When I turn on my SSB radio, I hear what appears to be the NMEA
sentence being transmitted. It sounds kind of like morse code.
Disappears when I turn the GPS off. The GPS signal is being fed into
the SSB, the VHF, the navigation computer and the radar. This noise
doesn't appear anywhere else... any ideas?

"Keith" wrote in message
oups.com...
When I turn on my SSB radio, I hear what appears to be the NMEA
sentence being transmitted. It sounds kind of like morse code.
Disappears when I turn the GPS off. The GPS signal is being fed into
the SSB, the VHF, the navigation computer and the radar. This noise
doesn't appear anywhere else... any ideas?

Is the signal fed into the SSB, VHF, computer and radar directly from the
GPS or did you use a buffer/splitter?

If so, read a bit about single-ended and differential NMEA connections at
http://www.shipmodul.com/en/index.html

There is a good chance that a differential output of a splitter is connected
to a singe ended input (an input with ground). What happens then is that one
signal of the output is short-circuited to ground, resulting in high
currents, in turn producing harmonics up to the HF range.

Meindert

The cable comes from the GPS to a terminal strip, then from there to
the various instruments. I used a Noland Multiplexer once, but it
didn't seem to make any difference and actually seemed to harm the
signal, so I took it out.
I'll go check out the article you mentioned, thanks.
Meindert Sprang wrote:


Is the signal fed into the SSB, VHF, computer and radar directly from the
GPS or did you use a buffer/splitter?