Table 3-1. Operator Controls, Indicators, and Connectors-Continued

TM 11-5820-803-12

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