If you are concerned about the sidebands or carrier that you see (I think I have seen it as well), I just created a narrower transmit bandwidth with a high pass of 300hz and a low pass of 2000hz (or something like that).
Mike va3mw On Tue, Nov 20, 2012 at 11:54 AM, Brian Lloyd <brian-wb6...@lloyd.com>wrote: > On Tue, Nov 20, 2012 at 8:37 AM, Steven Catani <sjcat...@gmail.com> wrote: > > > When I transmit, the signal as displayed in the panadapter shows broad > > tails and what looks like lots of harmonics. It also has "blips" every > sec > > or so where it looks like an envelope over the entire signal shows up... > > this is more apparent if average is turned off. I can reduce the > harmonics > > by narrowing the transmit filter but this seem kludgy to me. I have made > > 30+ contacts but something feels wrong. > > > > The "blips" every second or so are the sidebands from the frequency > modulation when JT65 changes tones. Remember, every time you change > amplitude, frequency, or phase, you get modulation sidebands. > > I am not sure what you mean by "tails". If you are seeing many spectral > lines other than the carrier at time other than when JT65 is switching > tones, you may be overdriving the TX audio section. Start by setting the TX > meter in PSDR to read mic level. Make sure that the mic level (actually the > audio input level) never exceeds 0dB. I normally set VAC TX gain to produce > -1dB for MFSK modes like JT65, WSPR, Olivia, MFSK-16, etc. For PSK31 or > other digital modes that have a significant amplitude component I use -2dB > or -3dB to ensure I have headroom and won't clip the signal in the audio > stages. > > -- > Brian Lloyd, WB6RQN/J79BPL > 3191 Western Dr. > Cameron Park, CA 95682 > br...@lloyd.com > +1.767.617.1365 (Dominica) > +1.916.877.5067 (USA) > _______________________________________________ > FlexRadio Systems Mailing List > FlexRadio@flex-radio.biz > http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz > Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ > Knowledge Base: http://kc.flexradio.com/ Homepage: > http://www.flexradio.com/ > _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/
