In article ,
"Lynn Coffelt" wrote:

Your radar can see logs and kayaks?! I want one of those! It's gotta be
magic. How many gigawatts does that take to get a return off a plastic
kayak?

I guess you're assuming the guy in the kayak has a metal Coleman stove in
there, too...(c;

We border on the absurd....which is why they'll make them mandatory over X
ft long....and all that go to sea.


Larry

Gigawatts? Woohoo..... we don't want to burn the hair off the poor
guy's legs, just see a wee echo from the fillings in his teeth! Seriously, a
3kw with a weak maggie should be able to see seagulls and ducks on the water
(when the water is flat, of course). I don't have a radar at all, but have
worked on thousands of them. Well, OK, maybe only hundreds. When the short
range, X band radar scanner is fairly close to the water, as opposed to the
mistake of mounting as high as possible, painting small wet objects improves
greatly. I'm sure many are familiar with the impossible sea clutter one
encounters looking down at a high angle from high up on the ship. Painting
any targets at all is a challenge. Oh, yes, it sees those mountain ranges 30
miles away alright, but we aren't apt to hit them soon.
Is AIS used on relatively unmovable objects such as rocks and small
islands? There are quite a few radar beacons in use, but some radar receiver
interference rejection schemes wipe them off the screen too. (I almost said
"scope", nearly revealing my age!)
Christmas? I thought we now used politically correct names?
Old Chief Lynn



Ok I feel a "Story" coming on..... Years ago when I worked for Northern
Radio Company in Seattle, WA as a Field Tech, they picked up the Furuno
Radar Line, and sold the first KRA124 in the country. I was the Install
Tech, and we put it on a "Big Time Pleasure Cruiser" floating in Lake
Union. Antenna unit was 9Kw (2J42 Magnitron) with a 3 Ft Slotline,
Endfeed Antenna, and a Linear IF Strip. When we were out on Sea Trials,
setting the Heading Flash, and Tx Pulse Delay, the skipper noticed a
bunch of target returns about 1.25 miles off the bow. He looked out with
some Binocs and couldn't see anything that looked like a Radar Reflector,
so he asks what those targets were. I took the binocs, and scanned the
area, where the targets were on the scope and there were a small flock
of seagulls, sitting on the water. "Seagulls" says I. He said "BS" and
I looked again, and said "Wana Bet?" He says "Sure, how much can you
afford?" "Lunch at the Latitude 48 would be nice", says I, and we had a
bet. Just then, a SuperCub on floats was taxiing out from Kutzner Air
Service and headed for the Seagulls, so I told him to watch the scope,
and as soon as the floatplane got close to the birds, they would fly
off, and all the targets would be gone. Sure enough, the SeaGulls flew
off, the floatplane took-off, but the Skipper says "There is still a
target there". I look in the scope and sure enough there is still one
target in that spot. So I says, "There is something there, but it is to
small to see at this distance." He says, "BS, but we will go over there
and take a look". So we cruise on over and sure enough, there is a
styrofoam coffee cup floating in that location. He has the Deckhand fish
it out of the water and we head on back to the dock. Sure enough, "No
More Targets in that part of the lake. I got my lunch, the Skipper got a
Great Radar, and we both have a Great Story to tell for the rest of time.

Nothing like 9Kw of XBand RF with a Good Slotline Antenna to pick up
small stuff on flat water. These 4Kw T/R Pans just don't have the
poop, even with the new LogRythemic Receivers, and MMIC's for Frontends.
All it takes is Power, and a decent antenna, which are in short supply
on most non-commercial and Pleasure Craft type Radars these days. That
same 9Kw T/R with a 6Ft antenna was the basis of the KRA-448 Furuno
Radar that was a 48 Mile that could see out to 72 miles if you pushed
it. Mountains that are 6000 ft tall show up real well, at 72 miles.

Bruce in alaska
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