On Mon, 14 Dec 2015 16:46:47 +0000 Adam Sampson <ats@xxxxxxxxx> wrote: > Will Godfrey <willgodfrey@xxxxxxxxxxxxxxx> writes: > > >> Not for audio, but having JACK run at 96000 Hz is quite useful for > >> low-cost software-defined radio... > > Explain.... please. > > A common architecture for an SDR receiver uses a quadrature sampling > detector: you mix the incoming radio signal with a pair of clocks 90 > degrees apart, and sample the two resulting signals (I/Q). Some DSP > then allows you to "tune in" any signal within the bandwidth that you've > sampled -- if my detector's clock is running at 7 MHz and I'm sampling > I/Q at 48 kHz, my SDR receiver can demodulate any signals between 6.976 > MHz and 7.024 MHz (and can receive several signals simultaneously > provided they're within that range of frequencies). > > So the advantage of sampling at a higher rate is that you can receive a > wider chunk of the radio spectrum without having to retune. High-end SDR > receivers have a dedicated ADC that can run at a high sampling rate, but > cheap radios like the SoftRock kits (http://wb5rvz.com/sdr/) use a > regular soundcard. > > I'm using a SoftRock RXTX with dttsp (and sdr-shell/softrig/fldigi), > which uses JACK for audio IO. Running JACK at 96 kHz for this means that > I can see most of the 30m amateur band at the same time... > > Cheers, > Thanks for the explanation. Very interesting stuff :) -- Will J Godfrey http://www.musically.me.uk Say you have a poem and I have a tune. Exchange them and we can both have a poem, a tune, and a song. _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/listinfo/linux-audio-user
