Transceiver-based spacecraft telecommunication systems with two-way doppler tracking capability

Abstract Recent developments in transceiver-based telecommunication systems at The Johns Hopkins University Applied Physics Laboratory (APL) are described. The transceiver architecture provides inherent flexibility and a cost-efficient way of reducing mass relative to existing coherent transponder systems. The simplified architecture permits ready incorporation of the RF electronics into an integrated electronics module (IEM) along with other core spacecraft electronics. The development of a set of highly integrated S-band transceiver cards for the TIMED spacecraft and the development of an X-band command receiver suitable for deep space missions are described. A unique and very useful feature of the APL transceiver approach is its ability to perform highly accurate, two-way Doppler tracking. This tracking technique is designed to be compatible with existing assets of the Deep Space Network and provides the high accuracy (0.1 mm/s) required for deep space missions.