AIS 2009, forward in all directions!
My coverage of the NMEA Conference last October was dominated by Class B AIS (and largely—doh!—a vessel naming issue that turned out to be immaterial). But in fact I also learned how AIS is getting into all sorts of marine systems, and was reminded of that by the recently published minutes of the Oct. 3 GMDSS Task Force meeting I attended. One item of note is the prototype AIS SART seen above, overlaid on a slide of the impressive test results such SARTs are generating. Most recreational boaters aren’t familiar with Search and Rescue Transponders, but they are standard gear on ship lifeboats, and heretofore used radar amplification—like a RACON—to help rescuers home in the last few miles. I’ve seen a live demo and wasn’t very impressed, and I’ve even heard buttoned-up GMDSS regulator types complain that it was not a very effective technology. Well, guess what? AIS SARTs work much, much better. The specifications aren’t yet wrapped up, but interestingly AIS SARTs will apparently broadcast just once a minute, but with eight message bursts to compensate for wave interference. Is there lots more AIS may do? You betcha…
How about replacing the 121 MHz homing signal send out by EPIRBS with a longer range, more accurate, and accessible-to-most-any-boat AIS signal? A committee is looking into it. Why not use AIS to broadcast local “NOAA PORTS data, weather and other security and environmental information.” Apparently it’s already being tested in Tampa, Florida (slide below, full PDF here)! Couldn’t AIS be used for the global Long Range Identification and Tracking (LRIT) system being mandated on ships? Well, maybe, and Orbcomm already has some AIS receivers in space. And while it’s not mentioned in the Task Force minutes, and while AIS Base Stations—capable of changing every transponder’s frequency and other serious stuff—will only be run by the government (understandable!), I did hear the USCG representative say that private informational AIS transmitters will be treated like Private Aids to Navigation. So, hey, your yacht club or harbor master may eventually be delivering useful nav info via AIS.
Now, it’s true that much of this involves big ships and that most of our AIS plotting devices don’t yet understand much beyond standard vessel messages, but I hope that the AIS nay-sayers—”too many targets!”… “screens too busy!”—will note that the conservative folks who actually manage this system don’t seem concerned about overburdening it. Meanwhile, my latest ode to Class B is up at PMY, along with verbiage on the Simrad AI50 (which I hope to test once I get out of NYC), the Furuno FA-50 (more impressions here), Digital Yacht’s SPL250 AIS/VHF/FM antenna splitter (more Panbo-style detail here), and Icom’s MXA-5000 AIS receiver (which I’m told is now shipping, and I’d also like to try). Plus, Navagear is on the AIS target to DSC VHF call bandwagon, a feature that’s gotta happen, right? AIS-wise, at least, 2009 is going to be a good year.
Proposed satellite AIS receivers will ignore Class B AIS transmission to avoid overload. At least that is the proposal based on simulation by the EU. The proposal goes further stating that a 3rd AIS frequency (one of the DSC CH 70 gardbands), which is allocated worldwide be used with an abbreviated message as a Class A uplink to satellites until shore-based AIS basestation transmissions are in range at which point the Class A AIS would cease transmissions intended for satellite reception.
I haven't seen any specifications for the Orbcomm AIS receivers in order to see if they conform to the recommendations regarding ignoring Class B but they may will. Since there is no agreement on using the 3rd AIS frequency I imagine the Orbcomm satellites receive existing Class A transmissions on the existing frequencies, one of which is allocated worldwide.
Cheers and Happy New Year to all.
Richard D.
s/v RED