Jitter generation compare to dithering
in [DSP]
|
From: Randy Yates on 9 Nov 2009 07:02 Randy Yates <yates(a)ieee.org> writes: > [...] > My point wasn't that such tasks don't exist, but that, in general (e.g., > without assuming such a task), the SNR of a signal that has been > dithered is actually MORE than the SNR of a signal that has not been > dithered. Bah! Correction: ...the SNR of a signal that has been dithered is actually LESS than the SNR of a signal that has not been dithered. and for > There are many signal processing tasks where only the longish term > result really matters. In those cases the average effect across many > samples is usually all you need to see a huge win from dithering. the correction: ...is usually well-worth the slight DECREASE in overall SNR. --Randy (Obviously I was thinking of the noise power, not the SNR...) -- Randy Yates % "The dreamer, the unwoken fool - Digital Signal Labs % in dreams, no pain will kiss the brow..." mailto://yates(a)ieee.org % http://www.digitalsignallabs.com % 'Eldorado Overture', *Eldorado*, ELO
From: Randy Yates on 9 Nov 2009 07:09 <begin red-faced demeanor> Randy Yates <yates(a)ieee.org> writes: > [...] This is misquoted: > and for > >> There are many signal processing tasks where only the longish term >> result really matters. In those cases the average effect across many >> samples is usually all you need to see a huge win from dithering. > > the correction: > > ...is usually well-worth the slight DECREASE in overall SNR. The correction is this: and for That's not to say that the dither was bad - the decorrelation, or more intuitively, the removal of a bunch of "spikes" in the frequency spectrum (and the corresponding increase in SFDR), is usually well-worth the slight increase in overall SNR. the correction: ...is usually well-worth the slight DECREASE in overall SNR. <end red-faced demeanor> <begin search for more coffee...> -- Randy Yates % "The dreamer, the unwoken fool - Digital Signal Labs % in dreams, no pain will kiss the brow..." mailto://yates(a)ieee.org % http://www.digitalsignallabs.com % 'Eldorado Overture', *Eldorado*, ELO
From: Greg Heath on 9 Nov 2009 08:33 On Nov 8, 3:23 am, Greg Heath <he...(a)alumni.brown.edu> wrote: > On Nov 7, 5:16 pm, Jerry Avins <j...(a)ieee.org> wrote: > > > > > > > Greg Heath wrote: > > > On Nov 5, 1:04 am, "BCLIM" <boonchun_...(a)yahoo.com> wrote: > > >> Hi, > > >> I have a doubt on jitter generation. Wonder is the method to generate > > >> jitter signal is that same as dithering generation method? Understand that > > >> both are usign random signal generation with different distribution. For > > >> example, triangular, rectangular etc. > > > > I always thought that for a signal defined over a finite length of > > > time, > > > jittering added a randomness to the amplitude whereas dithering > > > added a randomness to the starting time. > > > > Hope this helps. > > > It probably hurts. Jitter randomizes the timing of pulse edges. When you > > look at such a signal on an oscilloscope, the trace jitters. > > Given your additional comment. it helps emphasize that > terminology is application dependent. > > In the fields of classification and regression, the terminology > is as I have indicated. Unfortunate circumstance. From the comp.ai.neural-neta FAQ: ftp://ftp.sas.com/pub/neural/FAQ3.html#A_jitter Hope this helps. Greg
From: wazerface on 9 Nov 2009 10:01 Wow good dithering discussion! Yes, using a pure energy metric | |^2, dithering will always increase noise power and decrease overall SNR. But whitening often eases detection / estimation / human audio perception. The real discussion is, what is the best way to choose quantization levels for representing a given signal? P. T. Boufounos and A. V. Oppenheim, "Quantization noise shaping on arbitrary frame expansion," investigates this in general. -Martin
From: dbd on 9 Nov 2009 11:21
On Nov 9, 5:33 am, Greg Heath <he...(a)alumni.brown.edu> wrote: > On Nov 8, 3:23 am, Greg Heath <he...(a)alumni.brown.edu> wrote: > > > > > On Nov 7, 5:16 pm, Jerry Avins <j...(a)ieee.org> wrote: > > > > Greg Heath wrote: > > > > On Nov 5, 1:04 am, "BCLIM" <boonchun_...(a)yahoo.com> wrote: > > > >> Hi, > > > >> I have a doubt on jitter generation. Wonder is the method to generate > > > >> jitter signal is that same as dithering generation method? Understand that > > > >> both are usign random signal generation with different distribution. For > > > >> example, triangular, rectangular etc. > > > > > I always thought that for a signal defined over a finite length of > > > > time, > > > > jittering added a randomness to the amplitude whereas dithering > > > > added a randomness to the starting time. > > > > > Hope this helps. > > > > It probably hurts. Jitter randomizes the timing of pulse edges. When you > > > look at such a signal on an oscilloscope, the trace jitters. > > > Given your additional comment. it helps emphasize that > > terminology is application dependent. > > > In the fields of classification and regression, the terminology > > is as I have indicated. > > Unfortunate circumstance. From the comp.ai.neural-neta FAQ: > > ftp://ftp.sas.com/pub/neural/FAQ3.html#A_jitter > > Hope this helps. > > Greg So there exist neural net folks who made sloppy use of signal processing terminology too. Is that supposed to be a surprise to anyone? Dale B. Dalrymple |