Model of receiver design flaw - crucial for Huygens space mission recovery

An analytical model is presented to recover from a current design flaw in the Huygens space mission relay-link receiver. The model of the faulty implementation of a data transition tracking loop (DTTL) is a driver for the trajectory redesign leading to the new relay-link geometry of the Huygens mission. This recovery shall allow for a successful data retrieval from the probe during its descent towards the Saturn Moon Titan, despite the tracking deficiency in the given symbol synchronizer. The model of the DTTL implementation is presented in terms of system-level parameters: link performance (E/sub s//N/sub o/), symbol transition density P/sub t/, and input symbol-rate offset /spl Delta/F. The analytical model has undergone extensive successful verification during in-orbit tests and performance mappings since the discovery of the anomaly.