David Stiller of Miami, Florida, asks:
"I’m getting a new Standard Horizon GX2100 marine VHF with integrated AIS receivers, and I’m curious whether it will work with my Shakespeare masthead antenna?"
Gordon West replies:
AIS frequencies are 4.6 MHz higher than normal VHF ship-to-ship channels. However, I’ve done some tests, and Don Henry at Shakespeare Electronics has also conducted some antenna range measurements, and we’ve both concluded that a regular marine VHF antenna will work fine. Shakespeare masthead antennas also have a half-wave matching network that helps broadband reception on the higher AIS frequencies. Of course, for full-blown AIS transceivers, antennas must be specifically tuned to AIS transmitter specifications.
Standard Horizon’s Jason Kennedy stresses the importance of programming the nine-digit MMSI number into your new radio. “To enable collision avoidance, the AIS reception must also be tied into a turned-on ship’s GPS receiver data output 2 conductor line,” he says.
When it is operating, your unit’s screen can capture all AIS targets in your vicinity and you can also make two-way radio contact by pushing a button several times to call up an approaching AIS target.