HL7812 GNSSLOC bug


I have stumbled upon a bug on the HL7812 modem regarding the GNSS functionality. I’m running the latest firmware but the issue is present on all past versions as well. KSRAT is 2.

The NMEA string returns the correct coordinates with the correct longitude “sign”, West:


while once the GNSSLOC is available I get this which shows E instead of W:


Latitude: 51 Deg 6 Min 23.37 Sec N

Longitude: 0 Deg 1 Min 48.10 Sec E


FixType: 3D

HEPE: 1.20 m

Altitude: 205.500 m

AltUnc: 2.0 m




My hunch is that the bug probably only occurs close to the prime meridian where the longitude is 0 degrees and no sign is included in that number, but that’s just a guess.

This issue came up after a customer close to the prime meridian complained about it. All previous code tests passed for East-West and North-South possible combinations.

Come to think of it, no device has been tested West of the Greenwich meridian…

I’ve changed the coordinates for obvious reasons but the correct coordinates show up in the NMEA string, where GNSSLOC gives pretty much the exact location but East of Greenwich a good 200+ miles.