AIS Receiver

[Pete]

Hoping someone can help me with how to test an AIS receiver at the dock. Our boat is located just south of New Bern, NC on the Neuse River. There is very, very, little commercial traffic on the river this far north, and our boat is back in a canal community with lots of trees between us and the river. So, no chance to get a real AIS signal to the boat.

So, I have installed an ICOM MXA 5000 dual channel AIS receiver. It is all wired up with point to point ohm meter checking of the wiring. My problem is the unit just sits there and does nothing, and ICOM support says that is what to expect until it receives an AIS signal. But, the unit would behave exactly the same way if it was DOA, or wired wrong, or anything else was wrong. Since finding real AIS vessel signals is probably an 8 hour round trip, I would like to find another way to get the unit to confirm that it is correctly installed and just waiting for the right signal.

Any ideas on a way to fake it into thinking it has a signal?

Thanks

Pete

 

[GJH]

Have you thought of calling one of the local electronics shops, such as Ensley? They may have a demo unit they can light up, or know of a local boat equipped with a transponder they can refer you to. Another option would be to take a spin down to Morehead City when some ships are in port. I also think, but do not know, that the ferries are AIS equipped. Now that I think about it, shouldn't Morehead City and the ferries be in range from where you are?

 

[scottwvyc]

The link below should be able to tell you which , if any, AIS equipped vessels are in you area.
http://www.marinetraffic.com/ais/

 

[GJH]

"marinetraffic.com" only covers selected ports. The nearest is Wilmington.

 

[PhilG57]

I had a similar problem and wrote a program called "gpswrangler" to help resolve it; I also built a web site for it. Send me a private message and we can talk more.

 

[DeeRow]

How did you connect the ICOM MXA 5000 to your navigation system?

Looking at the spec for the ICOM MXA 5000, if you installed it between your GPS antenna and your navigation equipment (you are using the ICOM MXA 5000 as a multiplexer) AND your navigation equipment is getting a GPS fix, I would think that the unit is working. If you have connected the ICOM MXA 5000 to a dedicated comm port on your navigation system and have your GPS antenna connected to a seperate comm port, it may not be working. Some GPS's are very sensitive to the voltages on the comm ports and will not work between vendors. I have seen this issue mostly connecting Raymarine GPS with non-Raymarine AIS systems and Furuno Navtex systems.

Mark

 

[DeeRow]

I had a similar problem and wrote a program called "gpswrangler" to help resolve it; I also built a web site for it. Send me a private message and we can talk more.

My experience has been that some AIS receivers will only work with RS-232, specifically PCs. Some AIS Receivers specifically state that they only work with RS-232. While the documentation on your website is not clear, it appears that your program is like hyperterm. Hyperterm uses RS-232. While an AIS receiver may work with RS-232 it may not work with a GPS.

Mark

 

[Pete]

What I need is an AIS transmitted, over the air signal. That is the only way to accomplish what I am after. Thought maybe there was some trick with a VHF radio or such that would get a reaction from the ICOM MXA 5000.

To answer the questions about my configuration, let me first tell you that with my years of employment in the computer industry, especially with a PC, if something is working reliably, I try not to mess with it. So, prior to the AIS installation I have a Northstar 940 Differential GPS, and Simrad Robertson AP20, connected to an IBM T42 Thinkpad with its dock station. The dock station has one DB9 serial port that both the 940 and AP20 are connected to through an opto-isolator cable. The Thinkpad is running Windows XP with Coastal Explorer 2009. This configuration runs at 9600 baud, is stable and does a fine job of steering the boat on its route.

Now comes the ICOM MXA 5000. All AIS runs at 38.4K baud. I could have attached both the 940 and AP20 in MXA pass through mode, but decided not to because the MXA 5000 only passes through $GPS 0183 sentences, as a listener. And since I plan to attach other instruments in the configuration, that run at 9600, I decided to leave the entire 9600 port alone and get a multiplexer for the additional instruments. That project is next after the AIS is up and running. So for the MXA 5000, I purchased a SeaLevel USB to RS232 adapter. Connected the MXA 5000 to that alone, and set that port to 38.4K. All loop back tests work out to the MXA 5000. Only item that remains to be verified is that the MXA 5000 actually receives AIS signals and sends out the proper 0183 sentences. Thus my question.

Pete Drez

 

[DeeRow]

What I need is an AIS transmitted, over the air signal. That is the only way to accomplish what I am after. Thought maybe there was some trick with a VHF radio or such that would get a reaction from the ICOM MXA 5000......

I do not know of any way to do this. Have you called ICOM? There number is 800-253-1498.

The last AIS system that I installed was on a 125' sailboat and the AIS antenna was approx. 100' up the mast. With the antenna at this height, we saw AIS targets as far away as 50 miles. You may not have to travel too far to receive targets if the system is working. I used this site to watch this boat leave the country without paying his final bill, http://gcaptain.com/maritime/tools/ais.html (edit: it looks like this site gets its data from marinetraffic.com).. There are some delays on this site. It appears to be a worldwide database and it does lose targets.

....if something is working reliably, I try not to mess with it....

I can understand this. For testing only, you could connect the 940 directly to MXA 5000. If the $GPS data is received by Coastal Explorer, then I think that you could safely assume that AIS data would be received if there were any present. Then you can wire it back to its orginal configuration.

Mark

 

[Pete]

Without any tricks to wake up the AIS receiver, I finally decided to do some wire swapping and use a few clip lead jumpers to get the 940 GPS attached to the AIS receiver port. Fired it all up and yes, the Thinkpad and Coastal Explorer reported $GPS sentences being received on the 38.4K USB port. While still running I did some other checking and noted that in the data being received, there were four different $GPS sentences. Next shut it all down and reconnected everything back to original. Verified that the $GPS sentences were now on the 4800 serial port. All is well, but I did note that now it was receiving eight different $GPS sentences. So, the ICOM MXA 5000, not only blocks non $GPS sentences, it blocks some $GPS sentences. I am more convinced than ever to use this device as only an AIS receiver on its own dedicated port. Still do not know that the unit will receive AIS transmissions, but will have to wait until I get out on the open water to check this.

Pete Drez