"Pascal" wrote in message
oups.com...
Ok Jeff,
I agree that the distress function of the RADIO using DSC is important,
but for this, any gps can send the position of my boat to the radio, so
that the mayday buttom works. I was saying that the polling function of
the radio, for position report on my gpsmap276c is much less usefull
than a AIS function. The position report can tell me the position of
others boat only when ruested by the polling function, so I must know
the mssi code of the boat; I think this can be usefull to a flotilla
cruising or maybe to fishing boats, or a race comitee. To have the
position of a mayday boat in the gps ploter is not so usefull, because
it is rare fact, and a sailboat or any leisure boat has little to do an
a mayday function, contrary to ships or CG duties. The AIS main value
from a sailboat perspective is Colision avoidance, and in this regard,
a AIS transponder with a AIS receiver would be better, but a AIS
receiver only would be vey usefull .

Concluding, I think that the ideal solution would be a VHF/DSC/AIS
ready radio, wich could receive the AIS signal of all ships for
colision avoidance using litlle 12 V charge, but in a danger situation,
I could activate the transmit function to send automactic to all ships
my position (uses more 12V). The AIS NMEA message received could be
send to my Gps/Ploter wich would plots the ships position etc, like
others softwares does (ShipPloting, SeaClear, MaxSea, SeaPro etc), and
providing other important information like CPA/TCPA etc.

Regards

Pascal

IMO will not allow AIS and ARPA on the same screen, so some larger
commercial radar displays now are on the market with a switch to toggle
between ARPA and AIS. These same units sometimes are sometimes available for
non-IMO vessels allowing simultaneous ARPA and AIS on the screen. Adding DSC
on the same screen would probably not be a smart idea due to clutter.
Putting it on a separate chart plotter that polls the DSC VHF and HF radios
sounds better to me.
73
Doug K7ABX

Thank You all,

We here (Salvador/BA-Brazil) are trying to understand a bit more about
AIS. I have instaled the Sea Clear free program and I was surprised to
see that it is a very good program, suporting AIS and using the
G7ToWin for download/upload, can use BSB and scanned charts (we have
the OziExplorer from many years).

A friend here had instaled the Ship Plotter demo software and made a
test with his Icom Ham Radio and it worked very well: he gets about 20
ships here in Salvador/BA using a VHF antena instaled in the roof of
his apartment building (very high) and plotted ships up to 20 nm from
his home.

The Ship Plotter sends information to Ozi (we do not know how)
wich displays the ships as Map Features. We are having trouble in
making it works with a standard marine VHF reciever, so he is buying a
NASA black box Receiver for his boat and will use it with his laptop
and Sea Clear.

In my turn, I have a laptop too, with several othres navigation
softwares but I think that it is a cumbersome thing in my boat, so I am
waiting that Garmin unveils soon the AIS function for my GpsMap276C, or
I will buy the NASA stand alone AIS.

If the NASA with display would have a NMEA out interface too, like the
black box model, so I could use it as well with the laptop too, I
would have already buy it now.

In another forum (discution list) someone made the folowing coment to
my entry:

" Then I think you schould start reading again."
"All DCS capable Garmin receivers are also AIS capable.
DCS is still the most wideley spread system, and AIS does not add
anything to Garmin GPS receivers over the DCS system."
"You can easely combine a Garmin with DCS with a AIS reciever since the

data send to the (external) gps is exactly the same."


This make me think that, maybe Garmin is developing the 3006/3010/276C
software for AIS support and the Garmin Network could receive another
Garmin "sensor" member: a black box AIS receiver wich could be a AIS
receiver only (GAR20?) for the poor and a AIS receiver/transponder
(GAR40?) for the rich.

Off course, this is my pure speculation, and dream ...

Regards

Pascal
S 13 00/W 038 27

On 13 May 2005 17:29:21 -0700, "Pascal" wrote:

In my turn, I have a laptop too, with several othres navigation
softwares but I think that it is a cumbersome thing in my boat, so I am
waiting that Garmin unveils soon the AIS function for my GpsMap276C, or
I will buy the NASA stand alone AIS.

Personally I doubt that you will see AIS for the 276C. Where I live there are
often hundreds of vessels within AIS range, so we are talking a few updates
per second - I don't think the 276C processor could keep up with that.

In fact some dedicated AIS units can't keep up with it! I was on a ship in
Singapore last year & the captain showed me that on his AIS transceiver (Saab
I think), if he expanded the scale to 25nm the whole transceiver would reboot
as it tried to draw all the vessels in range & crashed.

Dave

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Thanks Dave, but them I would ask You: and the NASA stand alone
"radar", or the NASA "engine"; can it support the AIS trafic? Do you
think it has a much faster processor then the 276C?
Regards

Pascal

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 05:19:40 -0700, "Pascal" wrote:

Thanks Dave, but them I would ask You: and the NASA stand alone
"radar", or the NASA "engine"; can it support the AIS trafic? Do you
think it has a much faster processor then the 276C?

Well, it's (NASA radar) got a crappier display, with no colour & no maps, so
it doesn't have anything else to do except decode & display boat positions.
However, the 276C is already pretty busy with it's large/huge colour maps to
be processed, GPS to be taken care of, etc. From my use of the 276C for the
past year(?) & extensive use & programming of AIS systems, I'd say the 276C
doesn't have enough processor power left to handle any serious AIS
requirement.

NASA engine only has to decode & output AIS via serial output, so it doesn't
need to be that fast - it's only a single task.

Dave

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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