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  #21   Report Post  
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Bruce in Alaska
 
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In article ,
"Steve Lusardi" wrote:

The Furuno is a fairly inexpensive RADAR and yet according to you, it is
doing
nearly impossible things.


Joe,
You are correct, it does, but it's good if it can. 80 nano sec. is quick.
Many of the commercial sets cannot.
Steve


80 nanoseconds isn't all that quick, in Xband, with SolidState Receiver
Frontends, Ring Circulators instead of the old T/R Cells of yesteryear,
and SolidState Modulator Strings instead of the old 2E25 Tube modulators
of yesteryear. Third and fourth generation commerical marine radars, have
been doing this good, for at least 20 years. What many "commercial sets"
can't do, is overcome the cheap design tradeoffs that most OEM's have
made to keep their equipment affordable to the guy who only runs his
yatch once or twice a year. If you pay the price for a good marine
radar, you will get the preformance that your looking for. If not
you will get what the Yatch Club Crowd, thinks they should have to pay.
$5kUS buys a reasonable marine radar, and $10KUS buys you what you
really want, but can't justify to the MRS....... Commercial Operators
buy the later........


Bruce in alaska
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Wayne.B
 
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On Fri, 06 Jan 2006 20:41:10 GMT, Bruce in Alaska
wrote:

Of course you have to remember that the KR-124 was a true 9Kw radar,
with a real good slotline 3Ft antenna, an excellent Logrythmic
IF Strip, and brand new 1N415E Crystals.


Good story. My Furuno is a fairly ordinary consumer grade Navnet
model but we pick up birds all the time on the close in ranges. Not
sure about styrofoam cups but wooden row boats are no problem.

No service required in the first year even though I installed it
myself. We're happy.

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Larry
 
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Wayne.B wrote in
:

And that will tell you about the 16 ft Boston Whaler fishing in the
fog bank right in front of you?



No, and neither will the radar scanner at 55 ft as some suggest to get long
range. Boston Whalers with little metal are hard to detect.

Of course, if we were to make $99 AIS transponders MANDATORY, problem
solved.

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Wayne.B
 
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On Fri, 06 Jan 2006 23:38:05 -0500, Larry wrote:

No, and neither will the radar scanner at 55 ft as some suggest to get long
range. Boston Whalers with little metal are hard to detect.


======================================

We have no problem picking up small boats with the scanner at 24 ft.

It is unlikely that mandatory AIS will ever become a reality for boats
under 30 ft or so, perhaps even larger.

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DSK
 
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No, and neither will the radar scanner at 55 ft as some suggest to get long
range. Boston Whalers with little metal are hard to detect.





Wayne.B wrote:
We have no problem picking up small boats with the scanner at 24 ft.

It is unlikely that mandatory AIS will ever become a reality for boats
under 30 ft or so, perhaps even larger.


And if it is made mandatory for pleasure boats, how many
people will still not have it, or forget to turn it on, or
leave it broken?

DSK



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Brian Whatcott
 
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On Fri, 06 Jan 2006 20:41:10 GMT, Bruce in Alaska
wrote:

Ok, I feel a Furuno Story coming on....... Many years ago (1975) I
installed one of the first Furuno KR-124 Radars imported into the
US, on a 85' Yatch in Lake Union, Seattle, Washington. This vessel
had a Professional Skipper & Crew. (ex coastie) Takes about 3 hours
if the antenna, and display are already mounted, and the interconnect
cable is already run but not terminated. Skipper was a sharpeyed older
gent, who wasn't sure that this kid,( myself) knew anything about
"Anything", and was determined to keep an eye on the whole process.
Got everything connected and fired up the radar, to do the Sea Trial,
and get the Heading Flash Reed Switch set to ships head. Nice clear
amazing picture on that analog display. As we were pulling away from the
dock, the skipper looks at the display and asks, "What is all that
clutter, down here in the port quadrant at .25 miles?". I look, and see
a bunch of targets, close together, and then look out with a set of
Binocs, and see a small group of Seagulls sitting on the water. "It is
that group of Gull's over there" says I. He says, "Bull ****". "No",
says I, "Wait till that seaplane taxi's over there, and they all take
flight, and the targets will all disappear of the scope". Sure enough
the Seaplane taxi's right thru the group, and all the targets disappear
from the scope except one. "Look, see they all disapperaed, just like I
said" skipper looks in the scope and says, "Nope, kid there is still one
target there". "Well", says I, "There MUST be something in the water,
over there". Skipper says "Bull ****, I can't see anything there with
these glasses, but we'll just cruise on over and look." So we idle on
over, and sure enough, here is a styrofoam cup floating in the water.
We pick it up, ad set course for the Can, right off GasWorks Park to
use as a Heading Flash setup target, and sure enough when we get .25
Miles from where the cup was, the skipper checks the scope and no more
target. "Hell, that is one great Radar to be able to pick up a strofoam
cup at a quarter mile. Never had that kind of luck with any of my
Raytheon Radars". I just smiled.........

Of course you have to remember that the KR-124 was a true 9Kw radar,
with a real good slotline 3Ft antenna, an excellent Logrythmic
IF Strip, and brand new 1N415E Crystals. When compared to what was
out in the fleet at the time, (Raytheon 1500's,1700's 1900's and Decca
101's and 202's) this was an order of magnitude leap in commercial
radar technology. And it didn't require ANY service for years at a
time, which really made the semi-monthly Raytheon Service look BAD.
That radar and it's follow on KR-248, and KR-448 is what MADE the Furuno
Name in the High Seas Fishing Fleets and North Pacific Coastal Freight
Fleets.

Bruce in alaska



Thanks for sharing that fun story - it must be a rare
bird - a radar story.....

Brian Whatcott Altus OK
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Gary
 
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Wayne.B wrote:
On Fri, 06 Jan 2006 23:38:05 -0500, Larry wrote:


No, and neither will the radar scanner at 55 ft as some suggest to get long
range. Boston Whalers with little metal are hard to detect.



======================================

We have no problem picking up small boats with the scanner at 24 ft.

It is unlikely that mandatory AIS will ever become a reality for boats
under 30 ft or so, perhaps even larger.

It won't be mandatory for everything. Kayaks, 14' alu boats, logs.
Radar is still better.

Gaz
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rick
 
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i am reminded of the guy with an early handheld plotting GPS walking around
in ten foot circles saying, "look, it tracks me exactly".....pre SA! I am a
relative newcomer to radar and use a digital RADAR-PC setup and during the
day i can imagine i am seeing all manner of things that show up on my
screen...if it is flat calm and the gain is high enough and the sewa clutter
is OFF....but at night in the fog healed 20Deg that dot that appears for one
scan...then mis and then two scans again then gone will have you staring at
the screen instead of looking ahead to see if it is a contact or a wave or a
ghost reflection from your rigging or even the bouy at 90degrees from the
blip. What about sidelobe reflections which are again reflected and
recieved...they are only interpretable after the fact...not a priori..? they
are lower in intensity and can look like a small contact in any place. The
receiver knows only when it switched from transmit to receive [time] and the
radial angle of the antenae at that time so a reflected signal appears only
to have been recieved from a distance equivelent to the total pathlength and
in a direction in a straight line perp to the face of the antenae at that
moment of capture...a ghost image. Then when you get a circular series of
large contacts you may well wonder what semi circular beast is ahead of
you.... read a book about the propagation of radar microwaves and see all
the ways a blip can mislead you and thank God the guy you almost mowed over
didn;t have radar and was keeping a lookout. Radar assisted collision are a
significant reality. Real life radar is a tool that must be interpreted and
i am finding out it takes a LOT of interpretation and experience to be able
to rely on it more so than your eyes. The mainbang is suppressed so you
don;t see the big donut around your boat extending for 200ft on a 1/2 mile
range...if you are at 1/8th mile you might see a target at 50ft but only if
the mainbang is not supressed and the gain turned way down and the sea
clutter way up to exponentially deminish the gain applied to close returns.
As for styrofoam cups....the intensity of an electromagnetic wave falls off
in a cubic [3rd power] manner relative to distance and the reflected wave
similarly diminishes but the part reflected is only that portion perfectly
perpendicular to the antenae...as it dips and turns on a weaving mast even
less of it is oriented in a 'perfect' manner. The intensity of the emmitted
electromagnetic field recieived by the antenna is so small it is a marvel
that modern electronics can even discriminate it from the background noise.

Now the clincher....what portion on the emitted signal would a round
styrofoam cup reflect from half amile away? hint, styrofoam is not a
reflector of electromagnetic energy..is it an insulator and absorbs
microwave energy. the only reflection would be from moisture in a thin
lhorizontal line...perpendicular to the antena and the relfected signal is
likely a billionth of the emmitted signal at best. Granted there are
galenium arsenide semiconductor equiped ultra low noise receivers that could
discriminate that SNR but at a few thousand dollars in the hands of a
relatively untrained operator the pleasure boat operators radar.....it makes
for good bench racing stories but little more. AND...if you really are
detecting the water on a birds wings i suggest you tune and adjust the radar
to pick up and discriminate larger targets...else they will be lost in the
clutter
In the process of ruining a 'story' i hope to have saved someones life by
stimulating you to really learn what a radar can and can't do...repeatably.
Quod erat...you know the rest of the story.
rick

"DSK" wrote in message
...
No, and neither will the radar scanner at 55 ft as some suggest to get
long range. Boston Whalers with little metal are hard to detect.





Wayne.B wrote:
We have no problem picking up small boats with the scanner at 24 ft.

It is unlikely that mandatory AIS will ever become a reality for boats
under 30 ft or so, perhaps even larger.


And if it is made mandatory for pleasure boats, how many people will still
not have it, or forget to turn it on, or leave it broken?

DSK



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