Patent ID: 8184046
Filing Date: 2012-05-22
Classification: G01S

Abstract:
1. A time reference system for generating a time reference from signals produced by a global navigation satellite constellation, wherein the system comprises: a satellite signal receiver having a radio frequency stage configured to receive and down convert code-modulated signals from a plurality of satellites and a correlator configured to receive, track and decode the down-converted satellite signals to provide signals containing partial pseudo-range measurements for respective satellites, and a data processing arrangement configured to receive signals containing assistance data from a source other than the received and down-converted satellite signals and the signals containing partial pseudo-range measurements, to perform data-bit synchronisation in which the bit edges of a data bit stream carried by the received satellite signals are identified, to perform correlation of pre-selected data sequences in the data stream to resolve time ambiguities, and to compute a time reference signal based on the assistance data, the partial pseudo-range measurements and code-tracking outputs from the satellite signal receiver, the data-bit synchronisation and the data sequence correlation.