This was Eric's recent answer to this question: Sure. I assume this is because you are playing back a post-processed wave file with audio at baseband. Further, it is not I/Q audio.
What the software is looking for is an I/Q audio stream that has an 11kHz IF. It uses a software oscillator to mix the IF down to baseband and then does DSP to demodulate the I/Q stream. When you stick a plain audio file into the stream, it still does the same thing. This is why the audio moves down 11 kHz and then ends up looking like DSB (because it is not I/Q data). If you'd like to record things in receive mode for playback later (IN RECEIVE MODE), then use pre-processed RX recording. This will record the "IF" samples and you'll get what you expect when playing it back. Eric Wachsmann FlexRadio Systems On Behalf Of Robert Cleve Subject: [Flexradio] PowerSDR SVN 701 WAV records and plays back on different frequencies If you record a WAV file and save it for playback over the air it will transmit on the same frequency that it was recorded on. However, when it is played back without activating MOX or PTT (e.g., just for listening purposes) it will shift the transmission down the band 10 or 20 KHz and display it as a double sideband waveform on the Panadapter. This happens on all bands. Does anyone have an explanation for why this occurs? > > Bob, KW4CQ -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Guy Atkins Sent: Thursday, October 26, 2006 11:10 AM To: [email protected] Subject: Re: [Flexradio] Recording a Wave File Tim, Since we're on the subject of wave file recording and playback, have you encountered offset frequencies when playing back pre-processed audio? For instance, if I record the approx. 20 to 40 kHz above & below (depending on whether I'm in 48K or 96K sampling) a local MW station at 1000 kHz, I set the SDR-1000 at 1000 kHz upon start of the playback. All is fine at that point, and I'm hearing the 1000 kHz station at zero-beat. However, if I want to tune within the recorded I.F. bandwidth up to the next station at 1010 kHz, it actually requires me to tune to approx. 1010.530 kHz. This offset is required for zero-beat of every signal within the recorded I.F. swath of frequencies, but the offset seems to vary from session to session. Also, it's very annoying that the offset bounces around if I change modes. It's really tough to use this I.F. recording feature to go back and catch DX signals if I can't rely upon something as basic as frequency accuracy / readout. Have you encountered any behavior like this before with the I.F. recording? On a related note, it would be great to see a few more basic controls for playback in the GUI, such as incremental "fast forward" or "rewind". HD recording software such as Total Recorder Pro and RecAll Pro are two excellent examples of programs that have very easy-to-use interfaces. PowerSDR's recording panel doesn't need anywhere near the amount of features found in these two, but "fast forward" and "rewind" would help out a lot when trying to find a particular spot in a long recording. 73, Guy Atkins Puyallup, WA www.sdr-1000.blogspot.com -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Tim Ellison Sent: Thursday, October 26, 2006 7:54 AM To: [EMAIL PROTECTED]; Flex Group Subject: Re: [Flexradio] Recording a Wave File Scott, Reverse the wave options - pre for RX and Post for TX There is no need to have the MOM or MOX engaged. Just play the file. There is a KB article that explains this in the works. I just have not had time to make the appropriate screen shots. -Tim --- Tim Ellison Integrated Technical Services "Noli nothis permittere te terere." - common phrase spoken by Roman slaves. _______________________________________________ FlexRadio mailing list [email protected] http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Homepage: http://www.flex-radio.com _______________________________________________ FlexRadio mailing list [email protected] http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Homepage: http://www.flex-radio.com
