/P puise con-
forms to a CCITT pulse mask (CCITT re-
commendation CG703.4). An equaliser (opera-
fional when f, and ternary coded data is
selected), incorporated at the data I/P port,
automatically compensates for interstation
cable losses up to 12dB at fe/, (fc = 44,736
Mb/s} from a 0.909Y pk source,
(133/(55) The rear panel CODE switch selects B3ZS
and B&ZS code formats in the generator and
receiver.
All other controls, connectors and indicators
are the same as in the standard instrument,
Option 102
(2)/(54) The internal cyrstal frequencies selected
with the FREQUENCY switch are as
follows:
fy 1,554kHz fy 6,312kHz fs 3,152k}Hz
These frequencies are listed on the rear panel
of the instrument.
(13)/(55) The rear panel CODE switch selects B3ZS
and B6ZS code formats in the generator and
receiver.
All other controls, connectors and indica-
tors are the same as in the standard instru-
ment.
Option 099
{1}/(3) The frequency OFFSET (Af) control and the
OFFSET position of the clock selection
switch are deleted.
All other controls, connectors and indics-
tors are the same as in the standard instru-
ment.
3-16. OPERATORS CHECK
3-17. The Operators checks allow the operator to check the
main functions of the instrument prior to use. A complete
specification check is given in Section IV Performance
Tests. The Operators Checks may be performed individuaily
or in any order. The control resetting information at the
Operation
end of each check applies to the checks when they are per-
formed in the order given.
3-18. Equipment Required
3-19, Details of the equipment required for the Operators
Checks are given in Table 1-3 Pagel-10. A summary of this
equipment is given below:
(a) Signal Generator SOMHz recommended type hp
8654A.
(b) Matching Pad 50/7582
(c) Three 750 cables, two of which should be of the
same length and construction ie they should have the
same delay.
3-20. The Signal Generator and matching pad are used to
check the external clock input and to reduce the time
taken for the BER, Count and Display Checks, Hf is poss-
ible to perform the BER, Count and Display checks using
the internal clock, the measurement time however will
depend on the frequency used, The BER 1019 check on
Pape 3-11 which takes 3 minutes 20 seconds at SOMHZ will
take more than 26 minutes at 631 2% Hz,
3-21. Preparation for the Operators Check
3-22. Before proceeding with the operators checks:
(a) Make a note of the option number of the instru-
ment as given on the rear panel.
(b) Using two 7582 cables of the same length and
similar construction connect the GENERATOR
CLOCK O/P to the RECEIVER CLOCK I/P and the
GENERATOR DATA O/P to the RECEIVER DATA
i/P. :
(c) Open Page 4-1 so that Figure 4-1 can be used
for reference while performing the Operators Checks.
Note: In some of the following checks the instrument will
loose synchronisation during the setting up pro-
cedure and the SYNC LOSS lamp will come on.
Unless otherwise stated the check relates to the
condition after svnchronisation has been regained,
3-23. CHECK PROCEDURES
3-24. Frequency and Offset Checks
Set all controls to the reference settings given on Page 4-1
and perform the procedure given in Table 3-2
3-7
Model 3780A
Table 3-2 Frequency and Offset Check Procedure
Procedure Check
Switch the POWER ON, RECEIVER CLOCK 1/P lamp on.
RECEIVER DATA 1/P lamp on.
PRBS lamp on.
<100 ERRORS tamp on.
DISPLAY 0.0 x 107°
GATING lamp FLASHING
Set the 11/12/13 switch to 2. GATING lamp FLASHING
Set the F 1/12/13 switch to 15. GATING lamp FLASHING
Set the OFFSET/NORM/EXT switch \ The displayed offset increases from
to OFFSET, 0.0x 10 when the OFFSET
Set the RECEIVER MEASUREMENT (AF) control is varied in either
switch to FREQ OFFSET (2/5). direction from its mid position.
Set the 11/12/13 switch to f2. The displayed offset increases
from 0.0 x 107% when the OFF-
SET (Af control is varied in either
direction from its mid position.
Set the f1/f2/13 switch to #1, The displayed offset increases from
0.0x 107 when the OFFSET
(Af) contro! is varied in either direc-
tion from its mid position,
To reset the controls to the reference settings as required for the Pattern and
Synchronisation checks:
Set the OFFSET/NORM/EXT switch to NORM and the RECEIVER
MEASUREMENT switch to BINARY ERROR.
3-25, Pattern and Synchronisation Checks Instruments without options 001 or 003 perform the pro-
cedures given in Table 3-3. Instruments with options 001
Set all controls to the reference settings given on page 4-1. or 003 perform the procedure given in Table 3-4,
Table 3-3 Pattern and Synchronisation Check Procedure
(Instruments without options 001 or 003).
Procedure Check
Set the WORD/PRBS switch to 15, SYNC LOSS lamp on briefly.
PRBS iamp ON,
Set the WORD/PRBS switch to 20. SYNC LOSS lamp on brisfiy.
PRES lamp ON.
Set the 2" —1/n switch to n. WORD lamp ON.
Set me WORD/PRES switch to 15. SYNC LOSS lamp on briefly.
WORD lamp ON,
Press and hold the RUN pushbutton,
Release the RUN pushbutton. WORD lamp ON.
Operation
Table 3-3 Pattern and Synchronisation Check Procedure
(Instruments without options 001 or 003) (continued)
Procedure Check
Press and hold the RESYNC pushbutton, SYNC LOSS tamp ОМ.
Set the WORD/PRBS switch to 0000. WORD lamp ON.
Set the WORD/PRBS switch to 1000. WORD lamp ON,
Set the WORD/PRBS switch to 1111. ALS lamp ON,
To reset the controls to the reference settings as required for the Format
Checks: я
Set rhe WORD/PRES switch to 9 and set the 21..1/n switch to 271.
Table 3-4 Pattern and Synchronisation Check Procedure
{Instruments with options 001 or 003).
Procedure
Check
Set the PRBS/WORD switch to 20.
Set the PRES/WORD switch to 15.
Set the PRBS/WORD switch toa 9.
Press and hold the RESYNC pushbutton.
Release the RESYNC pushbutton.
Set the PRBS/WORD switch to 16.
Set the WORD SELECT switches as toliows:
A 10000000
B 00000000
Set the WORD SELECT switches as follows:
À 14141411
В 1111170
Set the WORD SELECT switches as follows:
À T1111411
8 T1111111
SYNC LOSS lamp on briefly.
PRES !атр ОМ.
SYNC LOSS lamp on briefly,
PRES lamp ON.
SYNC LOSS lamp on briefly.
PRES lamp ON.
SYNC LOSS lamp ON.
PRES lamp ONL
WORD lamp ON,
WORD lamp ON.
WORD lamp on at each stage of
switching.
AIS lamp ON,
To reset the controls to the reference settings as required for the Format
Checks:
Set the PRBS/WORD switch to 9 and set all WORD SELECT switches to 0.
3-26. Format Checks
Set all controls up to the reference settings given on page 4-1
and perform procedures given in Table 3-3.
3-9
Model 3780A
3-10
Table 3-5 Format Check Procedure
Procedure
Check
Set the ZERO ADD/NORM/ERBOR ADD
Switch to ERROR ADD.
Set the CLOCK/CLOCK switch to CLOCK,
Set the RECEIVER CLOCK switch to EXT.
Reset the CLOCK/CLOCK switch to CLOCK. §
Disconnect the cable between the GENERA. |
TOR CLOCK 0/7 and the RECEIVER
CLOCK HP.
set the RECEIVER CLOCK switch to RE-
COVERED.
Add an extra 4 £%ft (1,2912 10.15m) to x
the cable from the GENERATOR CLOCK
O/P and reconnect to the RECEIVER
CLOCK I/P.
Reset the RECEIVER CLOCK; switch to
EXT,
Set the WORD/PRBS switch to 1111
{options 801 and 003 to 16 with the WORD
SELECT switches at 1111000000111100).— $
Set the ZERO ADD/NORM/ERROR ADD
Switch to ZERO ADD.
Set the ZEROS switch to 006
{options 001 and 003 set the zeros switch to
004}.
Set the RECEIVER INPUT FORMAT switch
to AMI,
Set the RECEIVER MEASUREMENT switch
to CODE ERROR, A
Set the OUTPUT FORMAT switch to AMI.
Set the RECEIVER INPUT FORMAT switch
to CODE.
Set the OUTPUT FORMAT switch to
CODE.
Reset the OUTPUT FORMAT switch to AMI.
Set the rear panel CODE switch to HDB7
{options 101 and 102, B375SI).
Set the OUTPUT FORMAT switch to CODE.
Reset the rear panel CODE,
Switch to HDB3 {options 101, and 102,
B6ZS}.
Reset the RECEIVER INPUT FORMAT
switch to AM.
Reset the OUTPUT FORMAT switch to RZ.
Set the ZEROS switch to 996 {options 001
and G03 set the ZEROS switch to 984 with the
WORD SELECT switches at 11110000
00900000}
DISPLAY 1.0х 107?
AJ ONES ZEROS lamp ON
PRES lamp ON
PRBS lamp ON.
DISPLAY 4.0 x 107!
DISPLAY 0.0 x 107°
DISPLAY 3.0 x 107! (HDB3)
options 101 and 102 1.0 x
107! (B6ZS)
DISPLAY 0.0 x 1075
DISPLAY 4.0 x 1077!
{HDB?7 and B37S}
DISPLAY 0.0 x 107°
DISPLAY 4.0 x 107!
DISPLAY 4.0 x 107°
Continued on Page 3-11,
Operation
Table 3-5 Format Check Procedure (continued)
Procedure
Check
Disconnect the cable from the GENERATOR DISPLAY 4.0 x 1075
DATA O/F and connect the GENERATOR
DELAYED DATA O/F to the RECEIVER
DATA 1/P.
To reset the controls as required for the COUNT, BER and Display, Checks:
Disconnect the cable from the GENERATOR DELAYED DATA O/P and
connect the GENERATOR DATA O/P to the RECEIVER DATA I/P.
Set the WORD/PRES switch to 1000 (options 001 and 003 to 16 with the
WORD SELECT switches at 10000000 00000000).
3-27. Count, BER and Display Checks
set ali controls
to
the reference settings given on
Page 4-1 with the following exceptions:
Set the WORD/PRES switch to 1000 (options 001 and
003 to 16 with the WORD SELECT switches at 1000 0000
0009 0000).
Set the ZERO ADD/NORM/ERROR ADD switch to ZERO
ADD,
Set the ZERO switch to 996 (options 001 and 003 to 984).
Set the RECEIVER INPUT FORMAT switch to AML
Set the RECEIVER MEASUREMENT switch to CODE
ERROR.
Perform the procedure given in Table 3-6.
Table 3-6 Count, BER and Display Check Procedure
Procedure
Check
Set the RECEIVER BER/COUNT
Switch to COUNT MAN,
Press the STOP pushbutton.
Sat the WORD/PRBS switch to 1111
{options 001 and 003 to 18 with ail
WORD SELECT switches at 1).
Sel the ZERO ADO/NORM/ERROR ADO
switch to NORM.
Set the OFFSET/NORM/EXT switch to
EXT.
With the generator-receiver clock and data
cables still connected, connect the BOD4A 7
signal Generator, set to 50M +17, to the
GENERATOR CLOCK 1/P via a 50/7502
matching pad, if a Signal Generator is
not available see paragraph 3-20,
Set the Signal Generator to produce à
500mY peak-to-peak signal at the GEN.
ERATOR CLOCK I/P,
Press the START pushbutton.
Display counting up.
The count is held and displayed.
GENERATOR CLOCK 1/P тр ON,
The count increases to 9.9 x 10%.
The display blanks with the GATING
lamp OFF and the OVERFLOW
ramo CAN,
NOTE, measurement time 20
seconds,
Continued on Page 3-12
Model 3780A
Table 3-6 Count, BER and Display Check Procedure (continued)
Procedure
Check
Set the RECEIVER BER/COUNT
switch to BER 10%,
Set the RECEIVER BER/COUNT switch
to BER 10%
Set the RECEIVER BER/COUNT switch
to BER 19
Switch to ZERO ADD.
Set the ZEROS switeh to 037, (options
007 and 003 to 025 with the WORD
SELECT switches at 11110000 0000
00090}.
Press the START pushbutton.
Set the ZERO ADD/NORM/ERROR ADD
GATING lamp FLASHING
DISPLAY TOx 107%
GATING lamp FLASHINSG DiS-
PLAY 1.0 x 107°
NOTE, measurement time 2 seconds
GATING lamp ON.
After approximately 20 seconds
OVERFLOW amp ON.
OVERFLOW lamp OFF.
GATING lamp ON,
After approximately 3 minutes 20
seconds DISPLAY 0.8 x 107
3-28. OPERATING PROCEDURE
3-29. INTRODUCTION
3-30. The 3780A PATTERN GENERATOR/ERROR DE-
TECTOR measures binary errors, code errors, and fre-
quency offset. The measurements may be local using a
loop back method or through a channel under test to a
remote error detector,
3-31. BINARY OR CODE ERROR MEASURE-
MENTS
3-32. To make Binary Error or Code Error measurements
proceed as follows:
3-33. Generator
1.
Select the generator FREQUENCY either internal
(NORM) fy fy fa or external (EXT) from the
CLOCK Г/Р.
Select the generator pattern 2-1 PRES, п bit
word or one of the fixed words.
Select the generator output format, RZ or NRZ
for binary outputs, AMI or CODE including rear
panel CODE format for code outputs.
Connect the generator DATA O/P to the item
under test.
H not using recovered clock connect the genera-
tor CLOCK O/P to item under test.
3-34.
6.
12.
‚ Select
Receiver
Connect data from item under test to receiver
DATA LP,
If not using recovered clock connect ciock from
item under test to CLOCK [/P.
Select DATA THRESHOLD 200mV, 600mV or
GND.
Select receiver CLOCK drive EXT, EXT or RE-
COVERED.
. Select INPUT FORMAT BINARY (RZ or NRZ),
AMI or CODE.
The code will be the code selected with the
rear panel CODE switch of the receiving
instrument.
Note:
MEASUREMENT to be
ERRORS or BINAR Y ERRORS.
made CODE
If the generator pattern selected in step 2 was one
of the fixed words and systematic error detection is
required, select the same fixed word with the PRBS/
WORD switch of the receiving instrument. If sys-
tematic error detection is not required, select one
of the PRBS (9, 15 or 20) positions of the PRBS/
WORD switch on the receiving instrument.
For HDB2/HDB3 code errors, select vocabulary
errors (VOCAB) or violations of violations (VIOLS)
with internai switch A34S1.
+
13. For Binary Errors ensure that synchronism has been
achieved by observation of the RECEIVED PAT-
TERN indicators.
14, Select TIMEBASE and DISPLAY MODE, BER over
10° 10% or 10% clock periods or COUNT, MAN-
UAL or EXTERNAL.
Note: In BER the measurement starts automa-
tically in COUNT MANUAL the measure-
ment is initiated with the START switch,
and in COUNT EXTERNAL the measure-
ment is initiated from an external printer.
15. Ensure that the receiver is operating correctly by
observing the GATING indicator.
3-35. FREQUENCY OFFSET MEASUREMENT
3-36. To set a required generator offset proceed as follows:
i. Select the generator FREQUENCY E fs or fs.
2. Select the OFFSET position of the generator
CLOCK SELECTION switch.
3. Set the receiver MEASUREMENT to FREQUENCY
OFFSET.
4. Ensure correct operation by observing the display
and GATING indicator.
5. Adjust the generator OFFSET control to give a dis-
play of the required offset,
3-37. To measure the offset of an external data input pro-
ceed as follows:
i. Connect the external data input to the receiver
DATA I/P connector.
2. Select the RECOVERED position of the receiver
CLOCK format switch.
3, Connect the receiver CLOCK output on the rear
panel to the generator CLOCK 1/P.
4. Set the generator CLOCK SELECTION to EXT.
5. Select the comparison frequency with the generator
6. Set the receiver MEASUREMENT to FREQUENCY
OFFSET.
7. Ensure correct operation by observing the display
and GATING indicator. |
Operation
3-38. To measure the offset of an external clock input
connect the external clock input to the generator CLOCK
[/P and proceed as in steps 4 to 7 above.
3-39. CONNECTION OF ASSOCIATED
INSTRUMENTS
3-40. INTRODUCTION
3-41. The outputs provided for external recording or dis-
play of the measurement results are described in this sec-
tion. The outputs covered are for a printer, a chart recorder
and a counter.
3-42. PRINTER
3-43. The printer output is designed for direct use with a
Hewlett-Packard 5055A 5050B or S150A printer, The in-
formation from flag signals and display is presented for a
10 column print out in the form:
FEXFYFIOEN
Where F represent the flag information and the remaining
digits represent a BER or COUNT display in the form
X.Y x 10 + N. The output information is in 8421 BCD
form and print information between the error detector
and printer is carried on two lines. The error detector
Printer output socket connections are as follows:
PIN
NUMBER
Fox X #* Y % 1 ©
+
=
a
25 GP 2 TMAIZ2 1H AHI2 TMHIF HIFEHDI2 1 1
56 \ G| HIT ВАНН AlMMISAIHHFFEEHMEBA / 26
KEY
1,2,4,8 BCDWEIGHTING
D HIGH FOR + LOW FOR --
E LOW EXCEPT DURING SYNC LOSS OR
OVERFLOW FLAGS
F LOW EXCEPT DURING SYNC LOSS OR
OVERFLOW FLAGS
G GROUND
H PERMANENT HIGH
| INHIBIT 3780A COUNT CONTROL
FROM PRINTER
Р PRINT COMMAND FROM 3780A TO
PRINTER
Figure 3-2 Printer Output Socket
as Viewed on Rear Panel
3-13
Model 3780A
The flag signal information is coded as follows:
PRINT OUT FLAG
1 OVERFLOW
2 SYNC LOSS
3 CLOCK LGSS
4 DATA LOSS
Y LESS THAN 100 ERRORS
A AÍS
Note: On standard Hewlett-Packard 50554 and 50508
printers V is produced for decimal 13 ar binary
1101 print commands.
3-44. The print command in the BER mode of operation
is given at the termination of each measurement. The print
command in COUNT MANUAL is given when the STOP
switch is pressed and in COUNT EXTERNAL on receipt
of a stop command from the printer. The print command
is a TTL pulse and the minimum print cycle time is 500ms.
3453. RECORDER
3-46. The recorder output provides a high impedance
current source output suitable for connection to a chart
recorder. The output comprises 16 current levels with a
total variation of ImA into an impedance of 10K ohms
max. Two pushbutton switches give Full scale and Zero
outputs for setting up the recorder and there are internal
adjustments for range ImA +: 0.2mA and centre O to
3.5mA. The minimum response time is 500ms. The out-
put levels are as follows:
Level 15 = FSD
BER: Thirteen level signal
LEVELS BER
FSD 15 <107°
14 < 1077
13 < 10°°
12 < 107°
1 < 1074
10 < 107°
9 <107*
8 < 107!
7 < 107°
6 < 10°
4 Sync loss
2 AIS
0 Signal loss
3-14
COUNT: Five level signal
LEVELS REFERENCE
FSD 15 Signal no errors | except
7 Signal plus errors § AIS
4 Sync loss
2 AIS
0 Signal loss
Signal loss indicates clock loss when using an external
clock and data loss when using recovered clock,
3-47. COUNTER
3-48. To make large error counts with greater resolution
than is possible on the 3780A display an external counter
may be connected Lo the rear panel ERROR output socket.
The output is one pulse per error, the pulse amplitude being
1V pk-pk minimum.
The output is inhibited during sync loss.
3-49. OPERATORS MAINTENANCE
3-50. The only routine maintenance which should be per-
formed by the operator is the cleaning of the air filter as
described in Paragraph 3-51.
CAUTION
The replacement of blown fuses should not be
performed without reference to the power
supply troubleshooting procedure Page 8-55,
Power suppiy assembly damage can result if
the correct procedure is not carried out,
3-51, Air Filter Cleaning
3-52. The instrument has an air intake filter which is fixed
to the rear panel with four screws. This filter should be re-
moved and cleaned at intervals of approximately one
month, depending on environment. Wash the filter mesh
in clean soapy water, rinse thoroughly and dry before re-
fitting.
WARNING
The instrument should not be operated
with the air filter removed and the fan
slades exposed.
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