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Questions tagged [filter-design]

Fiter design is the process of designing a filter.

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48 views

Convolution of a non-symmetrical window function by a cosine signal in the frequency domain

A have a time signal: The associated DFT spectrum of this signal: The time signal can be considered as a non-symmetrical rectangular window function multiplied by a cosine signal with a frequency $...
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54 views

What are the limitations of FIR filters?

I know that for type II FIR filter it adds a zero at $z=-1$ so it cannot design a high-pass filter. My question: what type of limitations the other types have (type I, III, IV)?
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Converting an equation for decay times/rates by frequency into a filter for Karplus Strong (waveguide) synthesis?

I've spent a lot of time building a modal guitar/string synth based on resonant bandpasses where there is one bandpass per mode. It's a nice method because it's very easy to tune each mode's frequency/...
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1answer
40 views

Real Fast Fourier Transformation (FFT) in 2D changes with changing the axes order

I am using Python to calculate the real FFT for a 2D array. I found that the real FFT function does not return an array with the same size as the input array, rather, it returns an array with the same ...
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1answer
84 views

Use recursive least square as an “actual” filter?

I am currently studying recursive least square (RLS) and as far as I understand, the setup is (for example) that we are given a process with uncertain parameters/noise and we want to adapt parameters ...
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33 views

To find the filter Co-efficients of the following equation

Given $y[n]=h_1[n]x[n]+h_2[n]x[n-1]+h_3[n]x[n-2]$ is an LTI system with unity gain at $\omega =0$ and zero gain at $\omega =\pi$. $h[n]\neq0$ .Also given that the system has a linear phase. Compute $...
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24 views

How to make signal smooth using filter?

I have measured the output of a mechanical system and obtained the signal shown at the attached image. I want to make it smoother by removing the chattering (I think it is called chattering). In order ...
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1answer
44 views

Is gradient vector of pole zero carry usful information?

Consider a transfer function (TF) with $n$ number of poles $(p_1,..p_n)$ and $m$ number of zeros $(z_1,..z_n)$. One can write the magnitude of the frequency responce of the TF in terms of poles and ...
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Bandpass Experiment: Weird graph! amplitude mismatch?

Why is this generic BP filter seem to magnifying amplitudes when I run it at lower sample rates? The bass range seems to 32 times louder at 1275 Hz (44.1 kHz / 32) than at 44.1kHz? Here is a graph of ...
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2answers
47 views

Where should I set my anti-aliasing filter corner frequency for this signal?

I have a Fourier transform of an arbitrary digital signal. The transform has For 1024 frequency bins. The magnitude plot of the first 100 is below, with no surprises in the unplotted 924 bins. Now, ...
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44 views

How do I interpret this block diagram correctly?

I am reading notes ahead of the class and have encountered this particular slide: While I completely agree with the first block diagram, I am at a loss trying to understand how the second block ...
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29 views

Wiener Filtering to perform minimum mean square estimation

As the Title suggests, I am trying to design a Weiner Filter for getting the lower bound on my LTE channel estimation algorithm. To give you a high level on the chain, First after generating the ...
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1answer
43 views

Are MATLAB function zp2tf() and tf2zp() are complementary or not?

I was under impression that given, pole, zero and gain the transfer function (filter coefficients b and a) is fixed. Therefore, ...
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1answer
54 views

How to smooth filter response?

I have a filter designed in matlab with the function cheby2( N, Rs, Ws, 'stop'). The filter would give nice frequency response with for a given parameter set when the filter order is 2 or 4 (N=4). But ...
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1answer
19 views

Bessel filters: linear passband phase characteristic only for low pass filters?

I've found a test (internet) from the contest to signal processing teacher and it has a question (true) or (false). I cant find any book or paper to argue this statement. Is it really true?
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40 views

FIR bandpass filter for complex baseband signals

I am DSP newbie and I need to apply a bandpass filter to the complex baseband signals of bandwidth 20MHz and sampling rate 61.44 MHz. Below is the octave code for the same and I have obtained ...
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1answer
33 views

How would I calculate the DC Gain for a Chebyshev Type 2 filter?

I'm currently working on an implementation of a Chebyshev Type 2 filter but the gain is all over the place when playing around with the order and ripple. I haven't found anything online but (as far as ...
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1answer
56 views

How to perform spectral inversion in the frequency domain to convert a low-pass filter into a high-pass filter?

To convert a linear-phase FIR low-pass filter into a high-pass filter with the same cut-off frequency, we can invert the sign of the low-pass filter's impulse response $h(n)$ and then add one to the ...
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How to design a filter with smoothness regularisation?

I am rather new to the DSP topic. However, I would like to filter a signal with lowest error and highest smoothness. Until now, I was using tikhonov regularisation inside batch regression with some ...
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Can Kaiser's formula be used to estimate the filter length of an FIR filter for all windowing methods?

I came across this problem while designing a FIR filter for given $\omega_p = 0.4\pi$ and $\omega_s = 0.6\pi$ along with the minimum stop-band attenuation $\delta_s$. I have worked out some examples ...
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59 views

Parallel equalizer, working for boosts but not cuts

I am trying to replicate the behaviour of a parallel equalizer. The approach is to use a parallel sum of bandpass filters like so: $Response = 1 + bandpass1 * (gain1 - 1) + bandpass2 * (gain2 - 1) + ...
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What is the meaning of these Fixed Point Properties e.g.CustomSectionInputDataType?

I was trying tom implement a Butterworth filter and i came across a example on Mathworks site which emphasizes to customize various terms related to the filter. Following are some of the terms i could ...
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53 views

How would one design a (quasi) linear phase adaptive notch filter for a single complex tone?

While IIR notch filters are attractive, I need to retain phase linearity at the filter output. I imagine that it's possible to use a standard IIR notch filter: https://www.researchgate.net/...
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Vary poles/zeros of digital IIR filter

Many applications that produce sound, such as software synthesizers, are able to apply a filter that varies with time, such as applying a low pass filter that varies with an LFO. I currently have a ...
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Interpolation FIR filter Remez design criteria

I want to upsample an audio signal by a factor of 8. The technique I was going to use was to upsample by zero stuffing and then interopolate using a low pass anti-aliasing FIR filter designed using ...
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1answer
39 views

Why does sampling frequency affect the filter results?

I have a big issue, basically my goal is to create a low-pass butterworth filter around 0-35Hz with a sampling frequency of 5000Hz. My Matlab code is ...
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3answers
97 views

Matlab IIR cheby2 bandpass, problems with Magnitude

I am trying to implement an IIR bandpass in Matlab. There are two things I don't understand. But first of all, let me post the code. ...
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2answers
36 views

Downsides of higher order filtfilt's

I understand that with a standard filter, higher order will yield sharper frequency selection at the cost of increased phase delay. However, with so-called zero-phase-distortion filters like that ...
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Avoiding transients during filtering: Padding or Gustafsson's method?

I'm pretty uneducated when it comes to filtering, more of a stats guy, but I have to bandpass some signals and after a bunch of reading today I understand that the ...
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Estimate peak bandwidth from adjacent STFT bins for notch filter

I am using STFT to extract a strong, frequency varying signal from a continuous set of digital samples. I am able to do this very successfully and am determining the peak bin using PSD and 50% overlap ...
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1answer
34 views

FIR Filter Type - MATLAB

A question about using fir1/fir2/firpm to design FIR filters in MATLAB. The first parameter is the 'filter order'. For my filter design I pass in 250 as this argument. However, when looking at the ...
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1answer
49 views

MATLAB fir2 - npt and lap

This might not be the right place to ask this, but I'm hoping someone can explain two of the arguments in the MATLAB fir2 function. It is a function for designing ...
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Signal attenuates after interpolation

So I'm designing all my interpolation filters to have unity gain at 0 dB. This results on my output signal to have a small amplitude. I was reading how to fix this and found this post Interpolation ...
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52 views

Ripples in filter

What are the uses of ripples in the filter design. We try to design a filter with least ripples but sometimes we design a filter to have 2 or 3 ripples. Why is it so?
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141 views

How would you interpret the pattern in this picture? (generated by re-sorting pixels based on their RGB value)

Was playing with some pictures and ran the ruby code below. The code reads an input image using the ImageMagick library, gets an array of pixels, re-sorts the pixels and then writes out an image with ...
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3answers
108 views

Reverse engineering a digital filter

I have 2 simultaneous signals that both are designed to measure eye movements. They are sampled at 250 Hz. We have 12 subject recordings. For 3 stable periods in each subject, we choose 256 points and ...
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54 views

CIC compensation filter and total response

UPDATE: New plot with properly scaled CIC comp response. I'm studying about CIC filters for interpolation/decimation and I'm reading about CIC compensation filters due to CIC filters not having a ...
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1answer
45 views

Length of Matlab Raised Cosine Filter Output Complex Vector

If I instantiate in Matlab a filter, a vector, and use them in the following way: ...
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1answer
36 views

MATLAB Convolution

I am designing an IIR notch filter using pole-zero placement method. I am trying to convolve the two zero locations using ...
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2answers
218 views

Numerically Stable IIR filter

I am making an IIR Filter and I am running into problems with stability with higher orders. The values go off to infinity as soon as it starts. So far, I've been using MATLAB to generate my filters ...
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1answer
51 views

2D Multi-scale dot enhancement filter based on Gaussian filter and Hessian matrix

I'm trying to implement an algorithm that enhance dot and line like structures based on Hessian matrix, the algorithm uses Gaussian filter with different scales before calculating the hessian matrix ...
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1answer
87 views

Low-Pass Filtering of not evenly sampled signal

I have a signal sampled unevenly over 1 million ns. the signal is sampled over 1GHZ clock and the samples are as the following: 0-100 ns - sample every 1 ns. 100-1000 ns - sample every 10 ns. 1000-...
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1answer
29 views

Is there any advantage on using a low span value in a RRC filter?

I know that in a RRC filter a high value of the span gives a better response, in the sense that the RRC filter response is more near to the ideal RRC filter response. However, would there be any ...
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2answers
133 views

Is There Any Filtering Technique with Element Wise Product Only Instead of Convolution?

Generally we apply a filter to reduce noise from signal. For example if the received signal is $S$ we would get a signal $Y$ with reduced noise applying a filter $W$ with the operation Y= convolution(...
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1answer
92 views

Jacobian Computation in Least Squares IIR Filter Design

Long time lurker and first time poster - but unfortunately I haven't had any joy untangling this on my own. I've been studying Mathias Lang's thesis, Algorithms for the Constrained Design of Digital ...
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1answer
83 views

Side Lobes in the Magnitude Response of a Low Pass FIR Filter

I have the impulse response (from the filter coefficients) of an FIR filter obtained from MATLAB's "interp" function using the command: [y, b] = interp(x, 5); % where b contains the interpolation ...
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37 views

Cascading filters at different sampling rates

We are currently designing a type 2 compensator $G_1$ (1 pole at the origin, 1 zero and 1 pole) to stabilize a power factor correction (PFC) circuitry. The crossover frequency is low - 2-3 Hz - and ...
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1answer
49 views

Criterion to choose length of an accumulator and product

I am designing an IIR filter with fixed-point arithmetic and I have to select the proper length for the accumulator and product. I would like to know a standard to follow in order to choose its length....
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3answers
219 views

How to determine if an IIR filter is causal or non-causal?

It may sound impractical, as only causal system are passively realizable, but what I am facing is a general statement made regarding recursive digital filters: for them to be stable, the poles should ...
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1answer
50 views

What should be my sampling frequency?

I have an accelerometer that I am reading the x, y, z values for m/s^2. I've written up my code in Python as follows. ...