Hi Gerhard Is there any change to the shoulder if you disable "pure signal" ?
Regards Peter ------ Original Message ------ From: "David Rowe" <[email protected]> To: [email protected] Sent: Friday, 3 Feb, 2017 At 4:45 PM Subject: Re: [Freetel-codec2] FreeDV 700C early release Hi Gerhard, This actually dovetails neatly with Steve's PAPR work in the last post to this list. Unlike the 1600 and 800 modes, the COHPSK modulator used for 700C has some clipping on the output to improve the PAPR. In some PAs, this means you get get a higher average power output. In others, it may let the smoke out. This amplitude limiting is a form of non linearity and is probably the cause in the spectral regrowth at the edges of the spectrum that you are observing. Clipping can be disabled in the FreeDV GUI program Tool-Options menu. Cheers, David On 03/02/17 16:26, Gerhard Burian wrote: > Hi David, > > When I was testing the different modes with websdrs I recognized > higher > sideband noise (shoulders) in 700C mode compared with 800XA and 1600 > mode at > the same settings on my ANAN-100D. I am using narrow filtering on TX > and > pure signal. So I don't have an explanation for that. > > Regards > Gerhard > > -----Ursprüngliche Nachricht----- > Von: David Rowe [mailto:[email protected]] > Gesendet: Dienstag, 31. Jänner 2017 11:40 > An: [email protected] > Betreff: Re: [Freetel-codec2] FreeDV 700C early release > > I been sending a few SSB/700C test signals of 800 - 1500 km paths on > 40M > using a websdr to pick them up at the other end. In marginal > conditions > with SSB down in the noise I'm getting sync and audio through on 700C. > Not sure if I have the same average tx power though. > > Also had a 700C QSO with a guy interstate. SSB very noisy but 6-8dB > SNR on > 700C. Noise free but some issues with his audio and the modem loosing > sync > every few seconds. > > Lot of frequency selective fading in both tests. > > Promising start.... > > - David > > > ---------------------------------------------------------------------------- > -- > Check out the vibrant tech community on one of the world's most > engaging > tech sites, SlashDot.org! http://sdm.link/slashdot > _______________________________________________ > Freetel-codec2 mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/freetel-codec2 > > > > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, SlashDot.org! http://sdm.link/slashdot > _______________________________________________ > Freetel-codec2 mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/freetel-codec2 > ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ Freetel-codec2 mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/freetel-codec2 ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ Freetel-codec2 mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/freetel-codec2
