[hpsdr] Digital Voice and HPSDR

[Ken N9VV]

Perhaps you fellas would be interested in the Open Source (not 
proprietary) approach that VK5DGR and the CODEC2 group is taking:

http://codec2.org/

-------------------------------------------------
<URL: http://www.southgatearc.org/news/june2010/interview_with_vk5dgr.htm
 >

Interview with Codec developer VK5DGR

One of the limitings factors in Amateur Radio experimen-tation with 
Digital Voice has been the lack of suitable Open Source Codecs.

David Rowe VK5DGR hopes to change that.

A Codec converts audio into a digital data stream and at the receiving 
end converts that data back to audio.

Amateur Radio is in need of two Codecs. One for high quality voice on 
VHF/UHF maybe using 5 kHz channels, the other a lower data rate version 
for HF that could be carried in a bandwidth of less than 1.5 kHz.

Recent experiments by Radio Amateurs with digital voice on HF have been 
very successful but they relied on the use of a proprietary software 
Codec and were at variance with copyright restrictions. For HF digital 
voice to progress an Open Source Codec is needed.

Read the Open Source Identity interview with Free Telephony Project 
founder David Rowe VK5DGR at
<URL: http://www.cio.com.au/article/264806/
open_source_identity_free_telephony_project_
founder_david_rowe/
 >

David Rowe VK5DGR Codec2 Blog
http://www.rowetel.com/blog/?p=128

The Codec2 Project
http://codec2.org/

Open source DSTAR voice - Codec2
http://www.southgatearc.org/news/june2010/
dstar_codec2.htm
----------------------------------------------------------

On 10/31/2010 4:39 PM, Glenn Thomas wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> Hi John.
>
> I've been on DV with an AOR box, though not recently, and not via an SDR
> or any sort. I would think that the AOR DV analog ODFM signals in and
> out would work as well with an SDR as with an analog radio because the
> HF SSB channel is pretty much the same when viewed from the
> microphone/speaker jack interface...
>
> My experience with the AOR system (on 40m) is that it requires more
> precise frequency control and higher SNR (maybe 10db more?) than analog
> SSB on the same channel. PSDR provides more precise carrier frequency
> control than the typical analog radio (Kenweed TS-50 in my case). The
> SNR is a function of band conditions, good luck on doing much about
> that! With a good HF channel, DV provides an audio voice-channel that
> (unsurprisingly) rivals FM in SNR but is not even as good as SSB in
> voice quality.
>
> 73 de Glenn WB6W
>
> PS. (only slightly off topic) In thinking about "additional modulation
> schemes", perhaps an interesting PSDR add-on would be software to do
> generalized ODFM (possibly defined by a selectable configuration file),
> going from audio to digital I&Q with no intermediate Dig-An-Dig step as
> happens with the AOR dongle. An open software vocoder is also required
> because the vocoder that AOR uses is (I think) closed. Has anyone tried
> to build a Huffman vocoder.
>
> Another useful function that might be provided via a general ODFM
> capability is rapid digital data transfers via HF. The 300 baud limit in
> the US (FCC 97.305(f)(3)) can be maintained while providing an effective
> data rate of up to 600 Kbyte/sec (limited in the US by FCC
> 97.305(f)(2)). That's with no data compression of any type.The AOR box
> provides something like this, but with an SDR we'd still have the
> dig-analog-dig process. Besides, an HFftp-type system should be able to
> directly access the file on both ends of the link.
>
> The generalized ODFM system can also provide traditional FSK/PSK RTTY,
> PSKnn, packet etc by simply setting the above mentioned configuration to
> use a single carrier with the appropriate modulation scheme
> (FSK/BPSK/4PSK etc) and baud rate. Thus generalized digital modulation
> could provide the SDR with whatever HF digital modulation scheme is
> desired. An additional layer over this could manage an adaptive channel
> that responds to band conditions, something that has been done before
> but not in open source.
>
> I don't have the time or the skill to implement this generalized ODFM
> system. I've only sketched it here. If anyone is interested in a more
> detailed description, drop me a note...
>
>
> On 10/31/2010 10:13 AM, John Petrich wrote:
>> All,
>>
>> Are any of you experienced with Digital Voice (DV) and it's
>> implementation with HPSDR? My HPSDR rig is running so well, that I am
>> dying to try additional modulation modes. Am I doomed to frustration?
>> I have a general familiarity with the commercial AOR9800 product. But
>> do not know if that system will work thru the PowerSDR DSP that we
>> use. Does anyone know?
>>
>> Also, I'd appreciate general reports, on or off line, on people's DV
>> experience. Is there anyone actually out there to talk to on DV? Know
>> there are WE nets on 14.236 USB. Is the AOR system the dominant DV
>> system for now and the near future?
>>
>> All thoughts would be appreciated.
>>
>> John Petrich, W7FU
>
>
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-- 
"QSD has left the building"

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