AIS MOB devices, we're in the learning phase!
One of the great things about the new AIS MoB beacons, like the recently FCC-approved Kannad SafeLink R10, is that they can send a short test signal over the air so that you can see how well your AIS plotter has been programmed to deal with one. But the fact that I've been encouraging folks to do just that makes it even more imperative that I report on a bug in very recent Garmin MFD software versions 7.30 7.20, 4.30 4.20, and 3.80 3.70. (See comments on the R10 entry above for more detail, but you probably don't have the bug unless you updated your Garmin in last few weeks). While Garmin purportedly did a great job of programming its displays to respond usefully to an AIS MoB, apparently the test signal from an R10 can cause its MFDs to shut down, which was just discovered in Newport where the Bermuda Race fleet is gathering...
In fact, Garmin has dispatched two techs to Newport with 50 SD cards and are offering to do onboard software updates today and tomorrow, which is pretty impressive (especially since they make it so easy to do yourself via download). I'm not sure if it matters whether the AIS MoB test messages are received over NMEA 0183 or 2000 -- which Garmin is particularly good at, as recently discussed -- but who would have guessed that they could sometimes cause an MFD to shut down a mile or more away?
Oddly enough, this situation is this week's second reminder that we all have a lot to learn about this new use of AIS. First came some info I picked up in Charlie Doane's Kannad R10 test on WaveTrain. Yes, it was the inimitable Mr. Doane who probably created that R10-equipped MoB dummy pictured above, and rather than using the short test signal he got USCG permission to do a real test. Which was good in a way, as the Portland, ME, CG were able to report that they saw the signal four miles away. But not so assuring in the sense that "they also told us they saw nothing that suggested to them that the R10's transmission was in fact a distress signal."
As I understand it, any AIS plotter that receives an AIS MoB or SART signal is going to display it, because they use AIS message #1, the same dynamic data (position, speed, etc.) message as Class A transponders. And that message contains a particular Navigation Status field of "14" which is a tip-off that the sender is a distress device. Plus each SART MMSI, and only SARTs, begins with "972 970" {MY mistake!} and each AIS MoB MMSI begins with "972." Except that another thing I learned from Charlie's article is that the number is often called an ID instead of an MMSI, which makes sense as they are not unique to a vessel or even referenced to one. I like the term "MMSI-like ID number" which I found in an early Jotron commercial level AIS SART document.
At any rate, the USCG NavCen "MMSI Overview" page now delineates this difference between AIS SARTs and MoB devices (below), and also describes an MMSI-like ID scheme for EPIRB-AIS devices that we haven't really heard about yet. So the learning will continue! What I don't know right now is what the AIS MoB's like the Kannad R10 put in the SRM (Safety Related Message, #14) that they also transmit. Is is "ACTIVE SART" or "SART TEST" like the EasyRescue personal AIS SART I tested -- which was developed before the AIS MoB standard was fully developed -- or maybe "ACTIVE MOB" and "MOB TEST"?
And what you probably don't know yet is what your AIS plotter will show besides a target with an unusual MMSI-like number. Will it throw up the SRM message as an alarm and even offer to set up a MoB waypoint, like the Raymarine E-Wide above did for the EasyRescue? I still have the EasyRescue and will test it with the displays I've got networked the Em-Trak B100 -- including a Garmin 7212, which I'll try before and after software updates -- and I'll put up more screen shots on this entry soon. If you've tried this sort of test, please send an image or just let us know how it went in the comments.
PS 6/14: Well, I got the title right! Almost no AIS plotting device I tried on Gizmo today treated the EasyRescue SART very well. The exception was the Raymarine e7, which alarmed and threw up an AIS SRM Alert "SART Test" with a Goto option like the E-Wide screen above. And while the i70 did alarm loudly, it also went into page Edit mode -- I don't know why -- and put up some random text in a big font. Ray's got some work to do here...
I tried two charting programs -- Coastal Explorer with the Em-Trak B100 on NMEA 2000 (like the MFD tests) and Nobeltec TimeZero Trident with the Vesper Watchmate on NMEA 0183 -- and while both showed the target, even with the correct icon in Nobeltec's case, neither treated it differently than any other AIS target and neither showed the SRM text. The same was true of the Garmin 7212 running 3.60 software from last fall. And while the update to 4.30 software did not cause my Garmin to shut down (or hopefully others around Camden), it also did not show the SART Test at all. Garmin realized that itself today and the techs in Newport started installing older software instead of the new version. They're definitely working on a real fix in Kansas, though.
But let's not forget that these AIS SART/MoB devices definitely can work with any AIS plotting device, and do to some degree with almost every one right now. It's just that the industry is just learning how to make best use of them as we learn what that might be.
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My Garmin AIS 600 transceiver has an pair of wires that can be wired to a switch and can be used to activate a distress signal. I haven't wired this yet but wonder if activated what shows up on the chartplotter screen? Is the distress notice located in the ships data when clicked on or is it much more apparent?
This is a feature that was original when the AIS 600 was first introduced.