comp data format:

YYYYMMDD HHMMSS $HCHDM,DDD.D,M*CC

where YYYYMMDD = Date as year, month, day
      HHMMSS   = Time as hour, minute, second
      $HCHDM   = NEMA sentence identifier
      DDD.D    = Compass heading in degrees
      M*       = NEMA sentence characters
      CC       = NEMA sentence checksum