60Hz Notch filter at 25kHz sampling rate?

Started by abradley1984 in comp.dsp11 years ago 22 replies

Hello, I have an ENG signal, sampled at 25kHz that has high mains interference that I want to remove. The problem is I need the surrounding...

Hello, I have an ENG signal, sampled at 25kHz that has high mains interference that I want to remove. The problem is I need the surrounding frequencies, maybe not 50-70, but I can't afford to sacrifice much more than this. The filter designs I've been looking at don't seem to be able to do this at such a high sampling rate. Any suggestions? Would downsampling help? Thank you in adva...


Linkwitz-Riley response not perfectly flat

Started by jungledmnc in comp.dsp10 years ago 18 replies

Hey guys, I did a digital crossover for audio using classical R'b'j biquads, it can have variable number of bands spilled between 20Hz-20kHz....

Hey guys, I did a digital crossover for audio using classical R'b'j biquads, it can have variable number of bands spilled between 20Hz-20kHz. Every band is processed using the same number of filters - lp, hp and allpass for phase-compensation. When 2 bands are too close enough, without allpass it is useless, it can create even 20dB peak/notch. With the allpass it is much better, but still it can ...


ANC with wrong reference signal

Started by AudioPhil in comp.dsp11 years ago 9 replies

Hi Guys, I work with a ANC for my studies, and I have the following problem: Algorithm: FxLMS with two weight factors scaling sine and...

Hi Guys, I work with a ANC for my studies, and I have the following problem: Algorithm: FxLMS with two weight factors scaling sine and cosine oscillators in order to synthesize an 'anti-vibration' to eliminate higher orders of a known reference signal which consists of pulses (like those that come from a tachometer) in a slightly coloured noise. (You see, this is an adaptive notch filter, F...


narrow band (notch?) filters at a range of frequencies

Started by Anonymous in comp.dsp11 years ago 13 replies

hi, i have two very noisy signals, and i am hoping to generate some sort of "diff" of the two signals in frequency space. so far, i...

hi, i have two very noisy signals, and i am hoping to generate some sort of "diff" of the two signals in frequency space. so far, i have computed a power spectral density estimate of each of the two signals. then i subtracted the PSD of one from the other (the idea being that frequencies where one has low power and the other high power, i should see a big difference... positive or negati...


ultimo dsp super filter

Started by Mac Decman in comp.dsp8 years ago 11 replies

I would like to design filter which has frequency frmo 0 hz to 1mHz with passband equal to all filters. I have dsp which is top notch and will...

I would like to design filter which has frequency frmo 0 hz to 1mHz with passband equal to all filters. I have dsp which is top notch and will do out of band processing. I would like to make sure all pass band is free from phase modulation so that no problems acure with my delicate process. Can some one help me with this problems. I hope every who contributes to this group has a great hol...


Sharp DSP notch filter

Started by Eeyore in comp.dsp10 years ago 83 replies

I am proposing to engage on a project regarding mains voltage 'purity' (and absence of ) with regard to audible clicks and pops in...

I am proposing to engage on a project regarding mains voltage 'purity' (and absence of ) with regard to audible clicks and pops in high-end professional and hi-fi audio equipment. Typical EMC filters operate in the RF band and are threfore no use to filter audio 'in band' noise that can travel through transformer interwinding capacitance etc. I have found some of the TI INA series that w...


remove 60 Hz noise

Started by zorgz in comp.dsp13 years ago 4 replies

Hi everybody i'm newbie in DSP, I'm writing an application in Java. My application does the following: Trace an ECG diagram, diagram...

Hi everybody i'm newbie in DSP, I'm writing an application in Java. My application does the following: Trace an ECG diagram, diagram is represented by an array of 2000 values, the signal duration is 4 secs, it's mean 500 points/second, so my frequency is 500Hz. Now my application must remove 60 Hz noise from diagram using notch filter. I dodn't know how to process exactely, but if i und...


Cascading filters with different sampling frequencies.

Started by Anonymous in comp.dsp14 years ago 14 replies

Hello, I have two filters, one designed for a sampling frequency of 16kHz and the other for a sampling frequency of 8kHz. The type and kind...

Hello, I have two filters, one designed for a sampling frequency of 16kHz and the other for a sampling frequency of 8kHz. The type and kind of filters (FIR/IIR, HP/LP/Notch) is irrelevant. I need to plot the overall transfer function of this cascaded pair. What changes do I have to make (in the 8kHz filter, I am assuming), if any at all, in order to cascade the two filters? Pointers to ...


Adaptive Notch filtering using FxLMS

Started by lightbearer in comp.dsp4 years ago 2 replies

I've been coding up a working MATLAB simulation on a Blackfin 533 using the 32 bit fractional data type (fract32). I have used FIR filters...

I've been coding up a working MATLAB simulation on a Blackfin 533 using the 32 bit fractional data type (fract32). I have used FIR filters to implement convolution to get outputs from different filter stages. I'm using look up tables created from MATLAB to simulate the algorithm internally on the processor. The LUTs consist of secondary path filtered white noise and a 30Hz sine wave also filtered...


speech recognition

Started by RichD in comp.dsp7 years ago 39 replies

http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2012/01/16/BU8C1MOO20.DTL He claims he can filter speech from background noise. I recall...

http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2012/01/16/BU8C1MOO20.DTL He claims he can filter speech from background noise. I recall discussing this possibility years ago. Someone said, these filters already exist. They do - they're notch filters! It's close to brain dead, believing that constitutes 'voice filtering'. Dr. Watts has been working on this for years, so I was wond...


changing the frequency of an IIR filter knowing only its coefficients

Started by Paul Auchon in comp.dsp13 years ago 2 replies

we are here in a case where only the coefficicents of the IIR filter are known. Is it possible to change the cutoff frequency of this filter...

we are here in a case where only the coefficicents of the IIR filter are known. Is it possible to change the cutoff frequency of this filter (which could be a notch filter for example, or something more complex) having only its coefficients (a0/a1/b1...)? 1- can any filter of any pole (2 to 16 and more) be transformed back into a pole-zero notation? If yes, would there be then any chance tha...


A little question about THD+N

Started by Clyde in comp.dsp12 years ago 11 replies

Hi, i wrote a little algorithm to measure the THD+N of a 1kHz sinus. The pattern i follwed is: y = original sinus; k = y * blackman-harris...

Hi, i wrote a little algorithm to measure the THD+N of a 1kHz sinus. The pattern i follwed is: y = original sinus; k = y * blackman-harris window z = notch(k) now, my question is: what's the right value? is it thd+n = rms(z)/rms(y) * 100 or thd+n = rms(k)/rms(y) * 100 ? (the first one is about half of the second one in every test i did) Thanks! -- Clyde


Magnitude response of linear predictor (interference cancellation)

Started by Eric Huay in comp.dsp6 years ago 6 replies

I'm trying to implement an interference cancellation using linear prediction. A block diagramtherefore is shown in [1]. The adaptive algorithm as...

I'm trying to implement an interference cancellation using linear prediction. A block diagramtherefore is shown in [1]. The adaptive algorithm as a LMS (least mean square)-algorithm. This works quite well! The overall system is something like notch-filter. How can I obtain this magnitude response of the overall system? Thank you and best regards Eric [1] http://goo.gl/UtAkgM


three DSP article

Started by Philippe Strauss in comp.dsp7 years ago 3 replies

Guys (Gals:), I've changed the domain of my website containing some article on DSP: http://www.strauss-acoustics.ch/ (previously...

Guys (Gals:), I've changed the domain of my website containing some article on DSP: http://www.strauss-acoustics.ch/ (previously www.philou.ch) contains : Pure javascript HTML5 canvas bilinear image interpolation Easy to read C Fast Fourier Transform (FFT) signal processing code FIR filter design experiment using the simplex method Zölzer-Boltze (ZB) peak/notch parametric EQ in


Top Notch Semiconductor Company calls for DFT Engineers

Started by Shilpa in comp.dsp14 years ago 16 replies

Hi Group, We are PriorityONE Consulting, a Human Asset Management company, run by IITians headquartered in Bangalore. We are serving big MNC...

Hi Group, We are PriorityONE Consulting, a Human Asset Management company, run by IITians headquartered in Bangalore. We are serving big MNC clients as well as small product development startup companies. We have High Technology companies like Google, Oracle, Intel, Adobe, Yahoo, Amazon, Nvidia, Kasenna, Andale, Pivotal as well as some of the latest companies coming to India like Target,...


Acoustic feedback cancellation

Started by Roman Rumian in comp.dsp12 years ago 3 replies

Hello friends, We are working on an Acoustic Feedback Cancellation system. The system must cancel the feedback tone before this (usually pure...

Hello friends, We are working on an Acoustic Feedback Cancellation system. The system must cancel the feedback tone before this (usually pure tone) becomes dominant or even audible. FFT methods (for the howling frequency detection and notch adaptation) developed by my friend seems to be too slow and acoustic howling becomes audible for about one second. The method could be speed up if ...


HPF/LPF symmetry

Started by jeff227 in comp.dsp13 years ago 9 replies

How come when I "spectrally invert" the coefficients of a LPF the resulting HPF frequency response is not symmetric? A Hanning Window FIR, for...

How come when I "spectrally invert" the coefficients of a LPF the resulting HPF frequency response is not symmetric? A Hanning Window FIR, for example, gives a flat passband, nice rolloff and slightly lumpy stopband. When I invert, the HP response looks like a "checkmark" with a flat passband, flat stopband and a notch at Fc (the corner frequency). It looks more like an elliptical filter ou...


Why some IIR filter methods can't be used for High Pass Filters?

Started by commengr in comp.dsp10 years ago 17 replies

Hello, I have a question that why can't some IIR filter design methods like Impulse Invariant & Approximation of derivatives be used (or have...

Hello, I have a question that why can't some IIR filter design methods like Impulse Invariant & Approximation of derivatives be used (or have poor response) as band-pass, notch and high-pass filters I think the reason for approximation of derivatives is that we can't go beyond fs/4 on the Z-plane, so high-pass is out. But what is the issue with band-stop and band-pass for a small pass-band...