[Discuss-gnuradio] Re: FUNCube dongle

[Patrick Strasser]

schrieb Moeller on 2011-02-26 13:11:
> Sync problems? I thought, the "audio" devices implement
> a fixed sampling clock and the USB transmission is buffered to
> achieve a continuous stream without gaps or clock variations.
> Only the PC audio output has a different clock, but that problem
> occurs with other external sources too, like the USRPs.

The problem arises between system clock and audio clock. While the Audio
clock is most probably a free running clock in the device, the computer
may have a slightly different time base. Now who is right about the
sampling rate? One thing you can do is accept occasional resyncs with
small hickups or clicks, that is some lost samples or some extra
samples. Or you can resample the stream, which is computational
intensive and decreases quality. Or you manage to synchronize the
clocks, which is possible with USB. But the USB clock has probably too
much jitter for high quality signal sampling...

No easy task. Anyway, refer to SDR widget, they have thought of every
possible problem and solution.

Patrick
-- 
Engineers motto: cheap, good, fast: choose any two
Patrick Strasser <patrick dot strasser at  tugraz dot at>
Student of Telematik, Techn. University Graz, Austria