Nasa AIS engine connections. Help required please

[Becky]

We are fitting an AIS engine to our laptop nav computer, and we have all the obvious connections, the aerial, and the lead to the pooter, but there is a blue wire, from the 9-pin D-line plug connected to the AIS box, kind of left over.

We get our GPS signal to the pooter from a Garmin hand-held set, & the pooter runs Maxsea software.

Can we ignore this little wire? Or does the AIS thingy need a GPS input (which it doesn't get from the pooter) to be able to tell us where all the big ships are?

Anybody really clever like Tome or Talbot out there who can help with this query?????

 

[shmoo]

the extra wire is gps "in". The gps sentences would then get mixed in with AIS ones and sent to pooter (which is why the baud rate from AIS engine to pooter is so fast - to accomdate both). Only useful if pooter is short of inputs, to avoid you having to choose between ais and gps

So yes, ignore it.

 

[shmoo]

Did just occur to me if you are using a laptop, you may be short of inputs. Like you may just have the one. In which case you will need to wire the nmea out from the gps to the blue wire. Then, as I said in post above, both ais and gps sentences will come down same wire from the ais engine into your single computer serial input.

Just for avoidance of doubt, the ais engine does not itself need gps signal.

 

[tome]

Don't need the blue wire - tape it up rather than cut it off as you might decide one day to flog the NASA for a better AIS receiver (as I will first chance!)

You already have a GPS feed from elsewhere to the pooter which will be much more reliable than going thru th NASA blue wire

 

[shmoo]

[ QUOTE ]

flog the NASA for a better AIS receiver


[/ QUOTE ]

Why? Just out of interest.

I've had mine a couple of years and does does just what it says on the tin. What would you expect from a "better" one that you don't get from the NASA?

 

[Talbot]

becky

You can use the blue wire to provide GPS to the AIS, but it is better to provide a seperate feed from your existing GPS in on the puter. The programme GPSGate is the best for this. You install the programme tell it which port the GPS is using into the computer, then use the software to set up as many virtual ports inside the computer as you need. You then allocate a virtual port to the plotter and another to AIS, then you can have both bits of software working simultaneously and use "alt tab" to cycle between them.

It comes on a free 14 day tial so you can try before buy, but everybody else who has it has been happy!

As a double extra, you can use it to provide a simulation to the chart plotter, and you can also use it to record the nmea data.

 

[ParaHandy]

I wouldn't bother with it ... the GPS data re-transmitted is only position, course and speed ie waypoints etc are not. And the GPS data becomes intermittent whenever the AIS engine gets busy - not a great problem but annoying nonetheless.

 

[tome]

Quote:
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flog the NASA for a better AIS receiver



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Why? Just out of interest.

1) I'm not a great fan of the build quality of NASA

2) The internal processor cannot handle the multiplexing of GPS data with AIS data - see Para's post

3) The output level doesn't conform to NMEA standards which causes problems with some plotters

4) Not even an indicator light to show it is powered

 

[shmoo]

Thanks. I was just wondering if there was some reason I had missed but it seems not.
[ QUOTE ]

1) I'm not a great fan of the build quality of NASA

[/ QUOTE ]
The build quality of the engine, which admittedly has no moving parts so hard to get wrong, seems ok. I only has to work.
[ QUOTE ]

2) The internal processor cannot handle the multiplexing of GPS data with AIS data - see Para's post

[/ QUOTE ]
That was interesting to know. Also that it only handles a subset of senences [ParaHandy]. I don't use its multiplexing capability anyway. Certainly good to warn folks about that.
[ QUOTE ]

3) The output level doesn't conform to NMEA standards which causes problems with some plotters

[/ QUOTE ]
It drives a serial-usb bridge ok
[ QUOTE ]

4) Not even an indicator light to show it is powered

[/ QUOTE ]
Mine is mounted on a bulkhead behind the breaker panel. I don't think I've even seen it in 2 years

Some of these may be reasons not to buy but not to get rid of if its working.

Don't you think that, on reflection, you are being a little harsh?

 

[tome]

Actually, it's fine for PC connections which is how many are using it. Com port inputs (direct or via usb) are very tolerant of levels

On my setup (driving Raymarine E series) it is intermittent due to the levels - sometimes not working for a whole weekend then springing into life so unreliable. I could fit an inline buffer, but why should I have to? It's lazy engineering IMO to drive outputs below spec

The multiplexer only passes RMC sentences via the blue wire which means that the unit hogs my only NMEA port and I cannot use it with a fast heading sensor. Even RMC sentences are dropped occasionally. In my experience this happens even without an antenna connected. RMC sentences only arrive every 2 secs so it's annoying to drop them

Fast heading sensors are essential for MARPA so I can have either AIS or MARPA but not both using the NASA unit

So I don't think I'm being too harsh really. It doesn't do what I and many others need so I'll be selling it to buy a Raymarine AIS 250

Any offers?

 

[hubert]

Isn't the Raymarine AIS about five times the price of the Nasa engine?

 

[crossbones]

I have several nasa instruments and the build quality looks as good as any other. Several retailers told me they got fewer nasa returns than competing products so I tried them and haven't been disappointed.