GPS returning incorrect coordinates and long lock time

[michaelshipman]

Will have to put in actual numbers later but the coordinates from the receiver are pretty wrong, still in Maryland but probably 30ish miles away. UTC time is correct though.

I'm not sure why this is the case given that it was working a week or two ago.

Coupled with this issue is 20+ minute lock times for position.

I think my best bet right now is to reseat the GPS receiver, maybe over the last few weeks and a launch a solder joint or two have partially failed.

[michaelshipman]

Replaced the MIA (from rev 0 build) and the antenna (new) and left running for a bit on the picnic table outside of MFG, not sure how long but I don't think more than 15 minutes.

Got time again but nothing else.

[michaelshipman]

Going to put the RTC crystal on, RTC_O is supposed to be grounded when not used so I wonder if it's causing EMI issues

[michaelshipman]

also the trace width was 0.22mm and JLC says it should be 0.1565, kicad calculator says 0.2

[michaelshipman]

Viewing the spectrum, it's not the worst I've seen but not like the nice pretty one in the ublox manual. I'm not sure what the spikes are for one thing. It seems like a decently well formed spectrum and considering I'm in my apartment next to the window the received signal strength doesn't seem unrealistic.

For future reference: the UBX-MON-SPAN is in View > Messages > Scroll down to Mon

[michaelshipman]

Oh also GPS baud for the MIA is 38400

[michaelshipman]

I revved the board to T1002 to tune up the GPS section, have not assembled or tested yet but tuned the antenna line impedance and improved grounding

[michaelshipman]

So I'm a bit of a dumb dumb, the NMEA lat long format confused me a little bit

This is what I got when the GPS did eventually get lock: 3859.55949,N,7656.33880,W

This is actually 38 + (59.55949 / 60) = 38.9926581667, and -76 + (56.33880 / 60) = -76.93898

Which is right on MFG actually

I still can't get it to lock consistently or quickly, but it does actually work when it does get position fix