"Børge Wedel Müller" wrote in news:4392f876$0
:

Could you "kick-start" me on the subject?


Look at the Google cache for the posts.

The sooner AIS is in all boats that can't turn quickly and must be in a
channel, the better.

This idea isn't "new". Ham radio operators have been using a GPS to VHF
or HF link called APRS, which is a much simpler protocol, for many years.

It was invented by Bob Bruninga, WB4APR, at the US Naval Academy to track
lost midshipmen in the Academy's small boats.
http://web.usna.navy.mil/~bruninga/aprs.html

http://www.aprs.net/
http://www.findu.com/ Let's you watch APRS from the internet
http://www.winaprs.org/

But, of course, this would be too cheap to put in a boat, no matter how
well it works. We have to have some outrageously-expensive, proprietary
system controlled by some patent holders, which really slows
implementation and leaves most small boaters unable to afford the
technology.

The AIS companies have live portals on the net to sell their wares:
http://www.aislive.com/AISLivePortal/
http://www.sealinks.net/World.htm
http://www.tsr-as.dk/ais.html even one in Denmark!
http://www.uais.org/LiveAIS.htm
http://www.dublinport.ie/
http://www.panbo.com/yae/archives/001018.html of course like charts,
we'll try to sell it to you.
http://www.lrfairplay.com/services/i...dvertising.htm
You'll need to have spam on the webpage, of course.

Just the ability to see around-the-bend in the river is worth having at
least an AIS receiver aboard. But, he won't see YOU unless you get a
full transponder.

Small boats at sea have always been at risk because, even with their
radar reflectors, they are such a tiny target, so low to the sea clutter,
most ships cannot see them, especially in close to the ship where the
ship's radar shoots right over the top of their masts when it's needed
most. AIS transponding completely solves this problem. The ship has a
constant view of your position, course, speed, who you are, what you are
for the lookouts (if there are any), even if your small boat is in the
bottom of the troughs. It's an amazing leap forward in safety-at-sea,
but will make small boats even MORE dangerous as the ships' watches rely
more and more on the new AIS display in front of the helmsman. Unless
you conform and buy a transponder, with him staring at his computer
screen for a lookout, he'll drive right over you.

AIS as well as giving CPA and TCPA does give the name and call sign of the
ship. This allows the sailer the option of calling the ship by name on the
radio which is more likely to get a answer. It also gives a much bigger
window to take evasive action. Line of sight from a mast mounted VHF antenna
on the sailboat to the antenna on a Deepsea ship is a great distance. My
guess is you will *see* anything within 40-50 miles. Thats close to a couple
of hours notice for the fastest containership.

BTW Panbo (http://www.panbo.com/yae/archives/cat_ais.html) is reporting
Class B AIS transponders for $500 (maybe).

SaltAir

"Larry" wrote in message
...
"Børge Wedel Müller" wrote in news:4392f876$0
:

Could you "kick-start" me on the subject?


Look at the Google cache for the posts.

The sooner AIS is in all boats that can't turn quickly and must be in a
channel, the better.

This idea isn't "new". Ham radio operators have been using a GPS to VHF
or HF link called APRS, which is a much simpler protocol, for many years.

It was invented by Bob Bruninga, WB4APR, at the US Naval Academy to track
lost midshipmen in the Academy's small boats.
http://web.usna.navy.mil/~bruninga/aprs.html

http://www.aprs.net/
http://www.findu.com/ Let's you watch APRS from the internet
http://www.winaprs.org/

But, of course, this would be too cheap to put in a boat, no matter how
well it works. We have to have some outrageously-expensive, proprietary
system controlled by some patent holders, which really slows
implementation and leaves most small boaters unable to afford the
technology.
....
If I remember correctly the AIS inventor , Håkan Lans, was forced to give up
his patent rights to get the system into the standards. I might be mixing it
it up with the corresponding system and standards for air traffic.
/Lars J

Just sailed up from Singapore to Langkawi via the Melaka Strait with
AIS running and found no buoys transmitting AIS data. Several base
stations are on the way but that is all.
Am running SR161 that gives a range of about 14 miles with the antennae
on top of the mizzen.
A very useful tool. Used it with the demo version of AIS-yacht which I
have found to be the most responsive and easiest to use and read.
Tony

"Lyn & Tony" wrote in
oups.com:

Several base
stations are on the way but that is all.


I think there are some misconceptions that to make a bouy show up on
everyone's AIS it needs to have a transmitter on it. This just isn't true.
ONE shore station with a tall tower can provide the AIS users with every
bouy, every obstruction or any other type of warning from its data stream.
It doesn't matter where its antenna is. This ISN'T some kind of radar
system, it just looks that way on the display. To show up, any object
needs data transmitted in range of your receiver from anyplace. The data,
not the transmitter's location, determines where the object is displayed.

Larry, true, this is one method of transmitting AIS data for floating objects. As far as buoys are concerned, AIS provides the possibility to allow them to transmit themselves or remotely from a basestation. Self-transmitting is normally used when environmental data is also transmitted.

I quote from the AIS specifications:
"There are three categories of Aids to Navigation in the AIS system:

Real AtoN: The AtoN is equipped with an AIS Station designed to generate
the appropriate AIS messages using local data from the aid and transmitting it via VHF.

Synthetic AtoN: The AIS message for the AtoN is transmitted from another
location (normally a base station) and the AtoN is physically located at the position given in the
AIS message.

Virtual AtoN:The AIS message is an aids to navigation message but no real aid exists at
the location indicated in the AIS message.


Holger

Holger wrote in
:

Self-transmitting is normally used when environmental data is also
transmitted.


Oh, wouldn't THAT be nice if all the NOAA offshore bouys and fixed stations
transmitted their data on AIS.....so you could see live how the wind and
waves are doing up ahead.

Other than realtime data, I see no reason to risk a radio system on a bouy.

"Larry" wrote...
Holger wrote

Self-transmitting is normally used when environmental data is also
transmitted.


Oh, wouldn't THAT be nice if all the NOAA offshore bouys and fixed
stations
transmitted their data on AIS.....so you could see live how the wind and
waves are doing up ahead.

Other than realtime data, I see no reason to risk a radio system on a
bouy.


I believe that you can get NOAA weather bouy data via XM satellite radio
today:

Here is more info on signing up for XM satellite weather.
http://www.xmradio.com/weather/
http://www.xmradio.com/weather/av_subscription_pkg.pdf

Go here http://www.xmradio.com/weather/marine.html and click on "Bouy
data".
"Buoy observations are taken from marine buoys and coastal observation
stations to determine wind speed, direction and gusts; air and sea surface
temperature; dewpoint; sea level pressure; wave height, period and
direction; visibility; pressure tendency and tide change. Data Broadcast
Frequency: 12 minutes"

Here some examples of two Garmin GPS units that receive and display XM
satellite weather data:

http://www.garmin.com/products/gpsmap376c/
http://www.garmin.com/products/sp2730/

www.tvnav.com has the Garmin 376c for $805