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Old 16-07-2016, 07:59   #1
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AIS shipname and callsign presentation

Dear forum member,

Does anyone knows how OpenCPN presents the name and callsign in the AIS massages? For example the @ sign seems to be filterd.

All information is very welcome.

Best regards,


Vincent
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Old 16-07-2016, 08:12   #2
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Re: AIS shipname and callsign presentation

Vincent...
What exactly are you asking please? Any example data feed you think we interpret incorrectly?

Pavel
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Old 16-07-2016, 08:31   #3
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Re: AIS shipname and callsign presentation

Quote:
Originally Posted by nohal View Post
Vincent...
What exactly are you asking please? Any example data feed you think we interpret incorrectly?

Pavel
Some ships have a @ sign in the name and/or callsign. As seen with other software: shipname @@@@@ is only shipname in opencpn. Some transponders were configured with the @ and some with unknown reason (eg default value not overwriten). I wondering if something happen in decoding or presentation layer.
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Old 16-07-2016, 10:56   #4
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Re: AIS shipname and callsign presentation

vincent...

OCPN filters out '@'. We assume this is a default character in un-configured AIS transponders, and that is really is not intended to be part of the shipname.

Dave
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Old 17-07-2016, 04:28   #5
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Re: AIS shipname and callsign presentation

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Originally Posted by bdbcat View Post
vincent...

OCPN filters out '@'. We assume this is a default character in un-configured AIS transponders, and that is really is not intended to be part of the shipname.

Dave
Dave,

Thanks for your reply!

Are any other characters filterd?

Best regards,


Vincent
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Old 19-07-2016, 04:52   #6
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Re: AIS shipname and callsign presentation

Hello,

I've discovered that OpenCPN shows multiple shipnames as "unknown". With my AIS receiver I captured for some time AIS data. This data has been analyzed and there is something remarkable. The AIS message type 5 sentence (which containing the shipname) is not displayed if the AIS version of that message is type 2.

All AIS messages type 5, with AIS version 0 or 1, are being displayed with the name from the messages.

Is OpenCPN incompatible with message type 5 in combination with AIS version 2?

If it is, then:
Does anyone know how I can work around this finding, in such a way that all the names (despite of the AIS version) are being displayed in OpenCPN?

Brian
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Old 19-07-2016, 09:24   #7
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Re: AIS shipname and callsign presentation

Brian...
Your assumption is correct.
The code says:
Code:
//          Get the AIS Version indicator
//          0 = station compliant with Recommendation ITU-R M.1371-1
//          1 = station compliant with Recommendation ITU-R M.1371-3
//          2-3 = station compliant with future editions
            int AIS_version_indicator = bstr->GetInt( 39, 2 );
            if( AIS_version_indicator < 2 ) {
So only AIS version 0 and 1 are handled by OCPN.
I may have encountered the same as you for some newer AIS transmitters. A boat I know has a new AIS and I've not seen the name for it but I didn't saved any messages so I can't say for sure if he was message version 2 or 3.
A suggestion would be change to "if( AIS_version_indicator < 3 ) or 4?.
Is there anyone here that can tell if such a change would cause other troubles?
Håkan
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Old 19-07-2016, 18:00   #8
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Re: AIS shipname and callsign presentation

Quote:
Originally Posted by Hakan View Post
Brian...
Your assumption is correct.
The code says:
Code:
//          Get the AIS Version indicator
//          0 = station compliant with Recommendation ITU-R M.1371-1
//          1 = station compliant with Recommendation ITU-R M.1371-3
//          2-3 = station compliant with future editions
            int AIS_version_indicator = bstr->GetInt( 39, 2 );
            if( AIS_version_indicator < 2 ) {
So only AIS version 0 and 1 are handled by OCPN.
I may have encountered the same as you for some newer AIS transmitters. A boat I know has a new AIS and I've not seen the name for it but I didn't saved any messages so I can't say for sure if he was message version 2 or 3.
A suggestion would be change to "if( AIS_version_indicator < 3 ) or 4?.
Is there anyone here that can tell if such a change would cause other troubles?
Håkan
2 is ITU-R M.1371-5, differences seem to be minor and the wording is :

1 = station compliant with Recommendation ITU-R M.1371-3 (or later)
2 = station compliant with Recommendation ITU-R M.1371-5 (or later)

In my understanding : a ITU-R M.1371-3 decoder is able to decode a ITU-R M.1371-5 message with some missing stuff.
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Old 20-07-2016, 00:35   #9
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Re: AIS shipname and callsign presentation

Hakan & Did-G,

Thanks for your reply. It's good to know that version 2 is filtered hard coded. It saves me a lot of testing. Despite of this good news, I now have to find an alternative or waiting for an update of OpenCPN that supports version 2.

- Are there free alternatives for OpenCPN?
- What is the chance for an update of OpenCPN with support of AIS version 2 in the nearby future?

Brian
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Old 20-07-2016, 00:50   #10
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Re: AIS shipname and callsign presentation

did-g....
I've briefly checked in ITU-R M.1371-5 and for our use of data we can without further changes include AIS version 3 in our message 5 decoder? (Where we are collecting ship static data.)

Do you agree?

Håkan
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Old 20-07-2016, 01:09   #11
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Re: AIS shipname and callsign presentation

Brian
re:- Are there free alternatives for OpenCPN?
Yes, but for me O is outstanding also compared to commercial stuff.

re: - What is the chance for an update of OpenCPN with support of AIS version 2 in the nearby future?
The change is very good. If discussions here come to same opinion I wrote in last post, did-g, Dave or anyone (like me) can edit the code and make a request to change in next release. The "official" way is that for example you make a future request in the Tracker/Flyspray. (See third thread in this forum)

Welcome to the world of OCPN and this forum where all kind of generous people met.
Håkan
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Old 20-07-2016, 03:23   #12
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Re: AIS shipname and callsign presentation

Brian @ all

See also Feature Requests where this is already discussed.
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Old 20-07-2016, 04:49   #13
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Re: AIS shipname and callsign presentation

There should also a few navigational status definitions be added.
I do have some time to make a push request for this, if there is not somebody working on it already.
For the time beeing it should be safe to change the
Code:
if( AIS_version_indicator < 2 ) {
in
Code:
if( AIS_version_indicator < 4 ) {
it the AIS_Decoder.cpp file and do a recompile.
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Old 20-07-2016, 05:04   #14
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Re: AIS shipname and callsign presentation

Quote:
Originally Posted by Hakan View Post
did-g....
I've briefly checked in ITU-R M.1371-5 and for our use of data we can without further changes include AIS version 3 in our message 5 decoder? (Where we are collecting ship static data.)

Do you agree?

Håkan
Yes I do.
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Old 20-07-2016, 05:52   #15
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Re: AIS shipname and callsign presentation

Thanks all..
As the consent seems general, I have just pushed the change into the master branch.
@brian192: If you are able to build from source, "the future is now"

Pavel
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