AIS hp -528A with STandard Horizon 300i

[KAM]

All working well independently but when AIS is connected to the plotter I can see the AIS data but when using track function on the autopilot after a few minutes the waypoint jumps. This morning were heading for Colonsay but waypoint keeps jumping to the Ivory Coast. Normally I'd be happy with that but today it's taps aff weather and Colonsay will suit us just fine. Looks like I may need to cancel an NMEA sentence on the plotter but to save a lot of experimentation any pointers would be much appreciated.

 

[andsarkit]

Could be corruption of the NMEA data. Did it work previously or is this trying the track function for the first time?
Difficult to tell without a scope on the data stream but you could check all connections.
Are you using the same ground connection and power supply for all the instruments?
Are the cables screened and could you be getting interference from an echo sounder or alternator?

Edit: Check if there is a waypoint in the 528A that is conflicting with the waypoint in the SH300.

 

[KAM]

The systems been in for 12 years and was ok with a Digital Yacht AIS receiver. I just use telephone wire to connect so dont think its well screened but joints are soldered. I'll see if there's a waypoint conflict.

 

[KAM]

Thanks for the pointers. I had several waypoints set on the 528A so I'll see how removing them affects things. No traffic just now to test. One slightly odd thing was that I changed port 3 input on the CP300 from NMEA to GPS auto. This seemed to disable the NMEA to the VHF and android repeater despite being labelled as a CP 300 plotter input. It's a big problem when you only have to fiddle with things every 5 years or so.

 

[KAM]

No joy. The plotter also zooms out by itself.

 

[KAM]

No joy. The plotter also zooms out by itself.

In case it helps anyone else it turned out to be noise due to using telephone wire instead of proper screened cable. It had worked ok for 12 years. Took a long time to resolve as the boat needed to be moving with all the bits hanging out and wires exposed. It now doesent try to randomly route me to the Ivory Coast when on Track and the AIS data appears nicely on the CP300.