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Questions tagged [filter-design]

Fiter design is the process of designing a filter.

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Confusion regarding a library of Digital Signal Controller

I'll be using a NXP DSC with 56800Ex core and my aim is to implement a Elliptic IIR Filter in it. The User Reference Manual of the 'General Digital Filters Library' (which is available here) has ...
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1answer
6k views

Filter design with zero - pole placement method

I have some question for you about Filter design. Α. Calculate the transfer function in order to stop the frequency of $300\textrm{ Hz}$ for sampling frequency at $12\textrm{ kHz}$. Use the zero – ...
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2answers
1k views

highpass filter design in Matlab

I hope to design 1st order highpass filter from transfer function. In the example of 1st order lowpass filter, I first get the coefficients of numerator and denominator in the variable 'b' and 'a'. In ...
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2k views

FIR filter design in matlab using Kaiser window (using 'fir1' and 'designfilt')

Here are the specs for FIR filter using Kaiser window. ...
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2answers
162 views

Filter design to realize Cauchy product

I come from Computer Science so please pardon for my possibly wrong terminology. I need to design a filter which has coefficients $$h_0, h_1, \ldots, h_n, \ldots \quad\text{such that}\quad h_0 > ...
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1answer
65 views

Filters using equiripple approximations (different from type I lowpass)

In Oppenheim & Schafer's Discrete-Time Signal Processing, only type I lowpass filters are explained in detail in the chapter "Optimum Approximations of FIR filters". I want to know what happens ...
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1answer
1k views

How to implement bandpass filter on complex valued signal?

I am using Scipy to implement bandpass filter but it assumes that positive normalized frequency is passed but I & Q samples range from [Fc-Fs/2,Fc+Fs/2] where Fs is sampling frequency & Fc is ...
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3answers
623 views

How to Design Nonlinear Phase FIR Filter?

I've recently encountered a rather clever low-pass filter that appears to have been designed to sacrifice uniform group delay in the pass-band to get better frequency response relative to the filter ...
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1answer
8k views

High-pass filter in Python (Scipy)

This code is taken from a pitch detection algorithm. It is called before pitch detection to remove low-frequency noises. ...
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1answer
55 views

Latency handling at filter output

In MATLAB, latency at the start of the output of a filter can be handled by discarding those bits and starting the signal where the latency ends. but how can the garbage value at the end be handled?
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1answer
222 views

FIR filter design with flat passband but equi-ripple stop-band

I am looking for a lowpass FIR filter with flat passband but equi-ripple stopband. In other words, it likes Chebyshev_filter Type II except that it is FIR instead of IIR. Linear-phase is preferred. ...
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2answers
313 views

How to add group delay?

I was confused about the value of group delay, I am not sure whether my opinion is correct. For example, if I want to add a group delay of $0.25$ time units to a zero-phase signal, does it mean that I ...
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1answer
213 views

FIR Filters - Type 3

So I understand that a type 3 filter is not suitable for a highpass filter design, but is there any reason why it isnt suitable for a lowpass filter? So ultimately, can a type 3 linear-phase FIR ...
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1answer
138 views

IIR filtering vs IFFT filtering by zero binning and making bandpass IIR filters with high sample rates?

I am having some issues making thin IIR filters that work at the sample rate of my data and was wondering if there is a way to improve my method? I am also curious about the deficiencies in using the ...
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2answers
3k views

Why would one use a Hann or Bartlett window?

Suppose we're designing a low-pass FIR filter, and I want to use one of these three windows: Bartlett, Hann or Hamming. From Oppenheim & Schafer's Discrete-Time Signal Processing, 2nd Ed, p. 471:} ...
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0answers
310 views

Filter image in Fourier space imaginary components after ifft (R)

I want to high-pass filter an image in Fourier space. It works but the retransformed image has an imaginary part, what shouldn't be the case http://math.stackexchange.com/questions/867337/how-to-...
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1answer
272 views

Filtering White Noise to Generate Harmonic Signal

I have studied convolutions and filters a long time ago. Today, I am trying to review the basics using some notes of mine, but I am finding difficult to solve easy problems. Since I don't have ...
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1answer
201 views

Parameters of Butterworth filter that approximates the amplitude response of a Gaussian filter?

For a given narrowband Gaussian filter with a specific central frequency and filter width, I need corners of a bandpass Butterworth filter whose amplitude response is close enough to the Gaussian ...
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0answers
60 views

Is there a tool for automatically converting filter implementation forms?

I am looking for alternate tools that will automatically convert filter implementation forms (or signal flow network diagrams in general) to simplest or alternate forms; for example for going between ...
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1answer
244 views

Why low-pass FIR Equiripple filter is designed with 3 dB of ripple in the pass-band and at least 60 dB of attenuation in the stop-band?

Please tell me, why low-pass FIR Equiripple filters are designed with 3 dB of ripple in the pass-band and at least 60 dB of attenuation in the stop-band and not other values ? I want to know are ...
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1answer
379 views

Rectangular or trapezoidal signal filtering. Beginner

I have the following signal: I know, that there are 2 states ('High' and 'Low') in my real signal. I need to convert my signal to the sequence of these states (Low from 2 to 5 second, High from 5.5 ...
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1answer
596 views

Eigenfilters in Matalb [closed]

I have to implement an eigenfilter for an arbitrary frequency response in MATLAB. I have this algorithm: $N$ - order of the filter $M = N/2$ $c(\omega) ...
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3answers
463 views

What's the use of the ripple in the Equiripple method and their effect in the filtering process?

I read about the design methods of FIR filter which are: windowing method, sampling frequency method and Equiripple method. And I don't understand the use of the ripple in the Equiripple method and ...
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2answers
4k views

Low pass vs band pass filter

I've been reading some EEG papers where the authors use a bandpass filter at, say, 1Hz and 30Hz. I've also seen some accelerometer papers where they bandpass at 0.5Hz and 10Hz What is the difference ...
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2answers
370 views

what is the suitable design Method to the filter?

hi i'm going to design a low pass FIR filter for an EEG signal for the detection of eppileptic siezure and i want to know what is the suitable design Method to the filter? i need this FIR filter just ...
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0answers
172 views

Software implementation recipe of cascaded Biquad IIR filter

I have been given the task of measuring the performance of Biquad IIR filters on a new CPU that we are evaluating. What I know is that the Biquad filters can be cascaded to form higher order filters. ...
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1answer
687 views

Low pass FIR filter for EEG signal

I'm trying to do Analysis of EEG Signal for the Detection of epileptic seizure so in the pre-processing of the EEG signal I use a low pass FIR filter ...
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2answers
2k views

Root raised cosine pulse shaping filter

What are disadvantages of root raised cosine pulse shaping filter in digital communications and why does it need to be improved? Links: Square Root Raised Cosine Fractionally Delaying Nyquist ...
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1answer
114 views

MATLAB, error while trying to implement a Designed Filter object

I am using the Digital Filter with properties in MATLAB. I have defined the filter object filt(1) as: ...
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0answers
24 views

Which filter to use for data with high amount of errors?

I have the following data collected from a heart rate sensor. The data is in bpm vs. milliseconds. All the data points below 80 is incorrect (errors/noise). When it plummets below 80, it's because ...
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3answers
4k views

FIR Filter design: Window vs Parks-McClellan and Least-Squares

Are there any advantages to use a window approach over Parks-McClellan (further abbreviated here as PMcC) or Least Squares algorithms for FIR filter design of a low pass filter? Assume with today's ...
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2answers
4k views

Filter Order Rule of Thumb

Is there a rule of thumb for calculating the approximate filter order of a FIR/IIR based on passband vs sample rate? I seem to remember reading about it once in Undergrad. I'd think you could make a ...
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1answer
228 views

Resonance circuit peak filter with unity stopband in MATLAB

I would like to insert a filter with an resonant filter characteristic of a realistic mechanic oscillator. I need to apply it in the time domain, e.g. with a function such as ...
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2answers
1k views

How to choose the size of a Laplacian of Gaussian kernel for filtering images fast?

I am filtering an image using a Laplacian of Gaussian (LoG) kernel. The kernel dimensions are the same as the image. The filter operation takes very long to complete. How can I speed this up while ...
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2answers
44 views

Max useful filter tap count for given fixed point bitwidth

I have a 10 bit ADC sample stream in which I would like to apply a digital band pass filter. Is there a theoretical filter tap count that would define the threshold of "usefulness"? I guess my ...
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2answers
5k views

What is the difference between a lag filter and “PI” control?

A lag filter/compensator has the form $$G_c(s) = \frac{s+z}{s+p}$$ with $-z < -p < 0$. In practice, the effect of lag compensation in feedback control is to increase the DC gain of the open-...
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1answer
217 views

Interpolating and Decimating CIC filter based on sinc function

How to realize a sinc function using CIC filter for decimation and interpolation ??? Can I combine interpolation and decimaton methods inorder to get the complete response of a sinc function???
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97 views

Can picking an inappropriate roll-off frequency for a digital filter just alias the roll-off value?

I believe a related question is asked here, but my question deals more with what filter is realized if one fails to consider design parameters relative to sampling rate. In designing an IIR filter we ...
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1answer
658 views

Inverse a frequency response

I haven't recorded a precise impulse response, but I have carefully written the attenuation/boost of a recording chain for every third of octave: ...
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1answer
181 views

Highly damped IIR/FIR digital filter

I want a highly damped highpass filter (damping of at least $2$), with a cutoff somewhere around $1\textrm{ Hz}$ ($51.2\textrm{ Hz}\quad f_s$) How do i go about designing the filter with adequate ...
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2answers
716 views

How to know the filter order

Could anyone explain to me how can I know the filter order based on algorithm? For example: $y[n] = \frac12 x[n] – x[n–1] + \frac12 x[n–2]$ has order filter 2. $y[n] =2 x[n] – x[n–1] + y[n–1]$ has ...
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1answer
846 views

Matched Filter BER vs SNR curve does not match the theoretical curve [closed]

I am creating a matched filter using filter command. The coefficients are also generated in another file using sigma delta modulator these are ternary coefficients (+1,-1,0). I have generated 1 and 0 ...
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1answer
683 views

Inverse $z$-transform of a transfer function in MATLAB

I have designed a Butterworth highpass filter (HPF) of 4th order with cutoff frequency high enough to give a gain of $3$ at high frequencies. I want to find the inverse $z$-transform using MATLAB. <...
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1answer
418 views

First order Wiener–Hopf filter design

Consider a random process with auto-correlation function: $$r_{\rm dd} [k] = \beta^{\lvert k \rvert}\quad\text{where}\quad 0 < \beta < 1. $$ Suppose also that the observation is: $$ x[n] =...
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1answer
229 views

Filtering everything outside 20 - 20000 Hz

With an audio .wav file (sampled at 44.1 or 96 Khz), I would like to filter out everything outside the 20 - 20000 Hz range. I tried a Butterworth bandpass filter and there were unstability issues, ...
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1answer
361 views

python rewrite lfilter (iir) with for

It's a beginner question, but useful to users from python - signal.lfilter, I was using lfilter from Find reverse one pole ...
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2answers
407 views

Find reverse one pole lowpass filter

I need to find a filter that revert the one pole filter of the current signal, a function using Python (or MATLAB) scipy.signal.filtfilt or ...
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0answers
471 views

How to implement a time-varying filter?

I'm working on a 10-second sound, sampled at 44.1 khz. I want to do filtering, and have a desired EQ (equalization) curve that varies over time, as suggested here (here $f0=250\ Hz$) How to ...
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0answers
179 views

Zero STFT bins (and not FFT bins)

Filtering by taking FFT, zeroing bins, and inverse FFT is a bad idea, as discussed here. But what about: take a STFT, (i.e. multiply the input signal by moving window function, and take FFT) zero ...
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1answer
117 views

Laplace transform of averaging operator

I am studying dc-dc converter now. I got a problem with Laplace transform of the averaging operator as in the image below. Can anyone help me derive the Laplace transform result $G_{av}(s)$ as in the ...