The recovery of buffered telemetry data for future low cost space missions

It is clear that the cost efficiency is becoming a major driver in future space missions. Because of the constraints on total cost, including design, implementation and operation, future spacecraft are limited in terms of their size, power and complexity. Consequently, it is expected to have future missions operate on marginal space-to-ground communication links which, in turn, can pose an additional risk on the successful scientific return of these missions. For low data rate and low downlink margin missions, the concept of buffering the telemetry signal for further signal processing to improve data return has been widely adopted. The paper describes techniques used for post-processing of the buffered telemetry signal segments (called gaps) to recover data lost during acquisition and resynchronization. Two methods, one for a closed-loop and the other one for an open-loop configuration, are discussed. Both of them can be used in either forward or backward processing of signal segments, depending on where a gap is specifically situated in a pass