SYSTEM OPERATION-continued

TM 11-6625-2975-40

1-14. SYSTEM OPERATION. (CONT)

Rf modulator assembly A3 uses microprocessor-generated data it receives through the control bus to

produce rf frequency control signals. It also combines modulating signals from the audio generator in

controller/audio assembly A2 with rf carrier from the A4 synthesizer assembly.

Rf frequency control signals from rf modulator assembly A3 are applied to synthesizer assembly A4.

This assembly uses control signals to produce selected rf carrier frequency and rf status information.

NOTE

Rf status information verifies that the synthesizer is locked on frequency.

Rf carrier frequency is then applied to assembly A3 for modulation.

Rf status information also is

applied to assembly A3.

Rf modulator assembly A3 sends frequency and status information supplied by synthesizer assembly

A4 back to the microprocessor through the control bus. The microprocessor in turn supplies this

information to front panel assembly A1, again through the control bus. Front panel assembly A1 uses

the information supplied by the microprocessor to produce appropriate front panel displays.

Modulated rf signal and an attenuator control signal are applied through digitaiiy-controlled attenuator

A6AT1 (p/o assembly A6) to the RF OUT connector. Attenuator control signal determines the amount

of attenuation required for the digitaliy-controlled attenuator to produce an rf output signal with the

selected output Ievel.

Simulated ground station signal is applied from the RF OUT connector to the receiver under test.

Controller/audio assembly A2 applies composite and auxiliary signals to connectors on the rear of the

test set. Rf modulator assembly A3 applies a demodulation signal to a third connector on the rear of

the test set.

Chassis assembly A6, which includes digitally-controlled attenuator A6AT1, contains all the test set's

interconnecting wiring.

Power supply assembly A5 produces all dc voltages needed for test set operation.

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