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Questions tagged [filter-design]

Fiter design is the process of designing a filter.

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1answer
291 views

Trying to apply Parks-McClellan optimal FIR filter design

My goal is to apply the Remez exchange algorithm in R to design an FIR band pass filter for a specific frequency window. The question is not supposed to be referring to R of course but about how to ...
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1answer
540 views

Rate of fall of sidelobe level

Anyone can explain me about how measure side lobe roll-off rate of kaiser window from Spectrum in matlab where side lobe roll-off rate is the asymptotic decay rate, in decibels per octave of frequency....
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0answers
475 views

Doppler shift using PLL

I am trying to apply phase lock loop to calculate phase shift due to doppler effect and finally calculate the doppler frequency($\Delta f$). I am assuming that the received wave is of the form, $r(t) =...
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4answers
2k views

Digital Anti Aliasing Filter For Waveform Band Limiting

I am working on some waveform generation software and I am trying to figure out what the best type of filter would be to use a an Anti Aliasing filter for my algorithm. I am generating my waves in a "...
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1answer
290 views

Why multiplying frequency kernel with sinusoid results shifting frequency domain

I am having great time while reading "The Scientist and Engineer's Guide to Digital Signal Processing" book. In "Chapter-14 Introduction to Filters" author indicates we can create high pass filter ...
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1answer
693 views

Low Pass FIR Filter [closed]

I want to design FIR low-pass filter with the following specifications: Cut-off frequency: 200 Hz Order: 20 Sampling frequency: 1000 Hz what should be ...
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1answer
66 views

Speaker Recognition

How can you filter out a person's voice from a group of people talking? We have a sample of each person's voice from the group, and the sample of the entire group talking at once. Both samples are ...
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1answer
197 views

Filter design with 8-tap latency on recursion

I'm curious about the feasibility of designing a noise shaping filter (but might generalise to any recursive filter) with the constraint that the most recent output samples aren't available for ...
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1answer
133 views

Given input and output time series, obtaining filter design

Say I have 5 minutes of input and output audio. One method I know is to do FFT on windows from input and output. Then divide FFT output into bins and find average energy in various bands for all the ...
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2answers
840 views

Continuous-time mathematical formula for deconvolution filters

I have an elementary function $p:\mathbb{R}^2\rightarrow\mathbb{R}$ which (locally) represents an image. It's a polynomial, and its the result of the following 2D convolution: $$p=f\star G\star \...
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2answers
1k views

Design Filter Banks for every 100 Hz

I need to study a wave file for every 100 Hz. However, I dont know how can I design filer for each 100 Hz. Let's say 0-100 Hz, 100-200 Hz, ... , ((fs/2)-100) _ (fs/2) Hz. Is it any MATLAB code for ...
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0answers
94 views

question about the frequency of Gabor filters

The Fourier transform of 2D Gabor filters is shown below: F is the radial frequency of the Gabor functions. Another parameter Fm is denoted as highest central frequency. Fr is the constant frequency ...
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1answer
383 views

Bireciprocal lattice wave digital filter

I have posted this question "Electrical Engineering", but this seems a more appropiate place. I am trying to model a bireciprocal Cauer filter in LTspice but I don't get the expected results. More ...
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2answers
678 views

Bandpass Filter window length: filter “in phase” with sinusoidal input

Say you have a bandpass filter and you place it on 40 discretely sampled points from a sinusoid with a period of 40. Why is the bandpass filter (green curve on the image) only "in phase" with the ...
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1answer
2k views

fir filter - mean delay and snr from difference equation?

I'm trying to get my dsp sea legs a bit, and am trying to complete a problem that asks for the mean delay and expected SNR boost for a given difference equation: y[n] = (x[n] + ... + x[n-N+1])/N I'd ...
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1answer
792 views

Design $ {L}_{2} $ Norm Optimal Infinite Impulse Response (IIR) Filters

It is widely known that matching a FIR filter of fixed length to a band model is an unconstrained QP-problem. The MATLAB function firls() implements a solution to ...
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3answers
2k views

Digital filters with more zeros than poles

I am having trouble wrapping my head around digital filters with different orders of numerator and denominator. Let me know if any of these points is wrong: All (digital or analog) transfer ...
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1answer
1k views

How can I detect if a filter is FIR or IIR according to impulse response graph?

I have the following two graphs but I don't know how to recognize from the graph if they are IIR or FIR! Can you please guide me through? P.S.: Does MATLAB have a function to detect if an impulse ...
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1answer
129 views

Correction of a signal through a transmitter

I am inquiring as to a practical way to solve a problem I have. Basically, I need to transmit a signal, $x[n]$, through a seismic transmitter. (It will go through a D/A, etc). The transmitter that ...
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1answer
477 views

DC component of a discrete filter

I know that many books and papers talk about the DC offset/DC component of a filter. How do we define the DC offset mathematically, for the case of discrete filters?
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1answer
6k views

Bandpass butterworth filter frequencies in scipy

I'm designing a bandpass filter in scipy following the cookbook. However, if I decrecrease the filtering frequencies too much I end up with garbage at high order filters. What am I doing wrong? ...
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0answers
62 views

Low pass butterworth filter is distorting [duplicate]

my low pass filter keeps distorting and I'm at a loss to explain why. It calculates the correct coefficients, but distorts everything. The code is as follows. It's driving me mad. What's weird is my ...
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2answers
6k views

gabor filters for digital image processing

For the application of Gabor filters in feature-based (e.g. lines and edges in images) digital image processing, it is desired that the DC component is 0. Why is this so? What effect does it have ...
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3answers
12k views

What is a window function in DSP and why do we need it?

When designing digital filters we start off with FIR and IIR. Later on we talk about window functions e.g Kaiser and Hamming windows. I do not understand why we need so many type of window functions ...
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3answers
4k views

A good textbook for designing signal filters

Since a couple of months ago I started being actively involved in the area of control of dynamical systems. In most cases, designing a controller for a given dynamic system will require the ...
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0answers
301 views

Design Nonlinear (Arbitrary) Phase FIR Filter using Iterative Reweighted Least Squares (IRLS)?

How would you use the MATLAB function below to create a FIR filter with a custom magnitude and phase response? It is from the Statistical Modeling and Inference MATLAB Toolbox ...
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1answer
823 views

wiener filter (non-causal) calculating covariance matrices

I'm learning about the Wiener filter, and I'm working on my own implementation. I'm starting out with the non-causal filter, and I need to calculate some covariance matrices. If the signal is assumed ...
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1answer
516 views

Analytical Calculation of the Impulse Response of an Arbitrary Filter

This is a rather general question. Suppose I have an arbitrary filter, $F$, defined in the Laplace domain; $$ F=k\frac{\prod_i (s+z_i)}{\prod_j(s+p_j)}. $$ How do I calculate the impulse response of ...
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2answers
2k views

Convolution theorem with a kernel smaller than the image

Suppose that I need to apply a convolution filter to an image. I want to do it by using the convolution theorem so I compute the kernel for the size of the input image to later calculate fft's and ...
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0answers
141 views

Relationship between fractional delay coefficients and frequency?

Some background: I am putting a sig-gen signal through an ADC, into an FPGA where I can modify it, out a DAC and up to a SpecAn. All that works fine. I am experimenting with fractional delay filters,...
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1answer
271 views

Filter pixels with respect to specific wavelength frequencies

I'm not sure if this is possible, but let's say you had access to the original raw sampled digital pixels from a sensor, captured with nothing between the sensor and the lenses, i.e. Anti aliasing ...
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1answer
766 views

Why is state-space representation more numerically stable than zeros-poles representation?

Matlab documentation says things like: For high order filters, the state-space form is the most numerically accurate, followed by the zero-pole-gain form. The transfer function coefficient form is ...
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4answers
2k views

FIR filter design by the Fourier transform method

I am having some problems understanding how the Fourier transform method is used to determine the FIR filter. As far as i have understood, you start by using the ideal impulse reponse for the ...
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1answer
2k views

Realisation of a passive RC low pass filter

I have an unusual low-pass filter problem that I would like to realise with a passive RC network (Note 1). It's easy enough to find prototype filters for passive RLC networks, or for the various ...
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4answers
5k views

How detect and filter noise from signal

This is the spectrum of the signal: And this is the signal: On the FFT spectrum you can notice the high amplitude peaks and I think these frequencies are the main ones in the signal: I think ...
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1answer
184 views

Designing FIR filter

I'm asked to design FIR filter, an ideal low pass filter. I'm given with pass band frequency (wp) and stop band frequency (ws). Now, I have to choose Ns points from stop band and Np points from pass ...
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2answers
99 views

What are the tradeoffs for more coefficients for fractional delay filter?

Is there a rule of thumb for how many coefficients to choose for a fractional delay filter? I figure there might be a trade off based on the signal frequency as well as my sample rate (this is ...
4
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1answer
1k views

How to determine Hilbert coefficients

I want to take a real signal on my FPGA and create a complex one. I have FIR core implemted for a Hilbert Transform, and Xilinx's datasheet on it shows coefficients of: (-819,0,-1365,0,-4096,0,4096,0,...
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2answers
2k views

28-Band Graphic Equalizer in Matlab

I'm trying to design a MATLAB audio player that includes something like a 31-band equalizer. Right now I have the filters working by using the FIR1() function to ...
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3answers
2k views

Filtering with STFT

I have sucessfully implemented a STFT (+inverseSTFT with perfect reconstruction of original signal, with overlap add, etc.) in order to work on audio files. Using this STFT / iSTFT framework, I have ...
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1answer
23 views

How to detect if the given signal is Data or Clock signal type?

I have the edge information of the signal. I need to find if it's a Clock or Data type signal without iterating through all the points in edge vector... Please provide your valuable inputs
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1answer
295 views

A little bit better than zeroing bins in order to filter

The topic of zeroing frequency bins before IFFT has been discussed here : Why is it a bad idea to filter by zeroing out FFT bins? It was very helpful to understand why it is a bad idea. What do you ...
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1answer
2k views

Design a comb notch filter when sampling rate is not an integer multiplicative of the cutoff frequency

Let's say I have a signal sampled at 976 Hz and I want to remove network interference noise, i.e. 50 Hz and all the harmonics. Is it possible theoretically to design a comb filter to do that? I have ...
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2answers
149 views

How to do a spectral fade out?

I'd like to do a fade out of a sound in a few seconds, but in a "spectral way", with a special curve : (here x-axis is time, y-axis is frequency from a few hz to 20khz). All the part "to be removed"...
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1answer
700 views

Synthesize Digital Filter with Arbitrary Frequency-Response

fdesign.arbmagnphase is a MATLAB built-in function that will create a filter that best fits the frequency-response that it is given. I'd like to implement a similar function in Python. What ...
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0answers
143 views

Causal bandstop filter

I have a vector of zeros and ones with length ~2000. I need to detect and filter out the once, that appear periodically. There may be none to 3 such periodic signal's components. Typical periods are ...
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0answers
2k views

Difference between state space and transfer function model response (in Simulink)

Why I get a different response from the same system (e.g. three phase inverter with LC filter) in state space form and in transfer function (Laplace) form when using the same PI controller values ($...
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1answer
406 views

Very first values of y[n] in an IIR filter

I use a simple biquad IIR filter : ...
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1answer
154 views

Guess the frequency response of a filter with little information

I have a processing unit that does a nice EQ filtering on soundfiles. The only thing I can do is : I give the original .wav file, and the processing unit gives me back the filtered .wav. I have no ...