Hi Glen, don't overstrain guys with more abbr. They just heard of IMD, IP3, PIM etc., hi. Greetings from hot Central Europe to down under!
73, Helmut, DC6NY -----Ursprüngliche Nachricht----- Von: glen english [mailto:[email protected]] Gesendet: Sonntag, 26. Juli 2015 09:07 An: [email protected] Betreff: Re: [Freetel-codec2] Setting SM1000 transmit level I'd expect most ham stuff will produce lots of IPM when worked hard. The IPM might be your limit on the IC7200 Has anyone measured the IPM ? oh that's INCIDENTAL PHASE MODULATION. there is usually an (unwanted) relationship with amplifiers between amplitude and phase. IE crosstalk from AM >> PM. glen . On 26/07/2015 7:49 AM, David Rowe wrote: > Hi Michael, > > FB on getting your SM1000 up on the air - lets have a QSO some time! > > Adjusting so your ALC just moves, and 20-25 watts average power for a > 100W PEP rig is a useful rule of thumb for FreeDV 1600. The classic > "rookie mistake" is overdriving the SSB tx, which causes clipping and a > poor bit error rate at the receiver. Make sure any speech compression > is off too. > > The best way to adjust your tx drive is monitor the SNR of the signal > using a 2nd rx and the FreeDV GUI program. For example when I tx with > my IC7200, I have a FT817 nearby with no antenna and the RF gain wound > down. I feed the rx audio into my laptop and monitor the scatter > diagram and SNR. Incidentally, with my IC7200 I can't seem to get > better than 20dB, perhaps due to it's sharp tx filtering. > > I have a video that demonstrates this (and explains scatter plots): > > http://www.rowetel.com/blog/?p=3109 > ---------------------------------------------------------------------------- -- _______________________________________________ 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
