Hello, I am searching for examples (reference - papers, books) of narrow-band peak-notch filters pairs design having complementary frequency characteristics. By "complementary" I mean a characteristic of notch having -40..80 dB at some f0 frequency, 0dB in others, and peak filter having floor at -40..80 but 0dB at f0. Cascade connection of both should give -40..80 dB horizontal line. Such a pair are used in application where we need to insert some control signal at some not important, or not used frequency sub-band. Kind regards Roman
Complementary narrow-band peak-notch filters pair design
Started by ●May 3, 2016
Reply by ●May 3, 20162016-05-03
On Tuesday, May 3, 2016 at 6:13:13 AM UTC-7, roman rumian wrote:> I am searching for examples (reference - papers, books) of narrow-band > peak-notch filters pairs design having complementary frequency > characteristics.Maybe I miss the point, but I think if you take one, say f(x), and compute 1-f(x) (scaled appropriately) you should get what you want. In more usual cases, this allows for low-pass and high-pass complementary filters, but it should work fine for peak/notch, too. Well, it does require careful design of the filter in the first place, but you can't get away from that. The notch filter has to be very close to 1 away from the notch, which might otherwise not be a requirement.
Reply by ●May 4, 20162016-05-04
On Tuesday, May 3, 2016 at 9:13:13 AM UTC-4, roman rumian wrote:> Hello, > > I am searching for examples (reference - papers, books) of narrow-band > peak-notch filters pairs design having complementary frequency > characteristics. > By "complementary" I mean a characteristic of notch having -40..80 dB at > some f0 frequency, 0dB in others, and peak filter having floor at > -40..80 but 0dB at f0. > Cascade connection of both should give -40..80 dB horizontal line. > Such a pair are used in application where we need to insert some control > signal at some not important, or not used frequency sub-band. > > Kind regards > > Roman
Reply by ●May 4, 20162016-05-04
On Tuesday, May 3, 2016 at 9:13:13 AM UTC-4, roman rumian wrote:> > I am searching for examples (reference - papers, books) of narrow-band > peak-notch filters pairs design having complementary frequency > characteristics. > By "complementary" I mean a characteristic of notch having -40..80 dB at > some f0 frequency, 0dB in others, and peak filter having floor at > -40..80 but 0dB at f0. > Cascade connection of both should give -40..80 dB horizontal line. > Such a pair are used in application where we need to insert some control > signal at some not important, or not used frequency sub-band. >Roman, other than the constant gain difference, why doesn't the "Peaking EQ" in the Audio EQ Cookbook http://www.musicdsp.org/files/Audio-EQ-Cookbook.txt fit your requirement? r b-j
Reply by ●May 4, 20162016-05-04
On Tue, 03 May 2016 17:57:44 -0700, herrmannsfeldt wrote:> On Tuesday, May 3, 2016 at 6:13:13 AM UTC-7, roman rumian wrote: > >> I am searching for examples (reference - papers, books) of narrow-band >> peak-notch filters pairs design having complementary frequency >> characteristics. > > Maybe I miss the point, but I think if you take one, say f(x), and > compute 1-f(x) > (scaled appropriately) you should get what you want. > > In more usual cases, this allows for low-pass and high-pass > complementary filters, but it should work fine for peak/notch, too. > > Well, it does require careful design of the filter in the first place, > but you can't get away from that. The notch filter has to be very close > to 1 away from the notch, which might otherwise not be a requirement.I think there's a lot more ways to get notch and peak filters than there are to get ones that necessarily do what you want. Start with one denominator, then find a pair of numerators that work right... -- Tim Wescott Wescott Design Services http://www.wescottdesign.com
Reply by ●May 4, 20162016-05-04
On 3.5.16 16:13, roman rumian wrote:> Hello, > > I am searching for examples (reference - papers, books) of narrow-band > peak-notch filters pairs design having complementary frequency > characteristics. > By "complementary" I mean a characteristic of notch having -40..80 dB at > some f0 frequency, 0dB in others, and peak filter having floor at > -40..80 but 0dB at f0. > Cascade connection of both should give -40..80 dB horizontal line. > Such a pair are used in application where we need to insert some control > signal at some not important, or not used frequency sub-band. > > Kind regards > > RomanHave you considered that the bandwidth of the control signal must be compatible with the notch width? A steep notch will ring in a way similar to an equally steep peak. -- -TV
Reply by ●May 6, 20162016-05-06
Hi Robert, W dniu 2016-05-04 o 16:21, robert bristow-johnson pisze: (...)> Roman, other than the constant gain difference, why doesn't the "Peaking EQ" in the Audio EQ Cookbook http://www.musicdsp.org/files/Audio-EQ-Cookbook.txt fit your requirement? > > r b-jyes, you are right, but sorry, I badly defined my need. I have a design method of such a filters pair, but need literature references for our new publication. BTW, your Cookbook is excellent, I used it many times - THANK YOU ! :-) Roman
Reply by ●May 6, 20162016-05-06
W dniu 2016-05-04 o 18:27, Tim Wescott pisze: (...) > I think there's a lot more ways to get notch and peak filters than there > are to get ones that necessarily do what you want. > > Start with one denominator, then find a pair of numerators that work > right... Thank you Tim. :-) Maybe this way ? notch: [num]= [1 -1.98288773985790 0.99999800000100]; [den] = [1 -1.98269143377535 0.99980001000000]; peak: [num] = [1 -1.98269143377535 0.99980001000000]; [den] = [1 -1.98288773985790 0.99999800000100]; ;-) Roman
Reply by ●May 6, 20162016-05-06
W dniu 2016-05-04 o 02:57, herrmannsfeldt@gmail.com pisze: (...)> Maybe I miss the point, but I think if you take one, say f(x), and compute 1-f(x) > (scaled appropriately) you should get what you want. > > In more usual cases, this allows for low-pass and high-pass complementary > filters, but it should work fine for peak/notch, too. > > Well, it does require careful design of the filter in the first place, but you > can't get away from that. The notch filter has to be very close to 1 away > from the notch, which might otherwise not be a requirement.Hermann, yes, you hit the point. As the notch is close to 1.0 the numerical precision and stability issue are the problem. Thank you. :-) Roman