* https://ciechanow.ski/gps/

* 2022: https://news.ycombinator.com/item?id=29981188

* 2023: https://news.ycombinator.com/item?id=36180316

* Others: https://news.ycombinator.com/from?site=ciechanow.ski

Standford's "An Introduction to Satellite Navigation" course is also instructive (recorded 2014):

* https://www.youtube.com/playlist?list=PLGvhNIiu1ubyEOJga50LJ...

I'm working on a presentation now to explain how GPS works to second graders. If they understand it, I'll take some photos and do a write-up.

I ask because I do a lot of backcountry hiking, camping, and foraging and rely on true GPS-only navigation. My most recent two phones (iphone and pixel) have noticeably worse GPS performance than previous phones, and I even changed OS ecosystems mostly hoping for better GPS, but it didn't help. Maybe I've had bad luck, but two noticeably bad phones in a row seems like it may be a pattern.

And is there any way to find phones with very good GPS performance?

Watches that use GPS for altitude are terribly inaccurate

It is interesting to run the opensource GPSTEST app on a smartphone and watch the MSL "settle" over time but each sat seems to disagree

* https://github.com/barbeau/gpstest

btw watches are now getting THREE multi-band L1+L5 GPS chipsets, should help things

quad-band GNSS coming soon too!

* https://the5krunner.com/2026/03/06/tri-band-gps-garmin/