3 ms·
Time to get a fix is mostly what clever techniques the receiver uses. There are various papers demonstrating getting a fix that is probably correct with just
by pifm_guy 4y ago
Time to get a fix is mostly what clever techniques the receiver uses. There are various papers demonstrating getting a fix that is probably correct with just a few milliseconds of signal and then lots of processing.
You also have to cut corners to get a (probably correct) fix fast. Things like assuming the almanac hasn't changed since last time, the user hasn't moved more than a few hundred miles, the system clock hasn't drifted by more than a second or so, and no satellites have become unhealthy.
- chrisfosterelli 4y agoI've always noticed my Garmin watch gets a fix extremely fast except for the first time I use it after traveling somewhere new. That first one always takes several minutes.
- paulmd 4y agoyes, the math is significantly simplified if you assume you haven't moved. cold start is always much slower (and is called out as such in most GPS datasheets)
- eru 4y ago> Things like assuming the almanac hasn't changed since last time, the user hasn't moved more than a few hundred miles, the system clock hasn't drifted by more than a second or so, and no satellites have become unhealthy. If you are using a smartphone, you could probably validate those assumptions via your other sensors?