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In article .com,
wrote:

Bruce,

Jeez ... you oughta teach ...

Recreational boat, height say 12 feet ... would making a change in the
angle of the radome be wise? In other words, would it make sense it to
have a unit that
could be maneuvered up and down (up being level, down being a degree or
two difference from ideal)?

For that matter, would "up" increase range (obviously losing minimum
read)?

Gary

Gary,
I do teach, and have taught many a budding Marine Electronics Techs,
as well as Commercial Operators and Skippers, for many years.

Changing the Pitch of the Antenna is only slightly effective, in lowering
a radars MRR. This is due to the Vertical Beamwidth being 25 or
so degrees. This beamwidth is expressed at the -3db points (Half Power)
of the Main Lobe of the Antenna Pattern. so moving it just a coule of
degrees isn't going to have a significant effect on MRR.

The Largest Factor, that can be adjusted for, in MRR, is RGD (Receiver
Gate Delay) and this is usually set via an internal control at
installation. If it is set to short, Close in targets will curve in
toward the center of the display on the Shortest Range. If it is set to
long, then close in targets will bow out from the center of the display
on the Shortest Range. It is a very small adjustment of only a few
microseconds, one way or the other.
This adjustment is required because the designer can't know how long the
interconnect cable between the Display and the RF Deck is going to be
in any installation and it must therefor be adjusted AFTER the cable is
installed, and cut for length, if nessesary. Some of the later models
of consumer radars, don't allow for the interconnect cable length to be
changed, and therefor the Factory Setting is good enough, but if the
installation requires ANY change in interconnect cable length, then the
RGD setting must be recalibrated for proper operation, as specified in
most installation and user manuals.

Years ago we installed an Xband Furuno Radar on the ForeMast of 260 Ft
Reseach vessel, that had an AftHouse design. This allowed the new Radar
to have a clear, unobstructed, view forward, so as to allow the best
possible sensitivity for seeing small Research Bouys at the langest
ranges. The interconnect cable was 5 or 6 times as long as what the
designers intended, and we had the Factory help us install a modification
of the RGD system to take that fact into account, during installation.

Bruce in alaska
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