--- In [email protected], "Vojtech Bubnik" <[EMAIL PROTECTED]> wrote: > > Hi Alberto. > > I built SoftRock RXTX and I am trying to use it on two laptops with on > board audio. I am experiencing a lot of dropouts in other SDR > programs, but your WinRad works just fine. I measured that the audio > in clock is quite off from audio out clock. At 8ksamples per second RX > samples 8001.5, TX samples 8000.7 samples per second. Did you > implement anything specific to tackle this problem? > > Thanks, Vojtech OK1IAK, AB2ZA >
Hi Vojtech, glad that you find Winrad useful. The difference in input sampling rate and output sampling rate is a common problem in sound cards, and probably is the cause of the dropouts that you experience in some programs. If buffers are produced at a slower or faster rate than consumed, sooner or later you will have either a buffer underflow or overflow. In Winrad there is fractional resampler that, whatever the input sample rate is, downsamples the signal down to 11025 Hz (for AM, SSB and CW), using a resampling ratio that is not an integer value. Then, monitoring the length of the output buffer queue, Winrad dynamically adjust this resampling ratio by small amounts (often by a few parts in 10^-3) to try to keep this buffer length constant. If you want to see it at work, just open the Winrad Status panel (you will find the button to do this under "ShowOptions") and there you will find the current value of the fractional resampler. 73 Alberto I2PHD
