B&G AIS Tranceiver Not Transmitting

[Howler]

Hi, My B&G AIS 500 transceiver frequently stops transmitting. The cause appears to be loss of GPS position. I use the standard B&G GPS antenna, which has about 30 ft of RG174 cable. I’ve read that this cable can be very lossy, especially over 10 ft.

- Has anyone else experienced intermittent lost GPS position on their AIS 500?

- Is the point about the lossy cable accurate?

- If so, are there other compatible GPS antennae with better cable that would work here?

Thanks!

[fogmachine]

Have you tried hooking up a PC/Mac with the B&G "NAIS System Configurator" to the USB port?

[Howler]

Originally Posted by fogmachine

Have you tried hooking up a PC/Mac with the B&G "NAIS System Configurator" to the USB port?

Yes. And the error message shows "no GPS position" or something to that effect.

[Brian.D]

I guess the first question I have would be: has it worked before? And if so, what has changed for it to stop working?

Now, for the loss factor, @1GHz, the loss is 32dB/100ft. So you would be seeing 9.6dB loss over the 30 ft of cable. That is... if the antenna is sending the GPS signal at frequency. Now, since GPS frequencies are above the 1GHz frequency, there would be more loss. But... if the GPS receiver is using a down converter for baseband, it makes no difference since baseband is basically just a voltage. There could be some voltage loss in the data, but unknow.

Now this leads to the next question, if the GPS antenna is really a receiver is it getting the correct voltage to work. If not, then it is probable an issue with the AIS unit not sending the correct voltage, or the receiver is not getting the correct voltage. In either case, one should check to see if there is a voltage on the cable.

Finally, if you are getting the dreaded "no signal" (which it looks like you are) then remove, clean, and reinstall your connectors. We know that sea air is notorious for corrosion factors and it does not hurt to do general maintenance on all connectors.

As always, JMHO

[Brian.D]

One other thought occurred to me. It could be a configuration error on the part of the data stream from the GPS antenna. Check to see if by chance you can select different sentence structures from the GPS.