The GDP Space Systems’ Model 484 is a full featured SGLS FSK/AM Modulator / Demodulator (Modem).

Either Ternary (1, 0, S) or DiBit (48 bit frame) commands are applied to the SGLS modulator, which produces the SGLS standard FSK/AM modulated signal. This signal is combined with an externally supplied digital data stream (usually the Ranging PRN) in a linear signal summer to produce a composite output ready for application to an up-link transmitter.

An Auxiliary data stream input may be used to produce a binary FSK output consisting of tones selected from the 1, 0, and S tone-set.

The FSK/AM signal is decoded into its original components (1, 0, S) by the SGLS Demodulator. The demodulator is capable of automatically detecting and decoding one of two predetermined signaling rates. No programming is required.

Two standard Remote Control interfaces are provided. Both RS-232 and IEEE-488 interfaces are installed. Optionally, an Ethernet interface is available. All remote control commands and responses are based on a simple ASCII protocol.