Improved Transponder for Earth/Spacecraft Communication

A prototype of a relatively inexpensive S-band transponder has been developed for use aboard a spacecraft as part of a NASA space- craft tracking and data network (STDN). The transponder design incorporates recent advances in digital processing of received radio signals. Notable features of the design include flexibility in the choice of operating modes and “smart” acquisition of signals. The transponder design could also be adapted to military ground-based satellite communications and tracking and to commercial Earth/satellite communication systems.