The Model 792 Phase Modulator is a Modular Subcarrier System. The Model 792 includes up to two independent modulator channels with Upconverters providing outputs at S-Band and/or L-band frequencies. All functions within the Model 792 are controlled through the local front panel display and keypad, or the remote control port.

The unit is supplied with one or two channels. Each modulator channel contains a Linear Phase Modulator and an Upconverter. The phase modulator accepts modulating frequencies up to 6 MHz. The RF output of the unit is produced in three stages. The first IF is set to 15 MHz. Linear multipliers (instead of saturated diode mixers or step recovery diodes) are used to upconvert to the second IF of 140 MHz. Using linear multipliers results in significantly reduced harmonics and IM (Inter-Modulation) terms and therefore, eases filtering requirements.

The 140 MHz IF signal is translated to higher frequency bands by the Upconverter. The Upconverter accepts the 140 MHz subcarrier from the Phase Modulator and provides upconversion to LBand and S-Band frequencies. A separate output is provided on the Model 792 for the first IF signal. The lower IF output is normally set to 15 MHz for 140 MHz output to the Upconverter. Tunable Phase Modulated subcarriers may be programmed up to 20 MHz. if upconversion is not used.

A menu-type front panel user interface is presented to the operator on a high contrast 2-line by 40-character vacuum-fluorescent panel. Operator entries are made on a 20-position keypad. Formatted computer generated commands are used to control the unit by way of an RS-232 or IEEE-488 remote control port.