1. It loses precision in the conversion run (e.g. from 00838.2842 to 00838.284)
> Where is this, the NMEA output?
Yes, the former is the NMEA output of the device directly, the latter is the output after is has gone through GPSBabel. The reason I use GPSBabel to convert NMEA to NMEA is threefold:
1. My device splits the log into 512KB files; I use GPSBabel to re-join them and split them into daily files.
2. While doing this I also filter out track points with less accuracy (DOP and # of satellites)
3. At the same time I also produce a GPX and a Garmin file.
2. It drops all satellite information (satellites visible in the $GPGSA record, all of the $GPGSV records)
>Fundamentally, GPSBabel processes positions reported by a GPS and isn't terribly interested in which SVs were used in the >reporting of that position. So you're correct that if that information is critical to you, you need to keep it out of GPSBabel's reach >because we will discard it.
It’s not critical now, but who knows about the future ;-) I would consider the satellite information part of the overall accuracy information about a particular track point, so it may be of more than academic interest. I looked at the source code and realized that it would be a bit of work to implement this, because it affects a central datastructure used by every conversion library. Plus it needs a bit of thinking, because the $GPGSV is usually not recorded as often as the other NMEA information.
Best regards, Martin