Yes the 11K sample rate may be a problem with the 'new' time critical modes, wspr used to have a sample rate problem where the card rate reduced the 'tx' time and caused problems with sync frames , the othere week while running Ros MF-1/7 on 500 Khz , local decodesd where scrabled , as if there was -rf- in the audio.. after checking and finding all was fine..spotted that digipan had pulled the card clock to 11K , re set the driver to 48k and all was fine, my st5 dident have these problems
G.. --- In digitalradio@yahoogroups.com, "g4ilo" <jul...@...> wrote: > > > > --- In digitalradio@yahoogroups.com, Peter Frenning <peter@> wrote: > > > > > The Signalink USB (which I recommend myself with the caveats on my > > homepage), uses one of the same Cheap chips used by the low cost general > > purpose adapters, in this case the "USB Audio Codec". As a class of > > devices you are certainly correct in your assumption about the drivers, > > but again, as a class of devices, they support all std. sampling rates > > from 48000 and down, with one notable exception: 11025 (this became a de > > facto std many years ago when it was the fastest rate these newfangled > > devices (i think the first was a SoundBlaster 8-bit adapter) would do), > > many many applications default to this, and for compatibility reasons > > its being fudged in the Windows driver SW rather than aborting the > > requesting application. Funny enough (or not as things may be) Linux > > drivers don't do this and abort any application requesting 11.025 from > > one of these devices! (this is the only case I know of where resampling > > comes into play). > > > > Anyway, if your purpose isn't high quality HiFi or ultra high sampling > > rate for SDR radios, i can recommend the cheaps sound cards - get real, > > they have more than sufficient dynamic range, and you only need a > > frequency response of some 500-2500 Hz anyway! > > > > But there is more than frequency response and dynamic range required to > preserve the information needed to decode digital modes. > > Your statement that the cheap devices do not support 11.025kHz sample rate > may have something to do with why I found them so poor as that is the (fixed) > rate used by the AGWPE soundcard packet modem. It is also the default rate > used by MixW. > > As I said before, I could see the signal on the waterfall but it was just not > being decoded. Really, if you want to be confident you have the best chance > of decoding that weak signal it is better to be using a good quality device. > After all, you spend hundreds if not thousands of pounds / dollars on the > transceiver, why penny pinch on the sound card? > > Julian, G4ILO >
