Could anyone with a Socket GPS receiver please verify (with GPSD or rfcomm/cat) that their receiver does in fact emit the RMC sentence of the NMEA protocol? I can't find any information on the web about the messages it sends. The closest thing I can find is a datasheet for some "Trimble Recon GPS Card edition" that claims that it emits RMC and that it includes the "Socket Communications Bluetooth kit", which is a pretty weak connection.

You can check by looking at the NMEA output (with GPSD or rfcomm/cat) and checking if any of the output lines starts with "$GPRMC". If not, it would be helpful if you could tell me all of the message types that the Socket GPS receiver emits (such as the $GPGGA or $GPGSV messages).

It might turn out that the Socket GPS receiver only supports the GGA sentence (not the RMC sentence), which would explain why it's not working with Maemo Mapper. If that is the case, I will retool Maemo Mapper to use GGA instead of RMC (since I think all receivers use GGA). I would prefer to avoid having to support both, since most receivers emit both messages, which would mean doubling CPU usage by having to process both messages.