Thank you Helmut, Is it possible for you to measure received SNR as you increase the drive to your PA, for example at 6dB, how does the SNR look compared to 8dB?
Thanks, David On 15/09/15 18:50, Helmut wrote: > Hi David, > > My results: PAPR Mode 700B : 8 dB (200W PEP, 31W Average) > Analog SSB without compression: PAPR 9,1 dB (200W PEP, 24W Average) > > Accuracy: +/-5% (older R&S Meter) > > 73, Helmut, DC6NY > > -----Ursprüngliche Nachricht----- > Von: David Rowe [mailto:[email protected]] > Gesendet: Dienstag, 15. September 2015 10:53 > An: [email protected] > Betreff: [Freetel-codec2] (over) driving 700B > > Hello, > > I have been testing 700B on my IC7200 with a nearby FT817 connected to a > laptop running FreeDV as a test receiver. > > I had to disconnect the FT817 from any antenna and put it in a separate > room, and wind back the RF gain to get good SNR results. Rx overload > and/or pick up from the leads I guess. However I managed to get a > healthy 18dB SNR on the link using FreeDV 700B. > > I wound up the IC7200 power and "USB Level" (buried in am IC7200 menu) > all the way and still had a 18dB SNR. Unfortunately I am running off a > 12V battery, not 13.8V, so can't get the rated 100W PEP even on SSB. > The IC7200 internal power meter is hitting 60W. An external power meter > (which has a long time constant) is reading 12W average (ie a measured > 8dB peak/average). > > Has anyone else experimented with SNR while hammering your PA with 700B? > > The PAPR (crest factor) of 700B is just 8.5dB, which might actually be > better than analog speech, or similar to running a SSB compressor. > > Thanks, > > David > > On 15/09/15 16:50, wully wrote: >> I have not noticed any problem tuning the 700B mode. I am using a narrow >> filter from 700 to 2400 Hz in the SSB-passband. From the very few >> experiments we could do with dc6ny we noticed, that the locking to the >> 700B is faster than it was with the 1600 mode (just qualitatively, not >> measured). >> >> 73, hb9epu, Alfred >> >> On 15.09.2015 03:17, Peter Reichelt wrote: >>> David and list >>> As tuning is more critical on the 700 mode as compared to the 1600 mode > and there is an absence of a distinct central carrier then a couple of extra > tick marks on the FreedDV GUI showing the edges of the signal, when > correctly tuned, as well as the centre would provide easier tuning of > signals using coherent psk modes. Note this is compounded by having an even > numbers of carriers where correct tuning is with the centre tick mark > between the 7th and 8th carriers,not aligned with a carrier. It is easy to > select the mid point between the wrong carrier pair. >>> regards >>> Peter VK5APR >>> >>> > ---------------------------------------------------------------------------- > -- >>> _______________________________________________ >>> Freetel-codec2 mailing list >>> [email protected] >>> https://lists.sourceforge.net/lists/listinfo/freetel-codec2 >> >> >> > ---------------------------------------------------------------------------- > -- >> _______________________________________________ >> Freetel-codec2 mailing list >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/freetel-codec2 >> > > ---------------------------------------------------------------------------- > -- > _______________________________________________ > Freetel-codec2 mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/freetel-codec2 > > > ------------------------------------------------------------------------------ > _______________________________________________ > Freetel-codec2 mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/freetel-codec2 > ------------------------------------------------------------------------------ _______________________________________________ Freetel-codec2 mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/freetel-codec2
