Dear Leif My experiences are limited. For AM reception I can vary the band (e.g. more lower side band, less upper side band or vv) around the virtual center, that helps a lot in handling noisy signals nearby the frequency received. I think I mean improving S/N ratio, esp for smaller signals, receiving rtty (b)psk is my favorite. My background in information theory is limited. In the series of articles in QEX on software radio for the masses (that inspired me quite a lot) there were some mysterious comments in the description of the front end signal handling where he spoke about "improving the signal" without elaborating on it.
any pointer is helpful thanks in advance jan 2009/9/21 Leif Asbrink <[email protected]> > > > Hello Jan, > > > > My esdr (sdr for elektor may 2007 and any other rig supported > > by hamlib, linux however) is for me a learning project. Currently > > front end processing is straightforward: reading samples > > with 96K, selecting a band using a bandfilter of user selectable kind > (iir, > > fir or fft conv based) then mixing with a local oscillator > > and decimating (all with lots of parameters). > > I am looking for input in improving the signal, what are > > common techniques here and I would appreciate some > > pointers to literature (preferably understandable) helping > > me further on understanding signals of this kind > > Improving signals of what kind? In what respect? > > With a usable bandwidth of about 90 kHz many different kinds > of signals are possimle. You might look for lower distortion > in the detected audio output from local MW transmitters or you > might look for better S/N of reasonably strong signals of > various kinds or perhaps better ways of suppressing impulse noise > or spurs. You might also look for a lower detect threshold, the lowest > signal level where you can desipher any reasonable amount of > information from some particular mode. > > If you narrow down your search, chances are better that you will > get some useful information:-) > > 73 > > Leif / SM5BSZ > > > > > thanks on beforehand > > janvK > > > > > > > > > > -- > > Jan van Katwijk > > > > > > +31 (0)15 3698980 > > +31 (0) 628260355 > > > > -- Jan van Katwijk +31 (0)15 3698980 +31 (0) 628260355
