NMEA Parser update

We have agreed on a protocol for the file that the microcontroller stores on the SD card.  The file will contain normal NMEA data, mixed in with depth measurements.  Since all NMEA data begins with a  '$' sign, the depth measurements are easily singled out.  Also, since the GPS only updates one time per second, and we are able to take several depth measurements during that time, the desktop application takes an average of all of the depth measurements taken during the GPS refresh time.  The regex that I am using to pull the GPS coordinates is


self.gpgga = re.compile('^\$GPGGA,\d+,(?P\d+\.\d+),[NS],(?P\d+\.\d+),[EW],\d,(?P\d+),.*,(?P\d+\.\d+),M');