Vesper Marine AIS Integrity Test

[David Grimm]

Anyone encounter this notification on their Vesper Marine AIS Watchmate? The unit had been on for about 7 days straight and I was 25 miles off the coast of nyc at the time of this message.

It appears to work normally. I tried calling Vesper to find out they were brought out by Garmin. I'm planning a trip to Nova Scotia this summer and this was on my check list.

 

[Christian Williams]

Don't really know, but I have the same unit and have received similar messages.

I figure it has to do with satellite lock and triangulation and such, and resolves after a time.

I have experienced complete loss of signal for an hour or more, with some message such as "searching for satellites" or more dire "comm lost!" etc. It always comes back, but of course in the meantime....

Fellow member Ignacio and I both noticed odd GPS behavior and loss of Vesper signal when sailing past the Vandenberg AFB Space Launch facility just north of Point Conception. I call that a "military coincidence."

 

[David Grimm]

Christian, Thank you for the rapid responce. I personally never saw mine glitch before. I now feel somewhat reassured and will take it off the list of things to worry about!

 

[Kenneth K]

GPS by itself isn't reliable enough for most aviation purposes; there are known and predictable degradations to its accuracy and availability. So, aircraft GPS Receivers are augmented with Autonomous Integrity Monitoring (RAIM) while the GPS signals they receive are augmented by Ground-Based (GBAS) and/or Space-Based Augmentation Systems (SBAS/WAAS). Without any similar systems, perhaps the best a Vesper or similar device can tell you is "signal lost" when it gets downgraded GPS information.

Perhaps some more interesting reading here: https://en.wikipedia.org/wiki/Receiver_autonomous_integrity_monitoring
For example, "To obtain a 3D position solution, at least four [satellites] are required. To detect a fault, at least 5 are required, and to isolate and exclude a fault, at least six are required, however often more measurements are needed depending on the satellite geometry. Typically there are seven to 12 satellites in view."

And,

https://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/techops/navservices/gnss

Click through the navigation bars on the left for topics: GPS, GBAS, WAAS, etc.