TDRSS Telecommunications MA Return Channel

Abstract

The Tracking and Data Relay Satellite System (TDRSS) relays signals to and from ground terminal and user satellites. No signal processing is done on the satellite and as many functions as possible have been removed from the satellite and implemented in the ground terminal. The multiple access (MA) users serviced by the S-Band thirty element phased array on the satellite require the capability to form up to twenty simultaneous tracking antenna beams by phase and amplitude weighting the individual antenna elements in the ground terminal. Frequency division multiplexing is used to transmit the 30 antenna elements to the ground for beamforming. Phase and amplitude uncertainties build up over time between the antenna elements and the beam processing on the ground. To optimize and maintain required performance, a calibration technique is required to estimate the channel weight correction table for the MA return link.