$GPGGA reads NMEA gps string GGA the example is a valid string to be used for test.

 $GPGGA help
   $GPGGA gps nmea string.
     example: $GPGGA,135816.000,5558.2531,N,01224.9809,E,1,09,0.9,34.7,M,41.3,M,,0000*67