I spoke with the tech at KVH (makers of the Azimuth 1000). There compass sends the signal at a 4800 baud, RS422 protocol. Even though I disconnected the compass once I started receiving check sum error warnings, I am still receiving these warnings. All I have connected now is a combo GPS/AIS antenna. Would like to add (again) that the system originally worked fine. Is there any chance your unit could be corrupted? Can I send it to you for a bench test?