You are correct, Dave. That is why it is best to start PowerSDR first and enable VAC before starting the digi mode program so that PowerSDR can establish the cable parameters (sampling rate and bit depth).
-Tim -----Original Message----- From: flexradio-boun...@flex-radio.biz [mailto:flexradio-boun...@flex-radio.biz] On Behalf Of David Beumer W0DHB Sent: Tuesday, February 02, 2010 11:30 AM To: Joe Knapp Cc: flexradio@flex-radio.biz Subject: Re: [Flexradio] Spur in PSK31 output even with no rf out into Dummyload. I believe the VAC sample rate is set by the first program to open the VAC. If you fire up PowerSDR enable VAC then start your digital program, your VAC will be set to the PowerSDR VAC sample rate -- learned the hard way... Joe Knapp wrote: > On Tue, Feb 2, 2010 at 7:11 AM, Steven L Hess <sh...@bak.rr.com> wrote: > >> From quickly reading the VAC documentation I didn't grasp how I would >> change the sample rate from 4100 to 4800. >> As my primary audio sample rate is 48k I attempted to match the VAC >> PowerSDR setting to the same audio sample rate. >> > > I wasn't able to change the VAC sample rate to 48K either. Trying to > force it by changing the VAC range from 11025..96000 to 48000..48000 > just gave me "unanticipated host error" when starting PowerSDR. As you > say, dropping PowerSDR's rate to 44100 to match VAC eliminates the > spur. Evidently the sample rate conversion between VAC and PowerSDR > creates the spur. > > Here's a PowerSDR spectrum showing the spur: > > http://i187.photobucket.com/albums/x269/jmknapp/psdrspec.png > > Using Audacity to sample what's coming off the VAC "cable" going into > PowerSDR shows no spur (in the pass band anyway): > > http://i187.photobucket.com/albums/x269/jmknapp/audspec.png > > Joe > > _______________________________________________ > 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.flex-radio.com/ Homepage: > http://www.flex-radio.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.flex-radio.com/ Homepage: http://www.flex-radio.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.flex-radio.com/ Homepage: http://www.flex-radio.com/
