TM 11-5820-803-12
Table 3-1. Operator Controls, Indicators, and Connectors-Continued
Controls, indicators, or connectors
Function
MONITOR section
MONITOR meter
Specific function of meter is dependent on position of METER switch.
METER, 11 position rotary switch
OFF-Disables Meter
+5-Measures internal +SV dc supply voltage
-5-Measures internal -5V dc supply voltage
+15-Measures internal +15V dc supply voltage
-15-Measures internal -16V dc supply voltage
XMT SYNTH-Checks phase detector output voltage in transmit
frequency synthesizer.
RCV SYNTH-Checks phase detector output voltage in receive
frequency synthesizer.
AGC-Measures automatic gain control voltage in receiver.
VCXO-Checks voltage controlled crystal oscillator control voltage in
receiver.
ERROR COUNT-Displays voltage proportional to error rate measured
by internal error comparator. Scale factor is error rate (percent) =
meter reading + 4. Function displayed depends on TRANSMIT
SOURCE and TEST switch settings.
1. With the TRANSMIT SOURCE switch in the OPERATE or LINK
positions, the error comparator monitors the standard data and
clock outputs of the receiver. If the 2047 bit sequence (coded or
uncoded) is received from the communications link and the
appropriate decoding is selected, the error comparator measures
the bit error rate provided by the receive link.
2. With the TRANSMIT SOURCE switch in the TEST position, the
error rate measurement depends on the TEST switch setting.
SIG/NOISE-Displays a voltage derived from the operation of the receive
bit sync by the internal error comparator. Indication may be used
as an estimate of receiver input Eb/No, or receiver output bit error
rate (para 2-10d).
DATA A and B indicators
Indicators illuminate to indicate the logic state present at
internal error comparator data input.
1. DATA A on indicates a logic 1
2. DATA B on indicates a logic 0
The data monitored at the internal error comparator input
is dependent on the TRANSMIT SOURCE, METER, and
TEST switch settings.
CLOCK A and B indicators
Same as DATA indicators except that clock is monitored.
TRANSMIT indicator
Illuminates to indicate presence of modulation and adequate
power at 70 MHz output.
TEST, seven position rotary switch
Enabled by placing the TRANSMIT SOURCE switch in the
TEST position, which also:
1. Connects the internal 2047 bit sequence generator to the
transmitter baseband conditioner input.
2. Internally switches the 70 MHz receiver input from the terminal
output to an attenuated sample of the 70 MHz transmitter output.
3. Connects the LOS/cable receiver input to the LOS/cable driver
output test signal.;
The TEST switch selects the data and clock inputs to the internal error
comparator and, in position 3, injects the sequence at an additional
point in the circuitry.
Position --Connects the internal error comparator to monitor the internal
2047 bit sequence generator outputs.
Position 2 Connects the internal error comparator to monitor the
transmit bit synchronizer outputs.
Position 3-Connects the receive bit synchronizer input to the internal
2047 bit sequence generator output, and connects the internal error
comparator to monitor the receive bit synchronizer outputs.
Position 4-Connects the internal error comparator to monitor the
standard data and clock outputs (end-to-end test).
3-3
