TM 11-6625-1668-12
until a new measurement is initiated. In order to initiate a new measurement set the RESET switch to MAN and
release to the OFF position. Normally during error rate measurement the RESET switch is operated in the
MAN and OFF positions to allow sufficient time for a complete measurement. Operation in the AUTO position
is not recommended as the auto reset period of 3 to 5 seconds will only allow measurement for one thousand
bit times above 600 baud. The nixie display is limited to a maximum error rate of 99 errors per thousand or
million bit times. When this limit is reached the OVERFLOW lamp illuminates and the number of errors
displayed becomes invalid. The time required to complete an error rate measurement depends on the
operating speed of the analyzers. Each operating speed and the total time required to complete a thousand or
million bit time measurement is listed as follows:
Operating
Time required to complete error rate measurement
Operating
Time required to complete error rate measurement
speed in
speed in
3
6
3
6
bauds
10 bit times
10 bit times
bauds
10 bit times
10 bit times
37.5
26-2/3 seconds
7 hrs 24 min 26-2/3 secs
300
3-1/3 seconds
55 min 33-1/3 secs
45.45
22 seconds
6 hrs 6 min 40 secs
600
1-2/3 seconds
27 min 46-2/3 secs
50
20 seconds
5 hrs 33 min
1200
5/6 seconds
13 min 53-1/3 secs
61.12
16-2/5 seconds
4 hr 33 min 20 secs
2400
5/12 seconds
6 min 66-2/3 secs
75
13-1/3 seconds
3 hrs 42 min 13-1/3 secs
43 00
6/24 seconds
3 min 23-1/3 secs
150
6-2/3 seconds
1 hr 51 min 6-2/3 secs
9600
6/43 seconds
1 min 44-1/16 secs
(6) Typical operation ERROR RATE. For the purpose of this procedure two analyzers are required;
one for transmitting and the other for receiving. The transmitting analyzer pseudo-random output (6 volts,
MIL STD 188B) at 2A3J3 pins 3 (data) and 24 (ground) is connected to the bridging input of the receiving
analyzer. The initial control settings are listed below:
Control
Position
Control
Position
POWER switches (transmit and
OFF
ERROR DEFINER thumbwheels
49 or 00
receive). ..........................................
(receive). ......................................
DISPLAY MODE switch (transmit) ...
TEST MODE
BAUD RATE switch (transmit and
600
receive). .......................................
ERROR RATE 103
DISPLAY MODE switch (receive) .....
INPUT switch (receive) ................
HIZ
CODE LEVEL switch (transmit) .......
SYNC
MARK POLARITY (receive) ..........
- (negative)
NOTE
The position of unmentioned controls will not affect operation in this mode.
(a) Set the POWER switches to ON and reset the nixie display.
(b) Read error rate per 1000 bit intervals on the nixie display when the measurement period is
complete. Errors counted have exceeded one percent distortion.
NOTE
The measurement period begins when the SPACE/START lamp illuminates and ends when
the MARK/FINISH lamp illuminates. The overflow lamp illuminates when the total number
of errors exceeds 99.
(c) Set the DISPLAY MODE switch to 106, reset the nixies and read error rate per 1,000,000 bit
intervals.
(7) PEAK MON. The analyzer is used as a distortion monitor when the DISPLAY MODE switch is set
to PEAK MON (HITS). In this operating mode the analyzer becomes a full period peak monitor registering on
the nixie display, one hit for every M/S or S/M transition that exceeds a preset distortion threshold. When peak
hits are counted, distortion measurement in the analyzer are made as usual except that the distortion measure-
ment is no longer displayed. In place of the distortion reading, the nixie display indicates the number of times
the preset distortion threshold has been exceeded (hits). The distortion threshold is established by the setting
of the THRESHOLD % DISTORTION thumbwheel switches. The threshold is set for the maximum permissible
distortion in 1 percent increments from 00 to 49. Peak hits are detected by comparing the actual distortion
present on the data signal with the distortion setting of the thumbwheels. When the actual distortion on the
circuit under test is greater than the threshold setting a hit is counted, and the nixie display is updated. If, how-
ever, the distortion is equal to or less than the setting of the thumbwheels, hits are not counted and the nixie
display remains unchanged. The highest number that can be displayed on the nixie readout is 99. Therefore
when the number of hits counted reaches 99 the nixie display begins counting from 00 again and the OVER-
FLOW lamp illuminates. Peak measurements are made with RESET switch in the OFF position. If this switch
is set to AUTO the peak hit measurement is interrupted every 3 to 5 seconds. To reset or destroy old peak hit
readings set the RESET switch to MAN and release to the OFF position. This allows the analyzer to make a
new peak hit measurement.
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