Open Source D-STAR voice decoding software

[Reuven Z Gevaryahu]

DSD can now decode D-STAR voice, in addition to P25ph1, DMR/MOTOTRBO, Provoice, NXDN, and X2-TDMA. I believe this is the first open-source implementation that does not use proprietary hardware. The quality is not perfect, but it is completely intelligible. I expect that will improve in future releases.

Interested users can grab the source here:

https://github.com/szechyjs/mbelib and

https://github.com/szechyjs/dsd

I'm not one of the developers on that project, but I can direct them to look here if people find issues.

--Reuven (KB3EHW)

[John D. Hays]

Just remember DVSI (owners of AMBE) vigorously enforce their intellectual property.

---

John D. Hays
K7VE

PO Box 1223, Edmonds, WA 98020-1223 

  

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[Bruce Perens]

On 12/17/2013 12:28 PM, John D. Hays wrote:

Just remember DVSI (owners of AMBE) vigorously enforce their intellectual property.

Do you have any idea what patents apply and when they expire? Perhaps we could figure this out now.

    Thanks

    Bruce

[Steve]

Decoding is only half the task :-)

[John D. Hays]

Not a patent attorney, but one claim is at http://www.google.com/patents/US6199037

---

John D. Hays
K7VE

PO Box 1223, Edmonds, WA 98020-1223 

  

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[Remco Post]

Just a note on patent law (IANAL)

patent law was originally introduced to allow research on an invention to occur. Protecting the invention trough law allowed publication of details regarding an invention that would otherwise be kept secret. The side-effect is that the inventor has a monopoly on (commercial exploitation of) his invention for a limited amount of time.

Thus, patent law allows for researchers to reproduce an invention without any explicit permission from the inventor. (I think it also allows hobbyists to do the same). You may on the other hand not sell or even give away such reproductions without the permission of the inventor.

Now, for software this is a slippery slope, and in open source software most likely a prohibitive obstacle.

Now, of course, even if a reproduction has been given away, the patent holder still has to prove that it infringes on his patent and getting something deleted from the internet is close to impossible. So DVSI may be very unhappy if people manage to build a AMBE (+ +2) implementation and publish it as OSS (open source software) on the internet, but is there really something they can do about it? I’m not saying that ‚they’ should go forth and do as they like in infringing on the "AMBE patent”, I’m just pointing out a weak point in patent law when it comes down to software and OSS.

on a personal note: I don’t like the concept of software patents, but that doesn’t mean that it’s ok to infringe on a sw patent.

— 

73 de Remco Post, PE1PIP

[Reuven Z Gevaryahu]

If anybody is going to write an open-source encoder for D-STAR, I suggest starting with the open source implementation of the IMBE vocoder used by the OP25 project. This is a C++ fixed-point implementation under GPLv3 written by Pavel Yazev. That code is available here: http://op25.osmocom.org/svn/trunk/imbe_vocoder/. Obviously the code would need to be tweaked to do AMBE+ instead of IMBE, but the fundamentals of those codecs are the same as far as I understand. Several people have used Pavel Yazev's implementation and other parts of the OP25 project code to create basic SDR p25 radios in GNURadio.

--Reuven (KB3EHW)

[Bruce Perens]

We have an intellectual property attorney who assists the project, and I spend my work day being the bridge between engineering and law. We've put in some time in developing an intellectual property strategy for the project. We are in a good position to annul patent claims of DVSI regarding our own codec, since the code was originally published as part of David's thesis 20+ years ago. Thus, we have priority over any patents that DVSI would have filed in the intervening period. They may have valid patent claims that apply to AMBE 3000, this would require further exploration. The patents they filed while working on IMBE have expired, and the ones on older AMBE versions are about two years from expiring.

Thanks

Bruce
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Sent from my Android phone with K-9 Mail. Please excuse my brevity.

[Remco Post]

Op 18 dec. 2013, om 02:19 heeft Bruce Perens <br...@perens.com> het volgende geschreven:

We have an intellectual property attorney who assists the project, and I spend my work day being the bridge between engineering and law. We've put in some time in developing an intellectual property strategy for the project. We are in a good position to annul patent claims of DVSI regarding our own codec, since the code was originally published as part of David's thesis 20+ years ago. Thus, we have priority over any patents that DVSI would have filed in the intervening period. They may have valid patent claims that apply to AMBE 3000, this would require further exploration. The patents they filed while working on IMBE have expired, and the ones on older AMBE versions are about two years from expiring.

Hi Bruce,

this is all very good news. I'm not a big proponent of D-Star per se, though I do like some of the features it provides. Having priority over some patents and the others expiring in a few years would hopefully allow people to implement D-Star more freely and give HAMs more choices when it comes down to commercially available rigs. I'm curious to see what the future brings.

Thanks

Bruce
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Sent from my Android phone with K-9 Mail. Please excuse my brevity.