Sorry to hijack thread, what is the cause of the *helicopter noise. *I
observe this occasionally also in my implementation on the STM32 which is
derived from the stm32 code. It has been interfaced with a IoT radio and I
intend to make it available pretty soon however this helicopter noise is a
source of irritant. Initially I thought the it is RFI but shielding also
did not solve it completely.
best,
Akshay
On 28 January 2017 at 09:57, David Rowe <[email protected]> wrote:
> Just had a 30 minute QSO with a local Ham (vk5apr) on 7.177MHz using
> 700C. Peter has the Windows version, I have a Linux version of FreeDV,
>
> Few little issues I'll look into, like helicopter noises with 700C in
> analog mode, and providing a BER estimate.
>
> Our consensus was not as good at 1600, but still quite usable for a
> conversation.
>
> We pushed the power level right down until we hit 0dB SNR at which point
> the audio started to become unintelligible. At this level the modem
> tones were quite down in the noise when listening in analog mode. SSB at
> roughly the same level was a 100% copy but noisy. Although hard to
> compare power levels exactly.
>
> Next step - would like to try it on a channel with fading.
>
> Cheers,
>
> David
>
> On 28/01/17 07:57, Helmut wrote:
> > Thanks David, I'll check the test waves tomorrow.
> >
> > 73, Helmut
> >
> > -----Ursprüngliche Nachricht-----
> > Von: David Rowe [mailto:[email protected]]
> > Gesendet: Freitag, 27. Januar 2017 20:46
> > An: [email protected]
> > Betreff: Re: [Freetel-codec2] FreeDV 700C early release
> >
> > Hi Helmut,
> >
> > Hmm, that's a mystery but maybe I have missed something. I can run 700c
> > between linux and windows machines here on the bench. I have a report
> > from others running the SVN release below OK.
> >
> > Do the 700c/800xa test wave (links below) files decode for you?
> >
> > Thanks,
> >
> > David
> >
> > On 28/01/17 05:26, Helmut wrote:
> >> Hi David,
> >>
> >> Together with my friend Alfred, HB9EPU, I started today a first trial
> with
> >> early freedv-windows-2996. Alfred used svn 2978 in his particular
> > Linux/SDR
> >> environment. As the test of mode 700C failed, I easily selected mode
> 700B
> >> while Alfred had to move over to 700B using now svn 2299. All worked
> fine
> > as
> >> experienced in the past.
> >> Double check back to 700C: same failure.
> >>
> >> Any ideas, why 700C didn't work? Was there any modification of the modem
> >> features?
> >>
> >> 73, Helmut, DC6NY
> >>
> >>
> >> -----Ursprüngliche Nachricht-----
> >> Von: David Rowe [mailto:[email protected]]
> >> Gesendet: Donnerstag, 26. Januar 2017 06:45
> >> An: [email protected]
> >> Betreff: [Freetel-codec2] FreeDV 700C early release
> >>
> >> Over the past few months I've been working on a new 700C bit/s speech
> >> codec. The idea is to make it roughly the same quality as the FreeDV
> >> 1600 mode but at a lower bit rate so it can punch through HF channels
> >> better.
> >>
> >> I had a huge response to a recent blog post on the 700C codec:
> >>
> >> http://www.rowetel.com/?p=5373
> >>
> >> We now have an early version of the FreeDV GUI program for Windows
> >> available, that runs "FreeDV 700C":
> >>
> >> http://rowetel.com/downloads/freedv-windows-svn-2996.tar.gz
> >>
> >> Richard is also working on a version with a proper installer, but in the
> >> meantime I'd welcome any feedback on 700C/800XA.
> >>
> >> I can't guarantee the bit stream will be stable (hence the early release
> >> tag), but I'll let people know if it changes.
> >>
> >> As a bonus it also supports the "800XA" mode developed by Brady - which
> >> is the 700C codec with a FSK modem. FSK lets you push a bit more power
> >> through your PA than the normal PSK modem used for FreeDV 700C. It
> >> might also let the smoke out of your SSB PA so pls be careful.
> >>
> >> Here are some wave file you can use to test 1600/700C/800XA:
> >>
> >> http://rowetel.com/downloads/codec2/ve9qrp_1600.wav
> >> http://rowetel.com/downloads/codec2/ve9qrp_700c.wav
> >> http://rowetel.com/downloads/codec2/ve9qrp_800xa.wav
> >>
> >> Play them into FreeDV using the "Tools-Start/Stop Play File from Radio"
> >> option.
> >>
> >> Thanks,
> >>
> >> David
> >>
> >>
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