Nasa AIS Radar questions answered

[Tech_help]

The AIS radar has a proximity alarm. When active, the audio alarm will sound if an AIS carrying vessel enters the inner range ring. The ring is 0.5, 1, 2, 4 or 8 n miles radius depending on the selected range.

The unit needs an input from a gps to position the user in the centre of the display. In a fixed installation the position can be stored and the gps removed.

Regarding ferries. All vessels over 300 tons and all passenger carrying vessels ( regardless of size ) are obliged to carry an AIS transponder.

Refering to the data update times. Vessels moving at 20 kts update position every two seconds and at a less frequent rate when stationary. Vessel names are transmitted only infrequently ( several mins between transmissions ). However the MMSI number is stored in the AIS radar so it is instantly available to the user should that vessel need to be contacted.

With regard to the name AIS radar. RADAR is an acronym for radio direction and ranging and, as such, describes the operation of the product. Like a more conventional active radar the unit also shows the past history of target positions relative to the user. While the COG and SOG of target vessels are shown in the data table, the display plots the relative positions. This basically means that if something is pointing at you then, unless you do something, it will hit you.

The AIS radar does not have an output to connect to other products. However the AIS ENGINE is a stand alone receiver designed to operate with PC chart plotters and will be available in Feb at£129- inc. It, together with the AIS radar will be on view at the London Boat Show on the NASA stand. ( S2434 )

 

[henkm]

Tech_help wrote:
"However the AIS ENGINE is a stand alone receiver designed to operate with PC chart plotters and will be available in Feb at£129- inc."

Is this official news from Nasa?
I could not find anything like this on http://www.nasamarine.com.

Henk

 

[fireball]

Re: Nasa AIS \"Radar\" questions answered

http://www.hyperdictionary.com/dictionary/radar
Definition: [n] measuring instrument in which the echo of a pulse of microwave radiation is used to detect and locate distant objects

http://space.about.com/od/glossaries/g/radar.htm
Definition: radar: A device to determine the distance and direction of movement of an object. Radio waves are sent out and reflected back from an object.

http://dictionary.reference.com/search?q=radar
# A method of detecting distant objects and determining their position, velocity, or other characteristics by analysis of very high frequency radio waves reflected from their surfaces.
# The equipment used in such detection

and from Collins Gem Pocket Dictionary:
Radar - device for finding range and direction by ultrahigh frequency point-to-point radio waves which reflect back to their source and reveal position and nature of objects sought

So I guess NASA is going for a re-definition of RADAR then.....

 

[FWB]

Yes I emailed NASA sometime ago to see if unit was waterproof.

This is their reply...


We have no plans to make the unit waterproof, however we are making an AIS
engine that will send AIS nmea data to PC and plotters etc. This will retail for
about £130. Available eary next year.

 

[Anonymous]

That sounds very interesting - I'm grateful to you for posting the details. Can you answer some of the following questions which would allow me to consider the technical issues before the BS :-

Firstly, are these two products - AIS Radar and AIS Engine? What will the £129 buy?

RE AIS Engine:-
1. What is the interface to the PC - USB, Serial?
2. Does it output the data in NMEA format - if not, how does the PC gather and interpret the data? With NASA software that is loaded onto the PC? How is the interface then arranged for compatibility with PC chart plotters? If there is a limited range of compatible PC chart plotters, can you say which they are?
3. What is the power supply requirement and is the supply included?
4. What antenna is required and where should it be mounted? Is it included in the £129?

Many thanks, David

 

[wooslehunter]

"All vessels over 300 tons and all passenger carrying vessels ( regardless of size ) are obliged to carry an AIS transponder."

Anyone know how charter boats are categorised? They do after all have to be coded. Are there any differences between skippered & bare boat charters? I'm not just thinking about yachts but also include fishing charters, diver boat charters etc etc.

 

[cruisingsam]

Re: Nasa AIS \"Radar\" questions answered

radar

• noun a system for detecting the presence, direction, and speed of aircraft, ships, etc., by sending out pulses of radio waves which are reflected back off the object.

— ORIGIN from radio detection and ranging.


From the Compact Oxford English Dictionary

Apology required methinks....

 

[BrendanS]

Re: Nasa AIS \"Radar\" questions answered

Methinks if Nasa start calling an AIS device, a radar, they will unnecessarily confuse a whole bunch of people who still don't understand AIS technology. Bad move, IMHO

 

[cruisingsam]

Re: Nasa AIS \"Radar\" questions answered

If I have been confused here apologies.
I understood the AIS radar thing to be radar with ais bolted on so that you knew what the blips were, their course, speed etc which seems to be what Tech_help is saying.
Have a look at www.dlharbour.ie and in the bottom RHS corner is a link to AIS. You have to sign up for it but just give an email address and ignore the rest of the questions to see what AIS looks like. If this is old news apologies.

 

[fireball]

Re: Nasa AIS \"Radar\" questions answered

Precisely!! I've already heard one yacht owner say he wouldn't replace his radar if it broke - he'd just get an AIS unit ... fair enough - but the AIS unit won't tell you about fixed objects - like lighthouses and entrances to marinas .... not that I'm saying you MUST have a radar, but be aware at the limitations of AIS.

An AIS Radar unit could be mistakenly bought by someone not so keen on electronics thinking he is getting a bargin, but it isn't what he thinks it is! I'd be interested - given the dictionary definitions of RADAR - what trading standard make of the name.

What I'd like to see is a unit capable of overlaying a chart, radar and AIS data.

 

[fireball]

Re: Nasa AIS \"Radar\" questions answered

Cross post! /forums/images/graemlins/grin.gif
See - you've interpreted the kit incorrectly - how many others will do the same?!
And your quote from the dictionary still said that a RADAR signal is bounced off a target ... so not just sent via VHF then ...

Don't get me wrong - AIS does seem to be a very good product, it may get a little conjested if all the pleasure boats start to transmit too, so filtering could be required.... I don't think it currently comes close to replacing RADAR though.

 

[cruisingsam]

Re: Nasa AIS \"Radar\" questions answered

Think I've interpreted it into what would be nice to have, i.e. radar with data blocks showing course, speed, destination, etc thought that was what the man from NASA was saying if he is the man from NASA?

 

[fireball]

Re: Nasa AIS \"Radar\" questions answered

Sold it well didn't he! A correct answer I assume - but not the whole picture.....
Mind u - at that price it is worth having even if you can't justify proper radar!

Handy bit of kit - but by itself it would be a little like a blind man walking down the street expecting everyone to anounce their possitions, course and speed - the lamppost doesnt so the blind man would have to know where that is, and what happens when another blind man walks down the same street? - Why do blind people have dogs ?!!?

 

[Anonymous]

Re: Nasa AIS \"Radar\" questions answered

[ QUOTE ]
Think I've interpreted it into what would be nice to have, i.e. radar with data blocks showing course, speed, destination, etc thought that was what the man from NASA was saying if he is the man from NASA?

[/ QUOTE ]

No, I don't think so and certainly not at that price. The term 'radar' seems to be a bit of a misnomer as others have said. I have Raytheon MARPA that does some of what you mentioned, but no destination or MMSI. Also the COG and SOG are not very accurate but nevertheless, it is very handy in congested waters such as the channel around TSSs where the traffic concentrations are high. I am very interested in this new product and will almost certainly buy one. A key benefit would be the ability to send a DSC call which might be nice in bad viz in congested waters or offshore if you wanted assistance.

 

[cruisingsam]

Re: Nasa AIS \"Radar\" questions answered

yep he sure did! i remember going into a air traffic control place a few years ago and they had the radar with AIS but it was called something else, they rolled the cursor over a blip and got the data box showing height, speed, direction, destination, plane type etc etc that was what i was thinking!
Actually think the AIS on its own would be more dangerous than sailing without anything, you would "see" other ships but not know where they were <edit> in relation to "fixed" objects <end edit>
As to the definitions I was just refering to the origin of RADAR, not the scientific stuff

 

[Scarron]

Re: Nasa AIS \"Radar\" questions answered

Whilst you are quite correct in quoting dictionary definitions of what radar is and how it functions, you seem to have missed 'tech help's point the point;- when Radar was being developed on the thirties by various parties it became commonly known as Radar = Radio detection and ranging, which is exactly what Nasa are describing their device as. It is I agree a little confusing but not incorrect.

I for one will look seriously at it [bearing strongly in mind that it will only show up large moving objects] for £130 I'd love to be able to see Red Jet III coming towards me at 35 knots in the confusion of lights that the solent at night can be.

 

[Anonymous]

Re: Nasa AIS \"Radar\" questions answered

[ QUOTE ]
Actually think the AIS on its own would be more dangerous than sailing without anything, you would "see" other ships but not know where they were <edit> in relation to "fixed" objects

[/ QUOTE ]You mean that having extra information would somehow be 'dangerous'? Surely that depends on how you use that information. If I didn't have a radar I would still be delighted to have an accurate postion, SOG, COG and MMSI for all the local vessels that are equipped. Imagine you hear the sound of heavy machinery in thick fog and your AIS is telling you that there is a large vessel only a few cables from you, its course and speed, and even its name. It would be very comforting to be able to plot out the scenario.

 

[cruisingsam]

Re: Nasa AIS \"Radar\" questions answered

just searched Raytheon for marpa and no "hits" but i can find out about ACM's (Advanced Cruise Missiles) /forums/images/graemlins/tongue.gif

 

[Anonymous]

Re: Nasa AIS \"Radar\" questions answered

[ QUOTE ]
just searched Raytheon for marpa and no "hits" but i can find out about ACM's (Advanced Cruise Missiles) /forums/images/graemlins/tongue.gif

[/ QUOTE ]It's under Raymarine who took over the Raytheon name.

http://www.raymarine.com/raymarine/Default.asp?Page=371&Section=2

 

[fireball]

Re: Nasa AIS \"Radar\" questions answered

http://www.raymarine.com/raymarine/default.asp?site=1&section=2&page=371
for raymarines page on marpa ....
Some have said the M stands for Manual not Mini ... I haven't tried a set yet though ...