GPS height ( was AIS pitfalls )
Hi John -
You make some good points; your statement copied below prompted me to think
about the GPS receiver in the Furuno 1943 radar. It is DGPS-capable and so we
use it for AIS and CE as well as the built-in ARPA.
My thoughts revolve around the fact that the ARPA targets' headings often
vary wildly in a seaway and especially at longer distances, although they do
settle down closer in. I'm thinking that the height (24 feet) may be the cause.
Although I haven't studied it, a glance at the menu tells me I can't defeat
the internal GPS and source the data input for ARPA externally from a unit
mounted lower. I'm curious why you say, "the dome for that is mounted high
above everything else at about 38' elevation to make it work well," when
conventional wisdom is to mount them as low as possible to avoid "swing."
Regards,
John
"Seahorse"
To your other point, for course input, we do have a GPS compass
system... the dome for that is mounted high above everything else at
about 38' elevation to make it work well. I understand it uses 3
GPS's all by itself. It broadcasts heading to all devices on our NMEA
bus. It worked great coming up the Pacific coast from Dana Point to
Victoria, BC, even in large, steep head seas when we were pitching
like crazy. The swing at 38' above the water must have been dramatic.
************************************** See what's free at http://www.aol.com.
Snip
I'm curious why you say, "the dome for that is mounted high
above everything else at about 38' elevation to make it work well,"
when
conventional wisdom is to mount them as low as possible to avoid
"swing."
End Snip
What you say is correct, maybe he was trying overcome what I realize
as a shortcoming in my design. When I was having my electronics
installed I attempted to have as much installed on my mast as
possible and as few holes as possible in my Pilot House. Later is
when I realized that Furuno asked that the GPS Antennas not be in the
path of the radar I did a quick test looking at my signal strength.
With the radar on I would lose my connection to about two birds and
watch the signal strength drop on a couple of others. Maybe if I can
find some gadgets to fill those holes later the Antenna's will be
moved to a more appropriate place. :-)
John Ford
KK44 Feisty Lady
Annapolis City Marina
Mr. Ford,
May I suggest a FLIR as a nice gadget to fill a hole?
Regards,
Dan
-----Original Message-----
From: passagemaking-under-power-bounces@lists.samurai.com
[mailto:passagemaking-under-power-bounces@lists.samurai.com] On Behalf Of
John Ford
Sent: Tuesday, June 05, 2007 5:34 PM
To: Passagemaking Under Power List
Subject: Re: [PUP] GPS height ( was AIS pitfalls )
Snip
I'm curious why you say, "the dome for that is mounted high
above everything else at about 38' elevation to make it work well,"
when
conventional wisdom is to mount them as low as possible to avoid
"swing."
End Snip
What you say is correct, maybe he was trying overcome what I realize
as a shortcoming in my design. When I was having my electronics
installed I attempted to have as much installed on my mast as
possible and as few holes as possible in my Pilot House. Later is
when I realized that Furuno asked that the GPS Antennas not be in the
path of the radar I did a quick test looking at my signal strength.
With the radar on I would lose my connection to about two birds and
watch the signal strength drop on a couple of others. Maybe if I can
find some gadgets to fill those holes later the Antenna's will be
moved to a more appropriate place. :-)
John Ford
KK44 Feisty Lady
Annapolis City Marina
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