Have I missed something? I don't see any relationship between I-Q and sideband suppression. I do see that Rocky - WinRadio - etc. are using the I-Q data to achieve image suppression. True sideband suppression would involve using a Costas Loop, which I don't see in any of the packages.
Chuck >From: "jr_dakota" <[EMAIL PROTECTED]> >Reply-To: [email protected] >To: [email protected] >Subject: [soft_radio] Re: Softrock as receiver back end >Date: Wed, 31 Jan 2007 19:45:44 -0000 > >There is also something to be said about using IQ demodulation to get >your sideband rejection ... Anyone who has an R2 or R2 Pro can attest >to the fact it sounds better than a crystal filter based rig even with >all analog circuitry ... so it's really a combination of digital >filtering along with IQ sideband rejection > >Based on studies of time-aligned speakers and crossovers I believe the >effect of time-aligning the I and Q channels (Necessary to get >sideband rejection, the better the rejection in Db, the better the >time and phase alignment across the passband) simply makes the audio >more pleasing to the ear and causes less ear fatigue, just as >time-aligned studio monitors are more pleasing to the ear and cause >less ear fatigue during long mixdown sessions > >JR > >-- In [email protected], "rhblumeng" <[EMAIL PROTECTED]> wrote: > > > > --- In [email protected], "i2phd" <i2phd@> wrote: > > > Ciao Claudio, > > > > > > I do perfectly agree with you. The only problem is that if you > > take > > > two different persons, they react differently to a non linear phase > > > response caused by the non constant group delay in the crystal > > > filters. It's here where it starts the subjective part of the > > > issue.... we can measure the group delay, but we can't tell anything > > > about the effect that it will have on the listeners, as each of them > > > will have a different perceived sensation of the quality of that > > > audio.... what characterize an human being is his lack of > > > predictability (and I would add, Thanks God...) > > > > > > 73 Alberto I2PHD > > > > Hi Alberto - > > > > There was something in Claudio's post that is more along the lines of > > my earlier post: > > ________________________ > > "With Ciao Radio when it is used in AM with the AM demodulator that > > implement the law of the envelope detector you clearly see the > > distortion coming in the spectrum window of the demodulated signal > > (even with dynamic signals). > > When you use the coherent AM demodulator of Ciao Radio , you don't > > have this distortion and the signal is clearer . > > This is amplitude non linearity." > > __________________________ > > > > We all assume that the better sound of the SDR is due to the dsp > > filters, and the overwhelming portion may just be that. > > > > BUT, if one can "see" the improvement we all know is there in going > > from an envelope type detector to a better type, could we not also > > use this technology to "see" subtle differences in the > > various "better" detectors (sync and others) and whether there is an > > even cleaner sound to be had from improved detector algorithms? > > > > It can be easy when something makes a great deal of improvement, to > > get caught up in celebration, and ignore other lesser, but perhaps > > valuable opportunities. > > > > I am just trying to ascertain whether more experimentation with > > detector algorithms could be fruitful... > > > > My best to you, Bob > > > >
