Realy very haevy trafic, here it is many times small than this. I think
this will be a big problem for AIS in the future anyway.

But, reading the NASA AIS radar user manual, I found that it has
several options to setup the equipment in addition to the range
settings.

AIS radar operation has several limitation like:

a) It can track up to 24 ships. If there is more, it displays only the
24 more proximity
b) Plots only the 16 last track points of each ship

NASA AIS radar can be customized by the user which can set the update
rate to 8, 15, 30 or 60 sec.

I believe that this limitations and controls can tune the operation in
regard to speed/power of the processor.

What do you think about? Maybe Garmin can include this setings in the
GpsMap276C AIS function. As you can see, I am crazy to use the AIS in
my boat, and I would acept any restrictions wich could be need to get
it on my Gpsmap276C.

Best Regards

Pascal

On 14 May 2005 06:31:15 -0700, "Pascal" wrote:

Realy very haevy trafic, here it is many times small than this.

Possibly, but it mightn't always be that way, and manufacturers who build
equipment for best case scenario instead of worst case won't last long
anyway.

AIS radar operation has several limitation like:

a) It can track up to 24 ships. If there is more, it displays only the
24 more proximity

Sounds dodgy to me - what if there are 24 stationary ships around you & 1
damn fast ferry coming straight at you? Will it swap over to the important
one quick enough for you to do anything about it?

NASA AIS radar can be customized by the user which can set the update
rate to 8, 15, 30 or 60 sec.

Too slow for real-life - AIS transmitters on boats going fast & turning fast
tx at 2 second intervals (1 second if in assigned mode & assigned to 1
second), so if you have your receiver set to 60 seconds then you could be run
over before you notice it.

I believe that this limitations and controls can tune the operation in
regard to speed/power of the processor.

Sounds to me more like they make it into a useless toy. AIS is specifically
designed for collision avoidance (though it has been hijacked for homeland
security) & a lot of thought has been put into how many ships should be
processed, how often boats should transmit, etc. All these limitations make
it dangerous if someone hooks up a NASA radar & thinks that this is going to
save them from having to keep a good watch.

What do you think about? Maybe Garmin can include this setings in the
GpsMap276C AIS function. As you can see, I am crazy to use the AIS in
my boat, and I would acept any restrictions wich could be need to get
it on my Gpsmap276C.

If you really wanted to do it, you could get an AIS receiver, hook in a
computer, re-code the AIS digital signals to DSC digital signals & feed to
the 276C. However, I don't think this is something that Garmin should be
tackling as - it takes a LOT of processor power, and how is AIS going to look
on such a small display anyway? It will be far too cluttered.

Here are some screen dumps from AIS around my area - as you can see, the
screens are fairly cluttered even on a 1024x768 screen.

http://www.jodael.com/sr162_performance_testing.htm

Cheapest solution for the moment is an old notebook, free software, and an
AIS receiver like the SR162 (or NASA engine though I prefer dual-channel
receiver). If you have a notebook lying around you could be up & running with
AIS display for US$300 or so.

Dave

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Thank You again Dave,

I have see the atached link document of the tests you had made, and
really, there is a lot o ships there.
I bacame very disapointed with your conclusion about the lack of
possibility of AIS in 276C. In relity I am very disapointed with my
Map276C. It has features I ado not use, like the automotive
routing/nav, the fishfinder function with the GSD20, wich I will never
would buy, the DSC function wich is useless, and with the problem os
lack some NMEA messages (BWC/XTE) wich cause me a big problem with the
autopilot, so I must use the old Map76 and Map130 for the AP.

If the Map276C could not have AIS as you said, so I will sell it and
buy another thing. I alredy have a old laptop and many chart ploter
programs and many charts, and maybe I must change my position about the
use of a PC in my boat.

Thank you for your advise and best regards

Pascal

On 14 May 2005 19:27:15 -0700, "Pascal" wrote:

If the Map276C could not have AIS as you said, so I will sell it and
buy another thing.

Note that I don't work from Garmin! :-)

I alredy have a old laptop and many chart ploter
programs and many charts, and maybe I must change my position about the
use of a PC in my boat.

Sounds like you have plenty of reason to use one, so with the addition of a
US$200 NASA or US$600 SR162 receiver you could have yourself a decent AIS
display.

Or wait a few months longer & AIS Class B transceivers will be out, and you
can display other boat positions on your PC while transmitting your own
position at the same time.

Dave

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Than You Dave,

Next week I will try a test with my laptop and the shipplotter software
using a small VHF wich has 87/88 channels and connection to my pc sound
input. The NASA could be a beter solution using the Sea Clear, but I
will wait my friend's test when his NASA engine arrives nex month,
before making a decision.

Besta Regards

Pascal