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Thread: VDL-2 Decoding

  1. #1
    First officer nzradar's Avatar
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    VDL-2 Decoding

    I've been trying to decipher the translated pages from the Japanese VDL2 decoder programme and understand what is required to decode these messages.

    It seem that if your receiver has a 10.7 MHz IF output then using that and a down-converter to downconvert the signal to 12 or 24kHz then the programme should decode successfully.

    It is unclear from the site or associated YouTube video where this down-converter comes from or how it is constructed.

    Does anyone have any ideas on how?
    Michael
    Palmerston North,
    New Zealand
    ex-FR24 Feeder

  2. #2
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    Quote Originally Posted by nzradar View Post
    I've been trying to decipher the translated pages from the Japanese VDL2 decoder programme and understand what is required to decode these messages.

    It seem that if your receiver has a 10.7 MHz IF output then using that and a down-converter to downconvert the signal to 12 or 24kHz then the programme should decode successfully.

    It is unclear from the site or associated YouTube video where this down-converter comes from or how it is constructed.

    Does anyone have any ideas on how?
    Looking at the video, he's using an AOR AR5000A receiver. I've a feeling that that 10.7Mcs output is for a video feed, and a Google search for "AR5000A+10.7" gave me this info..
    There is a programmable 10.7 MHz IF output on the back to drive the optional SDU5600.

    So, I think that the connection is a video link from the receiver to a Spectrum Display Unit SDU), in his case the SDU5600
    That begs the questions:
    What happens at the SDU end? (apart from presumably a pretty picture)
    Does one have to specifically use the SDU? (that would make it a rather expensive decoder!)
    What if you haven't got one?

    Interesting

    Rich
    The Sage

  3. #3
    First officer nzradar's Avatar
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    Rich, thanks for your thoughts though I'm not convinced the SDU comes into the equation simply because there is no mention of it on the KG-VDL web site or in the videos. I own an AR5000 and am very keen to experiment with VDL but having nothing to convert the 10.7MHz IF output to 12 or 24kHz I think is the stumbling block. This all makes sense in my mind. While the 10.7MHz output of the AR5000 can be used to connect the optional SDU the main purpose of any IF output is to down-convert the RF to a frequency standard for many other monitoring and measuring processes, i.e. bandwidth at 130MHz vs 10.7MHz is infinitely more expensive in terms of recording and storing and the use of expensive analysers for that frequency just doesn't make sense. So the monitoring of VDL for the hobbyist will need to be done at baseband (kHz) level in order to reduce cost.

    In one of the videos I saw on the Russian forum there was a small box with two cables, assume in and out that looked as if the presenter was inferring that it was a down-converter.

    Anyway, I'll keep digging!
    Michael
    Palmerston North,
    New Zealand
    ex-FR24 Feeder

  4. #4
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    Hi all, ..

    I have sucessfully used the kg-vdl program with my rtl dongle, and the software SDR Radio Console and SDRSharp...
    The thing u do is, .. to put ur software to 136.963 Mhz insteed of 136.975, and use USB wide mode.
    I also use Virtual Audio Cable, and feed kg-vdl with it, .. it works quite good accouly.

    But the bad thing with the program is the fact, it's not FREE and if u should ever have a use for it u must use it with the programs kg-acars or kg-hfdl, and in my point of wiev ... they program sucks.
    A another bad thing, .. i havent seen an upgrade of kg-vdl after i started to use it.. soo i guess it was only a hobby projekt.

    I have asked around in many forums who plays withe the rtl dongles for maybee making a good program for decoding the vdl-2 protocol.. but the intrest seems freeezing.

    To bad, i want a good program who CAN decode and send the data to lets see planeplotter for example, cose i live close to one of the biggest airport in sweden (Arlanda).

    /M

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