Globalsat BT-358 and SeaClear Problem

[gchabs]

Just bought a new Globalsat blue tooth GPS model BT-358. Have loaded Seaclear nav software on both a netbook and desktop. I also bought two bluetooth dongle's for the computers to communicate with the BT-358. When I start the GPS, Seaclear shows that I am connected to the GPS, but also shows my COG as random courses, ie. 300, 055, 280, etc., and my SOG as anywhere from .1 kts to 2.5 or more kts. These results are achieved even though I am standing perfectly still and not moving. Any thoughts? Any fixes? Thanks. George

[GordMay]

Greetings and welcome aboard the CF, George.

I think it’s simply marvellous how modern technology (of which I’m mostly ignorant) can transport a stationary individual at 2.5 or more kts.
Would that be akin to teleportation?

Seriously, I’m certain someone competent will offer some useful opinions and help.

[GPSNavX]

As soon as you actually move, the Globalsat GPS will provide accurate readings.

[brak]

This issue exists with most "hockey puck" GPS units I tested. What they really seem to produce is "momentary" speed and COG based on tiny random errors in reading satellite data. You probably noticed (or will) that the "speed" and COG changes are more pronounced when the device is indoors or otherwise has imperfect reception.

Incidentally, PolarCOM has specific functionality to dampen this "running in place" drift and keep SOG/COG more stable.