"Doug" wrote in message
news

"BOEING377" wrote in message
...
When will GPS compasses come down in price? Just came from the bridge of
an APL
container ship where they had two Sperry GPS compasses. They have
replaced
mech
gyros on many ships and are very accurate and responsive. Cost about
$17,000.00
each.

Furuno makes GPS compasses is the $ 5-8K range. A GPS compass is an
entirely
different critter from the NMEA compass information provided from a GPS
sensor. A GPS compass is not using the datastream. It is using three
antennas at least and doing carrier signal phase difference measurements.
A
proper installation requires a technician who understand radio wave
reflections, and even he may have to reposition the antenna array a few
times for proper results. It is really trial and error at first. I know of
two identical 80 foot Alaska crab fleet boats, where one system works
super
and the other is still fighting problems. And, yes, they provide Furuno
AD-10 format compass data to a radar. A diagnostic program may take 12
hours
to run for results.

Doug K7ABX



KVH has one for around $3k. Have not seen it in use.