Losing GPS Signal

There are tables and lots of built in thingies that we will never understand.

Turn it on and leave it on for a day or two.
If the latest tables do not down load, you may need a software update.
These updates usually come thru the Simrad MFD when it is connected to the web. All needs to be powered on for a while for this also.

Are you sure it's "just" an antenna?
I mean, old plotters used to rely on a passive antenna, typically connected with a coaxial cable, but the GPS "intelligence" was inside the plotter itself.
But nowadays, most of what we are used to call GPS antennas are actually self-contained GPS units, that directly transmit the converted signal to the plotter via NMEA cables.
If as I would guess you've got the latter, in the worst case you can simply buy another one and swap it. No need to find an identical one, any of them should work.
And they are reasonably cheap, these days...

The GPS signal loss could also be a function of some other data stream corruption. My Ray system GPS antenna has an indicator light on it, and glowing red tells me that the antenna is locked up, requiring a reset. If I have such an error and the light it green, the problem is in the backbone. Another means of hunting down the issue is to fully isolate your entire network of gear with power only to the backbone and plotter, all other gear off. If no error occurs the conflict is in the backbone brought by another device. If the error still occurs, the issue is most likely within the GPS antenna.

My system when fully up and running (lots of gadgets) throws a GPS error when I power up one of my VHF radios. The error clears, but it flashes as the VHF is coming online. Much data leads to sensitive chains subject to glitches.

even though nothing changed, that doesn’t mean something didn’t change, so to speak. The concept was to isolate the GPS and test it in a bubble. Eliminate all other variables. I’ve had random issues that were later identified as a bad cable or a bad network switch. Once it happened as I left the yard and after batteries had been off for two weeks.

Very good catch, I hope. Chasing these gremlins can be a PITA.

My terminology of "antenna" may of just been short. Most of the time the antenna is the active all-in-one assembly including the processor.
Even if it is just a bump on top of a Simrad display.

I still have a back-up RayNav 310 that uses a passive antenna (1" square etch at the end of a coax).

Still, the processor (wherever it is) receives tables, telemetry, clock cycles and more to help it time itself with the best satellites and calculate your location.
After such a quick change in location, different satellites are in use and all this new data must be loaded before a reliable operation can begin.
And you need continuous view of a few satellites to load this info that may take several minutes to a day.


I recall the EVO3 has a built in wifi also. If no internet around you, set your cell phone up as a hot spot and let your Simrad connect to it.

Interesting. Do you mean that you have 2 GPS mushrooms, both sending a separate GPS signal on the same N2K network, and you can select either one or the other independently from each plotter?
I would have thought that such configuration can't even work, due to two different GPS sentences conflicting on the same network.
Or maybe it's a Simrad-specific feature?
Just curious.