"luc" wrote in news:1163465166.495131.5330
@e3g2000cwe.googlegroups.com:

A couple of weeks ago, I took a friend's boat to San Diego from Moss
Landing, and it had a new Raymarine radar and chartplotter. It worked
great, though my experience with radar is limited, by the time we got
to SD, I had a pretty good idea of the menus, and how the thing worked.



I know SD is a very busy place, visavis shipping. Another good idea,
even if you never consider a full transponder so YOU show up, is the new
AIS (Automatic Information System)receivers. In that fog, you would have
no trouble at all spotting all the AIS-equipped shipping, those monster
targets that insist on moving around, unlike a rock or bouy you can stay
away from. AIS lets you watch, and avoid the beasts that can just ruin
your cruise, with ease. There are several new AIS to NMEA receivers that
will plot the AIS targets right on your chartplotter, probably with
nothing more than a plotter firmware upgrade. If you'd like to see what
it can see and look at the plethora of data it can provide you, the best
place is the Irish Sea. Go to Liverpool's great:
http://www.aisliverpool.org.uk/index.php
Take a long look around. The site is live, now in realtime. Just move
your mouse over a target on any map, chart or satellite photo and you'll
read all about him. Click on him and it brings up each ship's personal
webpage with near-realtime photos, taken automatically the last time he
passed one of the AISlive cameras in Liverpool's harbor. It's an amazing
software.

Someday, America may even have similar software running and shore-based,
fixed obstacle AIS transmitters that will cause everyone's AIS to also
show the fixed targets we still have to look for on radar....(sigh)



Larry
--
My calendar must be wrong....
In all the stores, it's ALREADY Christmas!

Charlie Morgan wrote in news:bbnjl2t0gr9j3us1eb81f8rb0ifceg1tpk@
4ax.com:

US Military ships do not, and will not, have AIS.

CWM



Very soon, military ships will also be totally invisible on your little
radar, too! They already have a few....

As with the stealth aircraft, THEY are to watch out for YOU....

Larry
--
My calendar must be wrong....
In all the stores, it's ALREADY Christmas!

"Larry" wrote in message
...
Charlie Morgan wrote in news:bbnjl2t0gr9j3us1eb81f8rb0ifceg1tpk@
4ax.com:

US Military ships do not, and will not, have AIS.

CWM



Very soon, military ships will also be totally invisible on your little
radar, too! They already have a few....

As with the stealth aircraft, THEY are to watch out for YOU....

Larry


I suppose we could equip all the logs, deadheads and kayaks with AIS, but
just here in the Puget Sound, it would be fairly expensive. Radar rules!
(assuming 3' or better scanner, and scanner mounted fairly low on the mast)
Old Chief Lynn

"Lynn Coffelt" wrote in
:

I suppose we could equip all the logs, deadheads and kayaks with AIS,
but just here in the Puget Sound, it would be fairly expensive. Radar
rules! (assuming 3' or better scanner, and scanner mounted fairly low
on the mast) Old Chief Lynn


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
--
My calendar must be wrong....
In all the stores, it's ALREADY Christmas!

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

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?

WTF? My 4kw Raymarine setup sees kayaks with no trouble at all. That and
when there water's smooth it'll even pickup the occasional bird and, rarely,
a crab pot float.

I have worked on 25kw units for aircraft (California fish and game) that can
see seagulls at 3/4 mile and measure fishing nets floating in the water.
This is how they busted the commercial fishermen that put out more net than
they were allowed.
The Magic here was in the digital processing to filter out the noise.
You can ether use lots of power or lots of processing power, these days the
processing power is cheaper and safer.

"Lynn Coffelt" wrote in
:

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!)


Radar requires the target to be REFLECTIVE, not absorptive or transparent
to RF. That's what that funny ball hanging from the already reflective
metal mast is, it makes you more reflective. A wet, plastic boat with an
RF absorptive human isn't going to cut it. The seawater returns more
than that....

As to your AIS barb...YES! But, your concept of AIS being located on a
bouy is all wet, so to speak. AIS has no bearing on it being mounted ON
the object it reports. That transmitter can be anywhere, as long as it
is in VHF range of the receivers. Fixed objects and Notice to Mariners
objects only need one, central transmitter high enough to cover the
entire area. This transmitter broadcasts the data of all these objects
every X minutes, to the delight of every AIS-equipped boat in range.
That range can be substantial. The sooner this equipment is installed
and the CG forced, kicking and screaming, to maintain its database with
all the latest data, the better!

For instance, a report comes in from the "Lady Disaster" that there is a
new object gone aground on "Monster Bank" at X lat/Y long, and represents
a hazard to navigation. The broadcast noone listens to goes out on
Channel 22 and falls on deaf ears. Admit it, you don't listen to it when
you're out, do you? I thought not. Who the hell's got time to plot
these broadcasts? However, the duty watch at the CG base also enters the
new object into the AIS database the fixed area transmitter draws its
data from. The very next transmission cycle, the new object shows up on
ever AIS display/chartplotter within 50 miles of the TV tower the
transmitter is located on. You can easily see the new obstruction. It's
right there on your display at the helm.

The bouy tender has arrived to assess the situation at "Jim Island" found
to be shifting into the channel. Bouy 4C is nearly sitting on dry land
because of the current shift and they lift it out and service its
batteries, replacing a bad bulb in the bulb rack in the head. They
replace the bouy in a new position further out in the channel than it was
to mark a safe distance from the new beach Jim Island is building for the
kids to play on next spring. Job completed, the duty radioman pops up
his AIS update screen on the ship's computer and logs onto the local AIS
database, right from Jim Island. He pops up Bouy 4C's record and enters
the new lat/long of its new position, making a note on its comment
section of the building beach to warn AIS-equipped boats to be wary as it
is still building. INSTANTLY, on the next transmission 86 seconds later,
every AIS-equipped boat notices 4C move to its new location and can read
that comment if they click up the bouy on their AIS-enabled chartplotter.

How long would it currently take to note 4C has moved 300 yards into the
channel, or a new warning come out from any authority now in use? Weeks?
Months? 12 days after the damned bouy has to be moved again?!

The sooner the better. There is NO TRANSMITTER ON ANY BOUY on an AIS
system! Totally unnecessary. There needs to be a central database and
high transmitter to cover the whole area on the AIS system... AIS is
about DATA, not direction finding.

Larry
--
Wow. Halloween candy has gotten cheap, lately!

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
--
add a 2 before @

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

I just knew that I would be "topped" if Bruce ever came onto this
thread. I think I might have worked on that first KRA124 of yours. There
weren't too many of them around here. The one that gave me more grief than
any I ever worked on was one on a well-to-do fisherman's yacht/halibut boat.
There were some strange diodes in the klystron tune regulated voltage source
that were no longer available (this in about maybe 1978). Dumb thing would
drift out of front panel tuning range periodically. Could bring it right
back with chassis pot, of course, but owner frowned on that and I never did
get paid! Don't blame him a bit.
We (Whatcom Marine/ Nordic Marine/ Anacortes Marine) took the
Washington State Ferries contract for a few years, and there were a few
KRA-448's that Northern had installed earlier. Super seagull radar with the
6ft scanner, but with the shorter scanner and all that power, it made nearby
ships real scary! Sort of wrapped around you! I think it was Northern that
put the 72 mile switch position modification on a couple. Only long targets
around here were from out in Rosario Straits looking north up into Canada.
Saw stuff to 62 or 63 miles if there wasn't any rain in the way.
AIS sure sounds great, but there is no substitute for radar (not
talking about the 3ft or less PCB antenna types). Some of the newer video
processing that cleans up sea clutter just has to be seen to be believed.
But I digress. Again.
Old Chief Lynn