On 9 May 2012 10:08, Daniel Ankers <[email protected]> wrote:
> On 9 May 2012 09:56, Peter <[email protected]> wrote:
>> Well, I see there is alpha source code there. So I may look into
>> creating a test sequence (callsign and a short message) and
>> effectively sked on here with my fellow Europeans and see if anyone
>> can pick it up and decode it. Hopefully some people will now jump on
>> and agree to listen out for me if I do so :)
>>
>> I don't have a very good HF antenna setup at all right now (by which I
>> mean it's made up of speaker wire running into the garden). But, get
>> favourable results on 30/40m, less so on 20m. So should hopefully get
>> something.
>
> I can listen from IO74sd from about 1700z
>
> Dan MD1CLV

Hi Dan,

It may be a bit premature to sked. I just tried creating a 40 second
test signal with actual voice.

I used ./c2enc 1200 Codec2TT.raw Codec2TT-1200.c2
Decoding this file back to raw results in good clear audio (well very
clear considering the bit rate).

So, I used ./fdmdv_mod Codec2TT-1200.c2 Codec2TT-MOD.raw

It produced 33 seconds of modulated audio. I think perhaps this is the
bitrate difference. I also notice the modulator expects 56bit frames,
c2enc doesn't ever create 56bit frames according to the source. A new
bit rate/mode coming soon for the fdmdv?

Anyway, I thought perhaps it might still work. So I demodulated the signal back:

./fdmdv_demod Codec2TT-MOD.raw Codec2TT-DEMOD.c2
and then finally tried to get a raw file back to ensure the entire chain works.
./c2dec 1200 Codec2TT-DEMOD.c2 Codec2TT-DEMOD.raw

At which point I get a segfault. :(

I think we need to wait until the codec encoder is updated to support
the modulator code.

But, as soon as it is all working and compatible I'll fire up some
test transmissions.

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