The GDP Space Systems’ Model 787 Dual SGLS Signal Generator provides multi-channel Space Ground Link System (SGLS) compatible Telemetry Tracking and Command (TT&C) and communication subcarrier signals.

The unit includes one FSK/AM/PM Modulator, three BPSK Modulators, a Ranging Tone Generator, and two Signal Summer/Level Control modules. The unit also accepts SGLS dibit encoded data/clock and auxiliary data/clock inputs for FSK modulation; three data and clock inputs for BPSK subcarrier modulation; a ranging signal input for Range Tone output selection; and an external analog input channel. An internal psuedo-random noise (PRN) generator data and clock can be selected in place of any of the external data inputs. Two independent Summer modules each provide a composite output. The four Modulator output signals, the digital baseband output of the Ranging Tone Generator, and the external analog input signal are distributed to both Summers.

For each Summer, up to four-of-seven signals are combined to produce a Composite Output signal. Individual signal level and ON/OFF control is provided for the four selected signals on each Summer, as well as selectable attenuation of the composite output. All user selectable functions are controlled through either the local front panel display and keypad, or the IEEE-488 remote control port.