Hello Bill- Thanks for taking the time to explain the complexity of dealing with SDR Digital Data. Bill W2PKY
On Mon, Nov 1, 2021 at 10:38 AM Bill Somerville via wsjt-devel < wsjt-devel@lists.sourceforge.net> wrote: > Bill, > > typical SDR console applications deliver samples via audio devices, some > have other mechanisms but most of those are not to a common standard. What > is actually passed over an audio device stream need not be audio, for > example many (most) SDR consoles are capable of producing (and consuming in > a few transceiver cases) I/Q sample data as a stereo pair of interleaved I > and Q data streams. This is usually necessary since consuming applications > wish to constrain the sample rate and do not want the full bandwidth of the > SDR sampling circuits - this is what the SDR console application should be > doing to provide the sample rate the consumer requests. Nor do consuming > applications wish to control the ever increasing number of SDRs, e.g. to > set the centre frequency, filter settings, gain settings, etc., each with > their own proprietary mechanism. > > WSJT-X is not a general purpose SDR console, currently it consumes a > baseband 16-bit PCM audio sample stream at 48,000 Hz sample rate. In future > it may have a wide-band option to consume something along the lines of a > 96,000 Hz I/Q data stream pair. Note this is a non-trivial change as the > DSP processing in WSJT-X is built on the assumption that the input data is > 48,000 Hz bandwidth, and furthermore the first processing step is a > downsample and LPF to 12,000 Hz. It is not really relevant that the data > arrives a baseband PCM audio, rather it is the bandwidth requirement that > determines the following processing steps to decode signals. > > So to answer your question, no to the first, WSJT-X is not trying to be a > general purpose SDR console. As to the second, it is not really relevant > how the sample stream is delivered, but as PCM data, perhaps misused > repurposed to covey I/Q data, it is a very convenient cross-platform data > transfer mechanism for sample data. Note there should be no "Windows audio > processing" if the sample rate is consistent throughout and the levels are > set to 0 dB (FS) throughout. > > 73 > Bill > G4WJS. > > On 01/11/2021 13:59, Bill Barrett via wsjt-devel wrote: > > Hello Bill- > Do you see a possibility that WSJT-X might one day have a direct > connection to SDR Digital Data Stream input bypassing the typical DAX > module and Windows audio processing? > > Thanks; > > Bill W2PKY > > On Mon, Nov 1, 2021 at 9:48 AM Bill Somerville via wsjt-devel < > wsjt-devel@lists.sourceforge.net> wrote: > >> On 01/11/2021 12:22, Dave Fitches via wsjt-devel wrote: >> > I recently got another RTL-SDR to hook up to my system. (Win 10) >> > >> > I was planning to run one using WSJT-X running FT8, the other another >> > running WSPR >> > >> > However... it seems that WSJT-X will only recognise ONE Virtual Audio >> > Cable (VAC)... >> > >> > I recently set up two additional VAC's (for a total of three) and they >> > work perfectly - unless I'm using WSXT-X which will only recognise ONE >> > on the Soundcard Input feed, though it DOES show all THREE VAC's on >> > the OUTBOUND sound card selection... >> > >> > Similarly (and no surprise because it's using the same code) JS8Call >> > has the same issues. >> > >> > I'm using the VAC software from V.Burel / JS-Loezic - >> > https://vb-audio.com/Cable/ >> > >> > -- >> > >> > >> > = Dave Fitches = >> >> Hi Dave, >> >> no one else has reported a similar issue. I have VAC installed (not >> VB-Cable but similar) with 8 devices and that all show up in both WSJT-X >> audio input and out devices as expected. do other applications that use >> audio devices via the MME audio sub-subsystem like Audacity show them? >> >> >> 73 >> Bill >> G4WJS. > > > _______________________________________________ > wsjt-devel mailing list > wsjt-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/wsjt-devel >
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