AIS - Using RX discriminator output

[VK6ADF]

Hi Leigh. Something just occurred to me. In an earlier post you mentioned using a Comar SLR200N. Now I have no knowledge of this except for what I see on web pages for it.

I see mentioned it is a network enabled AIS receiver. You connect the ethernet cable and that provides the necessary info for suitable software. To quote from one webpage I read from

Connected to a PC or Router, via the industry standard RJ45 connector, the SLR200N enables AIS data to be shared on a local network or accessed from a remote location. When connected to a PC running a compatible AIS program information can be displayed giving visual interpretation of the name, position, course and speed of vessels within VHF range.

Now I might be interpreting wrong but to me this means you do not need to connect to a soundcard. In fact perhaps any audio you hear if it has a speaker or audio output might not come from a discriminator output.

I don't know if AISmon works with the Comar but I saw a mention that Ship Plotter does. Don't know how to connect it to Ship Plotter but there's lots of menu's and submenu's to try.

[VK2KRR]

Hi Phil

Sorry to confuse you. Yes I have the Comar SLR200N, but was not having much luck with that either. The problem with it is that it gives you no indication or whats going on. Where as with the IC910 you can listen to the audio, and see signal, plus it power pre-amp up the coax. So I thought I would give the IC910 a go also.

Last night I got 17 sync and 17 errors

[VK2KRR]

44 Syncs today and 100% errors using the IC910.

Plugging the Comar SLR200N back in but dont expect to get anything as cant power the pre-amp and non tuned antenna.

[VK2GOM]

Leigh, I achieved a 200% better success with the volume turned up in Windows to see about 3/4 of the blue bar in AISMon illuminated. With the volume at half level, I only decoded one area. With the wick turned up a bit, it decoded three!

Also, check you are sampling at 48kHz on your soundcard. It needs a minimum of 48kHz to work so I read.

73 - Rob VK2GOM / G0MOH

[VK2KRR]

ok thanks Rob, will look into it.

[VK2KRR]

Hi Rob

I cant see anywhere where I can control my sound card to that extent. No options for changing sampling from what i can see.

I've turned all volumes up as much as possible. Guess will wait and see again.

[VK2FAK]

Hi all....

Ok a question I would ask is.....did you manage to get the sample file decoding correctly.....?

And if Rob has AISmon also....did he try the sample files and how did he go in decoding them...?

I would be using this as my staring point....I can't see any reason to try decoding actual vessels if the sample is not decoding right........It seems this is very touchy at the best of times and errors can be expected with live signals....but you have to start from an error free testing......well..as error free as they tell you it should be..


John

[VK2FAK]

Hi all....

Thought I would download the software and see how it runs.....

I have the 2.2.0 version.......and I downloaded the sample wav file "LA_LB_Snippet.wav" from the Files folder...

And I get the same results as is shown in the Pic on the home page of the Yahoo group.....

Not sure I am doing the same as you are...? when testing your sample wav.

John

[VK2GOM]

Using the test file, I get 99 Valid, 4 Errors. Not quite what they say, but it seems consistent each time I run it.

I think the lack of performance can only be the radio or signals are very 'down'.

I have ordered a Uniden Scanner to modify for discriminator output, and try that instead. If it works well, I can leave it going 24/7.

73 - Rob VK2GOM / G0MOH

[VK6ADF]

Its funny u mention that, because I have been doing that as ur msg come through.

It claims to have 100 valid and 15 errors when u run the wav file. The best I have managed from the file is about 50 syncs with about 5 valid the rest are errors !

Leigh, In an earlier post you said 50 sync's, 5 valid and the rest errors. Was this the LA_LB Snippet.wav file from the AISMon files section? I just installed AISMon on my laptop and ran the sample file. I got exactly the same as John and Rob, the same as the pic on the group page, ie 103 syncs 99 valid and 4 errors.

[VK2FAK]

Hi all....


i think its the same sample file he is using....on the Link in the Files it does say there is 100 valid and 15 errors..

But I wonder if he is using a cable to join two computers or running a cable between the "Line In " and "audio out"......in either case I think using the "audio out" would probably cause some issues...

If just "replaying" the file as is....and getting plenty of errors...it can only be the sound card...

John

[VK2KRR]

Hello John

I managed to get over 90% success rate with the audio file. But the syncs showing on the program from on air tests are 100% failure. I have given up for now until I have a properly tuned antenna sorted out.

I noticed that very minute changed to the audio manager can cause huge problems. So from the test file, I could get it to vary from 0 to about 95 syncs, with 78 Valid and 17 errors. To all sorts of different readings.

I do actually have an old Realistic PRO2022 here which I could modify, but will wait till I get better set up and see if the Comar will work.

Phil, yes Im pretty sure it was the file.wav u mentioned. I certainly never got close to 99 Valid syncs. When I did say I was able to get over 90% valid, that was probably only with about 85 Syncs in total from that file. Something is not right somewhere. I spent hours trying every little thing on the computer making adjustments, but it was not as good as what it stated. Maybe I need a different sound card set up ? works fine for WSPR any anything else though.

[VK2GOM]

Leigh, you will need to do this to it:

http://www.discriminator.nl/pro-2032/index.html

73 - Rob VK2GOM / G0MOH

[VK2KRR]

John in reply to ur recent msg,

I was just playing the audio through the sound card, left the line in place to the radio, but the radio was turned off when playing the file. The program indicated it had plenty of audio.
Maybe I need to feed it from audio out to line in ? Dont think I have a cord to try that just at this point.

[VK6ADF]

Leigh, you will need to do this to it:

http://www.discriminator.nl/pro-2032/index.html

73 - Rob VK2GOM / G0MOH

unless you read Dutch you had better do this Leigh http://www.discriminator.nl/pro-2032/index-en.html

[VK2FAK]

HI all...

Leigh.....interesting that you say that you just ran in through the sound card....doing nothing special...as we all did...

But I just messed about with it and adjusted the audio every which way and it had no effect....continued to get the same results.....not sure when running it from the Log file that the audio adjustments have any control..or should have any.

Just before you give up....have you tried deleting the sample log file and downloading it again......

I ran the decoded info through a program called "AIS decoder"....interesting info you can get if the ship allows it


John

[VK2KRR]

Hi John

OK I tried something different then, and opening AISMon program, went to REPLAY FILE button and then pointed the program to the Snippet .WAV file. It all was processed in about 3 seconds and I got 103 syncs, 99 valid and 4 errors exactly like it shows in the picture.

Earlier I was opening the WAV file in media player and had the AISmon program Monitoring the soundcard signal. Thats when it was all over the place. But doing it that way it plays for about ? 41 seconds...

[VK2FAK]

Hi all....

leigh that is good....clears up a possible issue....now to the next adventure..

That Media player has many things going on like buffering and god knows what...


just for the curious...I know this is not the main aim....but this is some of the info contained in that sample..

[VK6ADF]

and I ran the sample though Ship Plotter. Usually you see ship names and when clicked a popup window with info like John posted. Could not get that with the sample. Not tried to find out why at this stage. You can see what normally shows on the live grab from Sydney

[VK2KRR]

Interesting posts guys.

I tried once again last night and go 22 syncs, but 100% errors.