> What can the firmware do if it decides that it doesn't like a satellite? The > GPS receiver does the math and sends over the PPS. How would the firmware > adjust that calculation to not use a particular satellite?
Hal, Just let the firmware do what it does. The detection and adjustments can be done off-board. Not unlike what all the pros do with post-processing. Look at the Oncore @@Ha or @@Hn message -- you get the timing solution contribution for each SV. What you see in the hardware 1PPS is simply a real-time, uneducated, equally weighted mean of this calculation. It works pretty well. However, if you can apply an educated manual weighting (perhaps based on a long- or short-term history of SVN, Az/El, signal levels, std dev from mean, etc.) to each SV in the solution, it seems to me it is possible to calculate a virtual 1PPS that is more accurate than the real 1PPS. When you think about it, a static elevation mask, ignoring the role of azimuth, ignoring your antenna 2D tree profile, ignoring S/N ratios, and treating all SV in the sky as perfecty equal is simple, but dumb. Someone on the list could make a fun project to explore these algorithms to improve the performance of Oncore, TBolt, or u-blox timing receivers. I've looked into this for the Oncore and TBolt but haven't posted anything. Contact me off-line if interested. /tvb _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
