An S-band tracking system employing one way Doppler applicable to the Tracking and Data Relay System (TDRS) has been evaluated. This evaluation is limited to the measurement system parameters. Orbit determination uncertainties, such as those associated with modeling of the geopotential function, solar pressure and atmospheric drag, are independent of the measurement system and therefore are not included in the evaluation.nThe analysis assumes state-of-the-art components such as spacecraft oscillator long term stability of one part in 108 and ground station oscillator stability of one part in10. Signal characteristics comparable with the present (1973) ranging systems are utilized in the analysis.nPredicated upon measurement system parameters, position un certainties for the low orbiting spacecraft vary from 5 meters to 2 kilometers along track, 4 meters to 1 kilometer cross track, and 1 meter to 180 meters radially depending upon the tracking geometry and the high satellite position and velocity error assumptions.
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