Depending on the gps, there can be a dead-reckoning mode that will extrapolate things for some time (often settable). The pps may or may not follow.
gem@rellim.com said:
> Looking for that check in the gpsd code, I do not see it in the PPS path or
> in the NMEA path. I wonder when that disappeared? That may explain some
> things... I'll go add that back in now.
I think there is another piece of fine print in that area. I'm not sure
where I saw it, probably one of the Garmin docs.
The idea is that you can't trust the first few seconds of data when it
switches from not-enough satellites to enough. I've seen it give bogus
position (way off) marked as valid. I think they all happened right after
recovering from not-enough-satellites.
I'll scan log files if anybody wants examples.
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