12-13-2020, 10:04 AM
@calinb The factory test image that came on my Breave Heart had no specific GPS test that I remember. I don't know what diagnostics they're providing with more recent models. It would be difficult to test in a factory without something transmitting a fake GPS signal, so it may not have a specific test.
I used an old Garmin Geko 201 as a cold fix reference before starting on the AGPS stuff. With the Brave Heart I was seeing sats in GPGSV messages even when I didn't have a fix, similar to the Garmin's sat view before fix. If you're seeing nothing in situations where the Garmin can get a fix then something's wrong. Have you tried accessing the modem control interface with a terminal (picocom or similar) when ModemManager is stopped? That may show error messages that aren't present in the NMEA feed - assuming the Quectel interface passes them on via AT messages. Beyond that you might have to go digging in libqmi to find out if there are any lower level GPS diagnostics from the Qualcom interface.
The other more invasive thing to check is the physical antenna connection. I think the GPS antenna is one of the printed ones on the inner frame, with spring contacts to the main board. It's not something I've looked into, so I can't give you more detailed pointers other than looking in the wiki for the mainboard swap instructions for inner frame removal.
I used an old Garmin Geko 201 as a cold fix reference before starting on the AGPS stuff. With the Brave Heart I was seeing sats in GPGSV messages even when I didn't have a fix, similar to the Garmin's sat view before fix. If you're seeing nothing in situations where the Garmin can get a fix then something's wrong. Have you tried accessing the modem control interface with a terminal (picocom or similar) when ModemManager is stopped? That may show error messages that aren't present in the NMEA feed - assuming the Quectel interface passes them on via AT messages. Beyond that you might have to go digging in libqmi to find out if there are any lower level GPS diagnostics from the Qualcom interface.
The other more invasive thing to check is the physical antenna connection. I think the GPS antenna is one of the printed ones on the inner frame, with spring contacts to the main board. It's not something I've looked into, so I can't give you more detailed pointers other than looking in the wiki for the mainboard swap instructions for inner frame removal.