"Rune Allnor" <allnor@tele.ntnu.no> wrote in news:1144296831.640916.112470@g10g2000cwb.googlegroups.com:> > Rick Lyons skrev: >> Hi Guys, >> I was asked to review a potential article >> for the IEEE Sig. Proc. magazine. In that >> article the author implies that IIR (recursive) >> filters aren't as popular nowadays as they were in >> the past (say 10-20 years ago). >> >> Now I'm no IIR filter designer, so I need your >> opinions. Aren't IIR filters still as popular >> now for audio signal processing as they were >> 10 years ago? > > I don't know the relative popularity of IIRs and FIRs 10 years ago, > but I suspect IIRs will be a thing of the past in 10 year's time. > > IIRs are difficult to design unless you have some dedicated > software. You don't have that unless you need it (like if you > are designing for low-power gadgets), so no one have that > software. In comparison, FIRs are easy to design using the > window function techniques. Eveybody can do that, you can > get there with a calculator an a little patience.I use computer programs for both.> > A few monts ago I implemented my own rudimentary IIR filter > design software. With one notable exception, the book by > Andreas Antoniou I have mentioned her a couple of times, > no texts on DSP do much more than mention IIRs in > passing. Some 80% of my job when implementing that > package was actually finding the relevant material (I only > found the Antoniou book after I was finished).I bought this book yesterday. It includes a licence to an IIR filter program (which I haven't looked at yet). The book does cover IIRs better than just about or maybe all my other books. I think it will be a good addition and thank you for suggesting it. BTW, I have a very old edition of the Antoniou book. It is much less complete or useful. It is also about 1/3 the pages.> > So yes, my impression is that the authors of your article > may be right, or at least there is a trend. IIR filters might > just be on their verge to become obsolete. >I don't think so. There are plently of advantages to IIRs over FIRs (and the converse). The tradeoff is only where the filters can be used interchangably. -- Al Clark Danville Signal Processing, Inc. -------------------------------------------------------------------- Purveyors of Fine DSP Hardware and other Cool Stuff Available at http://www.danvillesignal.com
IIR filter question
Started by ●April 5, 2006
Reply by ●April 7, 20062006-04-07
Reply by ●April 7, 20062006-04-07
On Thu, 06 Apr 2006 20:11:20 GMT, mk <kal*@dspia.*comdelete> wrote:>On Thu, 06 Apr 2006 19:52:23 GMT, R.Lyons@_BOGUS_ieee.org (Rick Lyons) >wrote: > >>On 6 Apr 2006 08:32:45 -0700, "Brian Neunaber" <neunaber@gmail.com> >>wrote: >> >>>I can only speak within my area of professional expertise, which is >>>professional audio; and admittedly this is a small area within the >>>realm of DSP. That said, IIR filters are still used far more >>>frequently than FIR. I can think of a few reasons off the top of my >>>head: >>>1. IIR filters can be easily designed such that they have an analog >>>counterpart, with which the user is familiar. >>>2. IIR filters are more easily adjustable in real-time. >>>3. IIR filters are more efficient at low frequencies (< ~0.1*fs), >>>where much of audio processing takes place. >>> >>>Brian Neunaber >> >>Hi Brian, >> >> Looking at your Item# 2, the author of the article >>that I'm reviewing states that IIR filters are "difficult, >>if not impossible" to use for adaptive filtering. >> >>Is he exaggerating the difficulty in using IIR filters >>for adaptive filtering? > >I have done quite a bit of adaptive filtering work with FIRs. They are >extremely easy to get to work and always stable. IIRs have been >certainly difficult to use for adaptive filtering because they can be >made unstable inadvertently. But there has been a recent upsurge in >IIR adaptive filtering research and it is certainly doable. Difficult >yes but definitely not impossible, no where near impossible actually. >And if you consider the amount of hardware you're saying (low power is >the order of the day) it's certainly worth the effort.While nowhere near the rest of you guys, I have certainly constructed a few adaptive IIR filters, but instead of using the traditional type 1/2 forms, I used a "state variable" form - modeled on a traditional analog state variable filter, and described by Hal Chamberlin in a classic text on electronics in music decades ago (can't remember the name). In some common forms of this filter you adjust the frequency and damping ratio independently, which makes it ideal for adaption or modulation. And although the SVFs suffer all the same precision limitations as other forms, at least they don't need any coefficients related to w^2, so can be coerced into working at quite low frequencies. Tony (remove the "_" to reply by email)
Reply by ●April 8, 20062006-04-08
robert bristow-johnson wrote: ...> Tim knows about that DC blocking trick and i remember Tim improved upon > it, making it 2 instructions per sample (with the right pipelining) > reducing it from 3 which i never thought could ever be done. i'm still > impressed. (i.e. Tim made a permanent impression on me with that, and > if Grant wants to, we should update the trick at dspguru.com .)Please do. I'm sure Grant would be delighted too. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●April 12, 20062006-04-12
(Jumping in late.) In my little corner of the audio world, IIR filters are still extremely popular. One reason is that they need to be updated by users in real time. This is much simpler with IIR--compare RB-J's cookbook equations vs. running an FIR design tool! Another is that the products are often replacing analog gear, so it is a natural fit. -- Jon Harris SPAM blocker in place: Remove 99 (but leave 7) to reply "Rick Lyons" <R.Lyons@_BOGUS_ieee.org> wrote in message news:44344259.337998187@news.sf.sbcglobal.net...> > Hi Guys, > I was asked to review a potential article > for the IEEE Sig. Proc. magazine. In that > article the author implies that IIR (recursive) > filters aren't as popular nowadays as they were in > the past (say 10-20 years ago). > > Now I'm no IIR filter designer, so I need your > opinions. Aren't IIR filters still as popular > now for audio signal processing as they were > 10 years ago? > > Thanks guys, > [-Rick-] >
Reply by ●April 12, 20062006-04-12
in article Eqf%f.13090$gy2.4685@trnddc08, Jon Harris at jon99_harris7@hotmail.com wrote on 04/12/2006 18:45:> (Jumping in late.)... good to see you back, Jon. it's been about 2 weeks. -- r b-j rbj@audioimagination.com "Imagination is more important than knowledge."
Reply by ●April 13, 20062006-04-13
"robert bristow-johnson" <rbj@audioimagination.com> wrote in message news:C0630335.135E9%rbj@audioimagination.com...> in article Eqf%f.13090$gy2.4685@trnddc08, Jon Harris at > jon99_harris7@hotmail.com wrote on 04/12/2006 18:45: > >> (Jumping in late.) > > ... > > good to see you back, Jon. it's been about 2 weeks. > > -- > > r b-j rbj@audioimagination.com > > "Imagination is more important than knowledge."Thanks. It's been a combination of traveling and busy times.
Reply by ●April 13, 20062006-04-13
"Rick Lyons" <R.Lyons@_BOGUS_ieee.org> wrote in message news:44344259.337998187@news.sf.sbcglobal.net...> > Hi Guys, > I was asked to review a potential article > for the IEEE Sig. Proc. magazine. In that > article the author implies that IIR (recursive) > filters aren't as popular nowadays as they were in > the past (say 10-20 years ago).Hi Rick, this doesn't address your question directly, but from a reviewer's standpoint, you should tell the author(s) to qualify that statement. They should give a citation, or describe in more detail what they mean. For instance, they should state the occurence of an IIR keyword in published articles (IEEE trans on S P for instance) each year for the last 20 years or something like that. I don't think there is an EDICs number for IIRs or FIRs. Broad/vague statements about what is "popular" should be challenged. Cheers, bob PS of course, if it is just "implied" and you were just starting a discussion, then please disregard this post. :)
Reply by ●April 14, 20062006-04-14
On Thu, 13 Apr 2006 17:08:47 -0600, "R.G. Stockwell" <no@email.please> wrote:>"Rick Lyons" <R.Lyons@_BOGUS_ieee.org> wrote in message >news:44344259.337998187@news.sf.sbcglobal.net... >> >> Hi Guys, >> I was asked to review a potential article >> for the IEEE Sig. Proc. magazine. In that >> article the author implies that IIR (recursive) >> filters aren't as popular nowadays as they were in >> the past (say 10-20 years ago). > > Hi Rick, >this doesn't address your question directly, but from >a reviewer's standpoint, you should tell the author(s) >to qualify that statement. They should give a citation, >or describe in more detail what they mean. >For instance, they should state the occurence of an IIR >keyword in published articles (IEEE trans on S P for instance) >each year for the last 20 years or something like that. >I don't think there is an EDICs number for IIRs or FIRs. > >Broad/vague statements about what is "popular" should >be challenged. > >Cheers, >bob > >PS of course, if it is just "implied" and you were just starting >a discussion, then please disregard this post. :)Hi Bob, Thanks much for your sensible advice. [-Rick-]
