One question we get asked a lot when customers are looking to buy an AIS Class B transponder is: "can I use my existing GPS instead of needing to install yet another GPS antenna on my rail"? Up until recently, the answer to this question has been "no - you need to use the internal GPS system in the transponder and connect a compatible GPS antenna in order for the transponder to work correctly". Now we have a different answer!

Before describing what's changed it is worth reviewing what an AIS transponder does and how it works.

Very simply, an AIS Class B transponder takes your GPS position and other data related to your vessel (e.g. the boat's MMSI and vessel name) and creates a NMEA sentence or two which is transmitted via VHF at regular intervals (see our FAQ for all the details). A remote AIS receiver can then receive and decode the NMEA sentences and send the data to an AIS display. But if the transponder does not have a valid GPS position, everything grinds to a halt and transponder ceases to send out position updates. In order to ensure that GPS data is available to the transponder system, all manufacturers, as far as I know, include an integrated GPS system in the transponder unit. This makes it easy for installers and users. Simply install and connect a GPS and VHF antenna to your transponder black box and your transponder should start working as soon as power is applied.

Now the folks at AMEC have come up with a new feature that is the best of both worlds. Our very popular AMEC CAMINO-101 Class B AIS transponder can now either use its internal GPS system coupled with the AMEC external antenna or it now supports using an external GPS device connected through the inbound NMEA port. This means that you could use a single input/output NMEA connection with a chartplotter to send AIS data to the chartplotter from the CAMINO-101 and receive GPS data back to the CAMINO from the chartplotter. This can be used as an alternative to purchasing and installing a dedicated GPS antenna for the CAMINO. Just be sure to use the same baud rate on the NMEA ports for both devices. In most cases this will be 38400 baud.

As long as the physical GPS antenna is not connected to CAMINO-101 before powering up, the CAMINO-101 will take a GPS signal from external GPS source if any. There is no need to turn off the internal GPS, it will be done automatically by the firmware. Keep in mind that the internal GPS source has higher priority. That means, if the CAMINO GPS antenna is connected, the CAMINO-101 will use its own GPS even though an external GPS source is also available.

The CAMINO-101 supports the following inbound NMEA sentences on the NMEA port: RMC, GGA, GBS, GSA and HDT.

As a result of this new capability, we now offer the CAMINO-101 as an individual item for $459.00. If you want to use the internal GPS, be sure to add the optional GPS antenna when you make your purchase. The combined price is still under $500.

Happy New Year and have a safe 2012 on your boat!