Actually most of these use either an FTDI or a Prolific serial to USB chip, as the GPS chips themselves tend to have serial outputs, so these add-on GPS look like a COM port outputting standard NMEA sentences. Similarly the Bluetooth connected GPS units also look like COM ports outputting NMEA.there are add on GPS's via USB, which would presumably have API's built by the vendors. These would need to be wrapped for use with B4j. It is unlikely that, if available, they would share a common API.