NASA AIS "Radar" Receiver

[steverow]

Hi,

Anyone bought one of these yet??
Information on both the NASA and MES websites is scant.
How does it interface?
Does it come supplied with an antenna, or indeed does it need to be hooked up to a VHF radio listening on 161.975/162.025
Does it have an inbuilt GPS for own vessel fix or does it need systemic NMEA??

Any info appreciated.

Steve.


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[ccscott49]

Re: NASA AIS \"Radar\" Receiver

If it is just a reciever, it would need to be interfaced an antenna and a laptop/chart plotter, wouldnt need a GPS, because its only recieving a position, speed, heading and any other useful info etc. not transmitting it, probably in NMEA, I think!! Thats my understanding of the system.

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[colin_jones]

Re: NASA AIS \"Radar\" Receiver

It is not yet generally available. It was officially launched at METS and was nominated for an award.

It will be at LIBS and selling for about £250.

It comes complete and receives the vhf generated data which all ships over 300 tons will soon be transmitting. The 'radar' is just like NASA's other displays for navtex and weatherman. It does not need a PC display, nor GPS.

I have one here on test. It is not in a brilliant location (on my balcony) but is capturing anything within range and showing the data as a 'target' on the screen and, when interrogated by the cursor, puts up a colu,m of such info as his name, speed, distance off, bearing, direction of travel etc.

Seems interesting. I am looking forward to playing with it for real.,

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[bedouin]

Re: NASA AIS \"Radar\" Receiver

I doubt if it is NMEA, because I don't think NMEA has appropriate sentences defined (not to mention the problems with bandwidth).

Still - I look forward to seeing one - it will be very high on my list of purchases.

I wonder how much logic it will have, with an interface to the GPS it could do lot's of clever stuff with proximity alarms and predicted closest approach.

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[Robin]

Re: NASA AIS \"Radar\" Receiver

Colin, some initial questions please. How does it know distance off unless your set is connected to a GPS? Is the speed and course data he transmits the actual waterspeed & heading or is it GPS groundspeed SOG and COG? Does it show the MMSI number of the transmitting vessel too so you would be able to call him? I know you could call him by name on CH16 but that channel will eventually disappear as a calling channel.

Robin


<hr width=100% size=1><font size=1>Sermons from my pulpit are with tongue firmly in cheek and come with no warranty!</font size=1>

 

[tome]

Re: NASA AIS \"Radar\" Receiver

I believe there will be 2 versions launched, one with a screen (like a radar display) and a black-box version which outputs NMEA radar target data to external applications (PC etc). Both versions include the receiver/antenna, and the simple version will sell for around £120. Although I didn't enquire, it makes sense for both versions to have an external feed for own-ship GPS positions.

There are no plans to build a full transponder version.

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[milltech]

Re: NASA AIS \"Radar\" Receiver

I thought it had to be connected to a GPS in order to know where it is.

<hr width=100% size=1>John
http://www.on-line-marine.com

 

[Robin]

Re: NASA AIS \"Radar\" Receiver

Me too, that's why I asked!

<hr width=100% size=1><font size=1>Sermons from my pulpit are with tongue firmly in cheek and come with no warranty!</font size=1>

 

[Gunfleet]

Re: NASA AIS \"Radar\" Receiver

Why don't you read what he wrote? It knows where it is. It's on Colin's balcony! ;-)

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[colin_jones]

Re: NASA AIS \"Radar\" Receiver

Oops! Sorry! It was very early in the morning.

Because my balcony is stationary, I forgot to mention the GPS, which initially has to be connected to the NMEA output. This is simple to do with the supplied plug and cable. As long as you do not move, you can then dispense with the GPS, (mine was Garmin 128) which I did. I also used just an ordinary Vitronix V HF antenna, which happened to be to hand…... nothing special.

When the boat is moving, the system needs permanent GPS.

Interestingly, even though your own ship’s position is the centre of ‘radar-like’ screen at ‘boot up’, you can move it to several other on-screen locations to expand the ‘view’ in any direction you choose.

Tome is correct: there will eventually also be a less expensive ‘black box,’ for PC interface, but this is a bit in the future. Price is not yet decided.

My balcony version is a prototype and works fine. Production of the finished version, stand alone unit is due to start very soon and there will be stocks available in time for LIBS.

Here is not the place to try to explain the dynamic transponder technology which ships are using (even as much as I fully understand it) but there is good info at http://www.navcen.uscg.gov/marcomms/ais.htm and Mr Google turns up even more. This should answer all your questions, including those on what data is screened.

I should point out that I am not commercially connected with NASA, but just happen to be on their list of hammer and oilcan skippers likely to wreck their prototypes: so if it survives a couple of months with us, it is probably OK.




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[charles_reed]

Of course, it\'s only failing

is that you can only plot "live" transmitting targets and so is no replacement for a genuine radar.

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[steverow]

Re: Of course, it\'s only failing

"is that you can only plot "live" transmitting targets and so is no replacement for a genuine radar. "

No, true, but it makes a damn good supplement to a stand alone radar at a fraction of the cost of upgrading to a marpa enabled radar.

Steve.



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[Robin]

Re: Of course, it\'s only failing

Only if the target is one above the 300 ton that is required to install it and, like the navy is not allowed to turn it off. Pleasure vessels and fishing vessels will also not be tagged. Also for it to provide the equivalent of marpa you will need more data than the set itself will supply since your vessel is also moving. As I understand it the data you would receive is actual course (be that ship's heading or COG) and speed (again log speed or is it SOG) but it cannot tell you course and speed relative to you unless you have your data AND the ship data plotted separately ie manually or on a laptop.

I think it will have some uses, but unlike some I am reserving judgement because I don't think it is the whole solution just a small piece in the jigsaw. I don't have marpa (I don't think I would trust it either on a small boat with a simple electronic compass) and feel that if something is going to pass close enough that I felt I needed marpa then it is too close in bad visibility. Also in general terms it is usually the small so and so that causes more of a problem, big ships are usually pretty predictable even on radar.

<hr width=100% size=1><font size=1>Sermons from my pulpit are with tongue firmly in cheek and come with no warranty!</font size=1>

 

[tome]

Re: Of course, it\'s only failing

Robin

I think that the idea that AIS will become any sort of replacement for radar is unrealistic. It will certainly greatly enhance radar, but will never replace it nor was it designed to. Apart from the fact that it's only compulsory on certain vessels, you are right in stating that Naval and other vessels (including commercial vessels with security concerns) can switch it off.

Some food for thought: a full vessel report (Name, callsign, dimensions etc) is only transmitted every 6 minutes...

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[Robin]

Re: Of course, it\'s only failing

I get the feeling that people see this as a modern version of the radar detection gismo and a cheap low power consuming alternative to radar.

My biggest frights in fog have come from small boats, unpredictable fishing boat course changes, same as for small craft like tacking yachts and high speed mobos let alone a fleet of learners in Hobies tacking in L'Aberwrac'h between the reefs in 20m vis. Big ships plow straight lines, show clearly on small radar sets and have themselves superb radars on very steady platforms, the ability to know their name, callsign, course and speed is interesting but not essential and could even distract me from plotting what else is going on. I don't have a fully crewed bridge, there is me and there is her, one stares into the murk, the other plays space invaders on the radar, wondering which blob is XYZ123 on the AIS doing 17.93kts on 147degs is academic, interesting and maybe useful if time allows, but otherwise academic. As someone said about loo paper use on a dhow - too much informaion! What I need to worry about is what ISN'T showing on the AIS.

<hr width=100% size=1><font size=1>Sermons from my pulpit are with tongue firmly in cheek and come with no warranty!</font size=1><P ID="edit"><FONT SIZE=-1>Edited by Robin on 24/11/2004 16:20 (server time).</FONT></P>

 

[tome]

Re: Of course, it\'s only failing

Agree. Trials of AIS have shown up difficulties in reconciling radar and AIS targets, excessive screen clutter, etc. This on a fully manned bridge with whopping big high res screens, not the tiny low res screens we squint at whilst helming and maintaining a lookout on a filthy night.

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[Gunfleet]

how depressing

Oh you've mucked it up now. It hardly seems worth anyone's while doing. It's gone from super gizmo to useless lollypop in three posts. Mr NASA is just off to cut his throat.

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[tome]

Re: how depressing

Strangely, I would still buy one at £250 from Mr NASA if only as an aid to ship identification and communications.

WightLink ferries beware!

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[Colin24]

Re: NASA AIS \"Radar\" Receiver

I think some forumites are losing the plot here, and the “Radar” association seems to be the culprit. Only one of the numerous ways an AIS can display the data it receives is in the form of a ‘Radar like’ display. There is no question or claim that AIS could be a replacement or an alterative to radar.

It’s just a way of presenting the data in a familiar intuitive form. As has been pointed out most pleasure craft, fishing boats and in this neck of the woods (South East Asia) a fair few vessels way over 300 tonnes do not have the active system and are therefore invisible to the AIS.
We have a JRC 182 AIS transponder and find it incredibly useful in identifying ship that are approaching our work area. The conventional (albeit supa dupa) radar is essential to us as far as spotting traffic but now, rather then having to Call “The vessel in position –Blah- who is on a heading of –Blah- at a speed of –blah- etc.. in the hope that the target vessel will recognize itself and respond. We can now (in the majority of cases) either call the ship by name or via their mmsi number. I spent a bit of time on the bridge yesterday playing with the various screens and settings and will defiantly be getting one for my boat.
Apart from anything, it’s a great new toy and we all love them, Right lads?


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[Robin]

Re: how depressing

I didn't say it was useless either but some people seem to think it will do all the things a radar will do at lower power consumption and lower cost. It will not IMO be that useful if you do NOT have radar as well. Picture the scenario of several small boats equipped with AIS receivers all dodging the big ship who is tagged on their AIS, whilst blisfully unaware of each other, the fishing boat that has just done a 180 deg turn, the coaster that has altered course for the big ship and the navy frigate that doesn't want anyone to know they are there.......



<hr width=100% size=1><font size=1>Sermons from my pulpit are with tongue firmly in cheek and come with no warranty!</font size=1>