Class B AIS transponders must have a dedicated GPS and can't share one with another unit. And they cannot use NMEA-0183 data from another GPS. This is a type approval certification requirement. As a result, all Vesper Marine AIS transponders must use their own dedicated GPS antenna.
However, you may be able to eliminate and existing GPS antenna by utilizing the NMEA output from the Vesper Marine AIS transponder. The NMEA 0183 for all of our transponders, or NMEA 2000 for supported transponders, provides a GPS data feed to other equipment. The same is true of the USB port on all Vesper Marine transponders.
So as an example... if you currently have another GPS plugged into your computer using a USB converter... you can eliminate that GPS and the USB converter and plug your Vesper Marine transponder directly into your computer since it has USB. For Vesper Marine transponders with WiFi, you don't need a physical connection.... you can use WiFi to send GPS+AIS+NMEA data to your computer or your mobile phones or tablets/iPads.
Or if you can use your Vesper Marine transponder's GPS to supply data to a plotter, radar and/or VHF radio too. As a result, you may find this allows you to eliminate one of those GPS antennas too.