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Thread: Converting analogue repeaters to P25

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    Forest No Longer Registered

    Default Converting analogue repeaters to P25

    There is a German modem board, DVRPTR, which is now being manufactured in Canada that, when connected to an analogue repeater, converts it to a D-Star repeater. It has the ability with alternative firmware to provide the same feature for P25.

    The source code is open source and is written in C. To create a P25 version would require someone with C and P25 knowledge: support is available from the designer.

    I have been using the board for some time in a D-Star environment and it has been proven to be reliable (as well as cheap). I am sure that if a P25 version becomes available it could result in a significant increase in P25 repeaters and usrs. In Australia more than half of the D-Star repeaters are based on this board which is also used to create hotspots for access to the D-Star network.

    So, the purpose of this post is to see if anyone with the necessary skills is interested in having a crack at the firmware? If so, PM me and I will provide any other info you require.

    Hopefully we can get this off the ground.

    Howard
    VK4BS/VK4RPH


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    ...and intimate knowledge of DSP techniques as well....

    Quote Originally Posted by Forest;****8
    To create a P25 version would require someone with C and P25 knowledge

    I'm also interested where the documentation is for the hardware and any other software APIs that this thing provides - I've googled around but it doesn't seem to be obvious..

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    Here is the Yahoo Group: http://tech.groups.yahoo.com/group/DVRPTR/ and the web site in Germany is: http://www.dvrptr.de

    I've been watching the Group and I think some time in November last year the original designers gave up on Version 1 of the board and the P25 ideas.


    @Mat/Howard you're already both members of that Group???


    Last edited by Astro Spectra; Feb 26, 2013 at 05:32 AM.
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  4. #4
    Forest No Longer Registered

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    First up, the source code will be on Git shortly - it is presently on sourceforge. To quote a recent reply to me in the V1 forum:

    "Hi Howard,

    the code is open source and we will be moving it to Git hub very shortly.

    We would be very happy for people to start working with the code

    I am sure that Jan would be happy to answer any questions on the code that people may have

    Regards
    Bruce Given"

    Jan is the original developer.

    Let's hope someone is able to work with this: it would be great to have this means to create P25 repeaters!

    Howard


    Quote Originally Posted by MattSR;****9
    I'm also interested where the documentation is for the hardware and any other software APIs that this thing provides - I've googled around but it doesn't seem to be obvious..
    Last edited by MattSR; Feb 26, 2013 at 05:49 AM. Reason: Fixed Quote tags

  5. #5
    Forest No Longer Registered

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    That's pretty right but Jan, an original designer/developer is working with the new Canadian group to get a V1 back on the streets. The URL for the new V1 yahoo group is http://groups.yahoo.com/group/DVRPTR_V1/

    And, yes, I am a member of all the groups tied in with the hardware and software.

    Howard

    Quote Originally Posted by Astro Spectra View Post
    Here is the Yahoo Group: http://tech.groups.yahoo.com/group/DVRPTR/ and the web site in Germany is: http://www.dvrptr.de

    I've been watching the Group and I think some time in November last year the original designers gave up on Version 1 of the board and the P25 ideas.


    @Mat/Howard you're already both members of that Group???



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    Quote Originally Posted by Forest View Post
    Let's hope someone is able to work with this: it would be great to have this means to create P25 repeaters!

    Howard
    Yep, and theres enough Open Source P25 projects out there to make it fairly easy - most of the work is in porting the code from GNUradio into the DVRPTR platform.

    The OP25 project already has a soundcard based transmitter and receiver stack that was written by Max. It transmits and receives P25 using soundcard inputs and outputs to generate the waveforms in the exact same mannner that the DVRPTR does. I believe that moving this into the DVRPTR would be the simplest approach. The GNUradio framework might introduce a bit of fat would need to be trimmed out in order to make it run efficiently on the DVRPTR, since it uses an AVR as its processor, but given it can be done with DSTAR, P25 should be doable also..

    Cheers,
    Matt
    Last edited by MattSR; Feb 26, 2013 at 05:58 AM.

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    Moved to P25 amateur forum.

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    Quote Originally Posted by Astro Spectra View Post
    Here is the Yahoo Group: http://tech.groups.yahoo.com/group/DVRPTR/ and the web site in Germany is: http://www.dvrptr.de

    I've been watching the Group and I think some time in November last year the original designers gave up on Version 1 of the board and the P25 ideas.


    @Mat/Howard you're already both members of that Group???

    G'day John, Yep I've already joined up a while ago, but there doesn't seem to be much in the way of developer documentation in either of those places. I've asked the question on the mailing list to see whats available there.

    Interesting that there has been a split with V1, V2 and the P25 idea...

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    @MattSR: could you give some more info about this P25 soundcard project please?
    The DVRPTR development group has given up the P25 idea due to lack of P25 knowledge.

    Otherwise, the DVRPTR V1 hardware is the best DV add-on I've seen for this price, unfortunately it only does DSTAR.
    (Which is an awfull "standard", because no proper error correction and Middle-Age style low quality voice...)

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    Quote Originally Posted by SwissMoto View Post
    @MattSR: could you give some more info about this P25 soundcard project please?
    Its OP25 - I've publicised the living hell out of it over the past 5 years or so and people are probably getting sick of hearing me talking about it.. op25.osmocom.org

    Quote Originally Posted by SwissMoto View Post
    The DVRPTR development group has given up the P25 idea due to lack of P25 knowledge.
    From reading the mailing list, the specific problem appeared to be achieving decent clock recovery on C4FM - which is strange because Muller-Mueller and Costas loop have been been around for decades. Motorola refer to some proprietary device called a "Stochastic Gradient Clock Recovery Device", and the P25 specifications say "The method of clock recovery is left up to the manufacturer" which kinda implies theres some tricks in there that Motorola kept to themselves.

    In any case, Max, KA1RBI, has spent many many hours solving these problems for P25 CQPSK (as used in LSM), and Frank (of radiorausch fame) built a very good C4FM slicer that works in GNUradio, OP25 uses these and they work very well.

    Cheers,
    Matt
    Last edited by MattSR; Feb 26, 2013 at 11:31 AM.

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    Thanks, Matt!
    I am quite new to this group and was not aware of your previous OP25 postings... and certainly didn't want to hurt anybody's feelings!
    Will have a look at the Osmocom site.

    Cheers,
    Nick

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    No worries mate, I'm just wary of sounding like a broken record, thats all!



    I hope my post gives you a few pointers..

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    FYI - As it turns out the V2 DVRPTR is closed source, and the guys on the main list actually pointed me to the V1 instead.

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    Well I can't find the source code anywhere - and the DVRPTR site is a bit broken... Anyhow, I'm keen to have a look at these things (even though DSTAR isn't my thing) to check them out!


    Quote Originally Posted by Forest View Post
    First up, the source code will be on Git shortly - it is presently on sourceforge. To quote a recent reply to me in the V1 forum:

    "Hi Howard,

    the code is open source and we will be moving it to Git hub very shortly.

    We would be very happy for people to start working with the code

    I am sure that Jan would be happy to answer any questions on the code that people may have

    Regards
    Bruce Given"

    Jan is the original developer.

    Let's hope someone is able to work with this: it would be great to have this means to create P25 repeaters!

    Howard