On Jan 29, 10:14 pm, larry wrote:

GPS is an analog system of precisely timed pulses, not unlike Loran C

Fascinating post - regarding the inherent fallibility of GPS
technology. That was a really good read - thanks.

Prior to installing the Raymarine GPS, I've been using a Garmin GPS III
+ connected through a USB to serial connector into a laptop. I've
never seen this type of behavior on the Garmin - but then again, the
external antenna which I used on the Garmin was well away from any
metal.

The Raymarine is mounted on my brand new radar arch, about 6" away
from an external Wi-Fi antenna and 4' away from the Raydome. I don't
use the Wi-Fi antenna when I'm underway, and it's only about 1"
diameter x 30" tall, so I'm not sure if that creates enough of a
shadow to cause the problems. Here is a photo of the setup:

http://anon.org/images/arch.jpg

This photo was shot during the 2 months that Raymarine was replacing
my E120's motherboard - so all you can see of the GPS is the white
plastic bag covering the base - but it should give you an idea as to
what the install looks like.


By the way, Seatalk isn't rocket science. Connect Seatalk data wire

Another exceedingly helpful thought. I'll certainly give it a try.

cognisense wrote in news:740a6e0f-ada6-4979-a3ec-
:

Another exceedingly helpful thought. I'll certainly give it a try.



AHA! Now we're getting somewhere!

Put the radar in standby and see if the position jumping stops....

Move the GPS off the arch and just sit it on the helm away from
everything for a test trip. (Any excuse to go boating is greeeeeeat.)

My bet is the jumping stops when you shut off the radar transmitter
trashing it.

GPS has no need of altitude. Both ours are in a cabinet over the galley
sink inside the boat with clear RF view of the sky. It only moves when
USAF C-17 fly over us...the aluminum cloud.

Lets get the GPS away from the radar noise source.