Receivers, circuits, and methods to improve GNSS time-to-fix and other performances
An electronic circuit ( 2250 ) for a satellite receiver ( 100, 2200 ). The electronic circuit ( 2250 ) includes a correlator circuit ( 2310 ) operable to supply a data signal including ephemeris data and a subsequent satellite time datum, and a data processor ( 2370, 2380 ) operable to infer satellite time T S from as few as one of the ephemeris data prior to the satellite time datum. Other circuits, devices, receivers, systems, processes of operation and processes of manufacture are also disclosed.
1. A word-position error recovery process for a GNSS receiver wherein a signal stream having a sequence of words, the process comprising:
initially determining an unknown word-position of a word from the sequence of words received from the signal stream;
performing the word-position determining for at least one subsequent word of the sequence of words received from the signal stream to determine a subsequent word position, and if inconsistent word positions result then adopting a more-probable word position; and
using the determination of the unknown word-position to compute a GNSS position solution and a metric of quality of the GNSS position solution, and if the metric of quality thus computed departs from an acceptable level, then performing the word-position determining for the subsequent word received from the signal stream.
2. The process claimed in claim 1 wherein the initially determining of the unknown word-position includes comparing estimated parameters with the word received from the signal stream, and the process further comprises a test to determine whether two of the estimated parameters are both similar to the word received from the signal stream and in such case comparing for the subsequent word received from the signal stream.
3. The process claimed in claim 1 further comprising determining the more-probable word position by determining the word position of the estimated parameter with a maximum similarity metric value by comparison with its corresponding word, and with the maximum thus taken across different words respectively predicted by their different estimated parameters.
4. The process claimed in claim 1 wherein the signal stream periodically includes a satellite time word, and the process further comprises recovering from an error in determining the unknown word position using the satellite time word subsequently.
5. The process claimed in claim 1 further comprising evaluating such inconsistency of word position determinations substantially by comparing their word position difference for substantial equality in duration with a time-of-arrival difference between the word received from the signal stream and the subsequent word received from the signal stream.
6. The process claimed in claim 1 further comprising hypothesizing that the word received from the signal stream and the subsequent word received from the signal stream respectively correspond to a pair of estimated parameters having adjacent positions and applying the similarity metric as a function combining numbers of matching bits between the pair of estimated parameters and the word and subsequent word.