International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, California / Designed for unattended 24 hours-a-day operation in automatic system environments, the 3801 TT&C Digital Processor Unit is the key communication unit for ground stations operating spacecraft, from integration to positioning phase and in-orbit operation. Its architecture and technology concept combine high performance, compactness and modularity. The 3801 TT&C Digital Processor Unit supports multiple formats in a single stand-alone chassis, and incorporates extensive interfacing and functional provisions to maximize effectiveness, reliability and dependability. It supports a number of configurations for satellite control applications and performs :* • Telemetry IF demodulation and transmission of data to a high-level communication interface, with time tagging and display of decommutated parameters, • Command generation, with FSK or PSK and FM or PM modulation at 70 MHz, • Ranging measurements and calibration using ESA, INTELSAT and major standards (tones and codes). In addition, the 3801 TT&C Digital Processor supports a Synchronous Command Generator for spinning satellite in a single stand-alone chassis and includes : • FM signal discrimination, for satellite spin reference information coming from the Telemetry Reception channel, • Synchronization Controller for providing the reference « top » for the transmission of the synchronous tones, • Tones Generation of frequency tones towards the PM/FM Modulator.