Questions tagged [filter-design]

Fiter design is the process of designing a filter.

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819 views

removing vertical lines in grayscale images by thickness

Suppose we have a grayscale image that contains vertical lines. Now suppose that not all vertical lines are the same, some of them have different thickness. Question is, is there a way, in MATLAB or ...
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2answers
255 views

Interpolated FIR filter group delay

I'm trying to design a digital low pass filter with a narrow transition band. My sampling rate is 25 kHz, the cut off frequency is 60 Hz & the transition band width is 4 Hz. I'm looking for about ...
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1answer
214 views

State-Space Representation of Forward and Backward Filters

In [1], the author shows an efficient way of implementing the forward and backward filter using matrices. One can also implement this using filtfilt command in ...
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1answer
210 views

Arbitrary Phase FIR design using FFT

I want to design a digital FIR filter to cancel the phase of an analog Butterworth filter (i.e. the phase is smooth) i.e. the filter has unity gain with just an inverted phase component. The ...
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1answer
558 views

Gaussian window and standard deviation

I am trying to figure out how to use the matlab gausswin function which constructs a Gaussian window for $N$ samples with a given standard deviation $\sigma$. The function is defined by ...
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1answer
1k views

Get the frequency response curve from FIR filter coefficients + sampling rate

What's the fastest way (if possible in the browser thanks to an online tool, or if not possible easily, with Python), to get the frequency response curve (x-axis: Hz, y-axis: dB), when giving just: ...
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211 views

Relationship between interpolation accuracy, impulse response and frequency response

Global interpolation or sinc interpolation is an ideal filter since its frequency response is a rect function. The impulse response of this filter is the sinc function (same as the coefficients of the ...
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1answer
63 views

Help generating coefficients for basic FIR LPF

I'm trying to generate coefficients for a FIR low pass filter to be used in an FPGA. I'm using python (scipy.signal) to attempt to do this, but am having trouble getting coefficients in a usable form....
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384 views

Which FIR filter window to choose?

I need to design a high pass FIR filter based on parameters given. However I'm stuck at which window i should select. How do I calculate the parameter M? The guide I referred myself to was behind ...
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1answer
1k views

Designing high-pass filters using impulse invariance

One of the main disadvantages of realizing digital filters using impulse invariance is aliasing. According to the Nyquist sampling criterion, in order for the frequency response of the digital filter ...
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2answers
2k views

How to implement a filter associated to a specific wavelet

I am working on ECG signals, to eventually extract features in order to detect an arrhythmia and classify it. I am using Discrete Wavelet Transform with biorthogonal wavelet bior6.8 During my research,...
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1answer
127 views

Instantaneous velocity and displacement from acceleration signal using a proper filtering method

first I need to mention I'm new to signal processing. here is the situation: I have an acceleration time-series derived from an accelerometer I wanted to imply a filtering method like high pass ...
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51 views

filter design steps and process [duplicate]

I started to learn MATLAB and reading paper.i have faced difficulty where to start, how to start in the field of biomedical signal filtering (fNIR)?
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113 views

Design a filter which passes all frequencies except $\omega=\pm\frac{\pi}{2}$ and plot its pole-zero diagram

Also draw its normalized frequency response. What is the ROC? This has to be done in z-plane so there must be two poles at $+i$ and $-i$ since they cannot be included in region of convergence. Is my ...
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329 views

MATLAB: How to filter a signal using Thiran Fractional Delay Filter

I have generated a Thrian fractional delay filter using (thiran function) in MATLAB h=thiran(0.3,1) where 0.3 is the time delay and 1 is the sample time. The ...
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149 views

Binomial Approximation of Gaussian Distribution

It is said that we may use the binomial coefficients ( a layer from Pascal's triangle) to approximate the 1-D Gaussian kernel with certain $\sigma$, where $\frac{n}{4} = \sigma$ and $n$ is the index ...
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2answers
384 views

Alternative to Extended Kalman Filter when prediction function is not differentiable

I am looking at a tracking problem. It can be modelled similarly to the Extended Kalman Filter: $$ \begin{array}{rcl} \mathbf{x}_k &=& \mathbf{f}(\mathbf{x}_{k-1}, \mathbf{u}_k) + \mathbf{w}...
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448 views

Help with audio EQ cookbook BPF filters and Q

I am fairly new DSP, and am using maths that I have not used in 20-30 years. I have been working with Cookbook formulae for audio EQ biquad filter coefficients by Robert Bristow-Johnson and am having ...
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1answer
132 views

Can I have some feedback on this research paper?

I have submitted this paper "Effect of Transducer Positioning in Active Noise Control" to arXiv. I would like to get some feedback on the methodology of the same. Inputs of any sort are welcome. Can ...
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2answers
79 views

Digital filter simulating hydroacoustic signal distortion

Preambule: I'm designing a sound model for my small submarine game. Model is running on the server, and I want to present the client with a mono-channel wav-stream from his hydrophone (20kHz ...
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1answer
88 views

Is this sampling frequency right?

I designed a Butterworth second order bandstop filter on Matlab with the following parameters: Notch frequency: 150 Hz (the frequency I want to remove) Bandwidth = 8 Hz, that is Fc1=146 Hz Fc2=154 ...
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1answer
119 views

Wavelets and bank filters

The wavelet transform has a problem as it gives poor time resolution for low frequencies and poor frequency resolution for high frequencies according to uncertainty conditions. This appears well ...
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1answer
79 views

Measure the length of curves via a smartphone's accelerometer

Is it possible to measure the length of curves by moving a smartphone along them and processing the accelerometer's data? For example, measure the circumference of a circle of radius $8 \,\rm{cm}$. ...
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2answers
2k views

What is the difference between the sampling frequency of signal and sampling frequency of filter

I believe that there is no connection between the sampling frequency used for converting an analogue filter to digital filter and the one used to sample a signal that the filter will be used on. But I ...
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156 views

About how to increase the FIR filter sampling frequency in FPGA? And what is the tradeoff of increasing the sampling frequency?

I am trying to implement a FIR filter on FPGA and trying to have a solid understanding of the FIR filter tap delay and sampling frequency. Does the “one tap” delay equal to “1/Fs (sampling frequency)”...
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2answers
100 views

Can I combine an IIR (an EWMA) with a maximum?

I'd like to have a exponentially weighted moving average (EWMA) which is raised to the value of the input signal whenever this is higher than the filter output. This taking of the maximum shall take ...
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4answers
82 views

Can I use IIR or FIR to get a sliding mean?

My output signal shall be computed by (meta code): o = 0 # or some arbitrary initial value for i in input: o = (o * 99 + i) / 100 print o I call this a "...
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1answer
316 views

Design Lowpass Filter With -7.5 dB/Octave Rolloff

I am working on a project that needs a lowpass filter with a -7.5 dB/Octave rolloff. This is somewhere between the rolloff of a one-pole and two-pole filter, so I wanted to ask what some standard ...
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1answer
289 views

Butterworth low pass filter zeros location after bilinear transformation explanation

I am studying in a text book the transformation of a continuous time Butterworth low pass filter into a discrete time filter by means of bilinear transformation: $$ s = \frac{2}{T_d}*\frac{1-z^{-1}...
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44 views

Phase response approaches towards the zeros

Phase response is the relationship between the phase of a sinusoidal input and the output signal passing through any device that accepts input and produces an output signal, such as filter.https://en....
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1answer
1k views

Transition bands and passband gain in digital filter design

In an ideal design, a digital filter has a target gain in the passband and a zero gain (−∞ dB) in the stopband. In a real implementation, a finite transition region between the passband and the ...
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1answer
511 views

“fred harris rule of thumb”:

I would like to cite "fred harris rule of thumb" for estimating filter order. Is there a book or paper where I can find this rule of thumb? Thanks a bunch.
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68 views

Optimization‏ FIR filter

I have a doubt about this : Iterative methods for optimization‏ in FIR filter (on the one hand traditional like window,frequency sampling ,WLS,Remez Exchange...,on the other hand evolutionary methods ...
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1answer
272 views

Least Squares Linear Phase FIR Filter Design

In explication ''the geometric interpretation of least squares'' Typically, the number of frequency constraints is much greater than the number of design variables (filter coefficients). In these ...
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417 views

Get difference equation of a filter from MATLAB transfer function coefficients

I need to get the difference equation of a specific elliptic filter. I calculated the transfer function coefficients in MATLAB with: ...
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3answers
110 views

different moving average filters differences

Suppose we want to use a moving average filter (3-point moving average) for $X[n]$ (where $Y[n]$ is output). What are the differences among $Y[n]=\frac13X[n-1]+\frac13X[n]+\frac13X[n+1]$, $Y[n]=\...
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1answer
122 views

Optimal Chebyshev FIR filters

I have many information i want to be clear very well . The defining characteristic of FIR filters optimal in the Chebyshev sense is that they minimize the maximum frequency-response error-magnitude ...
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1answer
182 views

Design single pass band FIR filter

I'm new in DSP. I want to design single pass band FIR filter using LS method. I have this information : one pass band $[-0.1\pi , 0.3\pi]$ two stop bands $[-\pi , -0.18\pi]$, $[0.38\pi, \pi]$ ...
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27 views

Direct form I and Direct form II

I was studying about realization structures of digital filters. Is it mandatory to have the order of numerator must be less than that of denominator of transfer function for realization of filter ...
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2answers
895 views

How to Design a Pre-emphasis filter knowing the gain, a zero and a pole?

I am simulating an FM radio signal in order to use it as a waveform in passive radar; for this purpose I'm following an article: Analysis and Emulation of FM Radio Signals for Passive Radar In a ...
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2answers
5k views

Determining the Filter Coefficients of an FIR Filter

I need to find the filter coefficients of an FIR filter that will block sinusoids of frequency $200\ \rm Hz$ if the sinusoid is sampled at $1.2\ \rm kHz$. I feel like this is a fairly simple problem,...
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1answer
3k views

Pre-emphasis filter for speech recognition

I'm trying to design a: $$H(z)=1 - 0.95z$$ FIR filter, for speech signal. I am using this arm_fir_example_f32.c code shown below. And I need to change the filter ...
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1answer
178 views

Biquad Treble Shelf filter gain being weird

Trying to compute Biquad Coefficients for use in a codec chip TLV320AIC3100. Bass Shelf(boost and attenuation) work as expected. Treble Shelf attenuation works as expected but Treble Shelf boost is ...
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3answers
176 views

Why make the phase of an FIR filter linear?

I am new to DSP and filter design. It is easy to design an FIR filter with linear phase by making the coefficient sequence symmetric. However, why make the phase linear?
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44 views

Discrete Hilbert transform enhancements?

Consider the Discrete Hilbert Transform, which takes a sequence $u[n]$ defined on the interval $-M\leq n\leq M$ and returns the discrete convolution $$\tilde u[n]=\sum_{i=-M}^Mu[i]h[n-i]$$ where the ...
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1answer
112 views

Filter bank for complex spectrum

I'm using a complex-valued baseband signal as my input for subband adaptive filtering. Therefore i have a complex input spectrum. My problem is now, how to split my complex spectrum into $N$ equally ...
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1answer
757 views

Implementation of the filter function (Matlab) C/C++

I am trying to apply some filtering in C/C++ code, I have designed an algorithm using Matlab and it works well, so now I am moving it to native code. I am ...
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1answer
174 views

Best way to process this signal

I am novice in signal processing, and i have to aplogise for my english level. The problem is the next: I work for foundries, in this sector the cast parts are manufactured pouring liquid metal in ...
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2answers
111 views

Stable digital filter with leading zeroes

I'm looking construct a stable pole-only filter where the feedback coefficients start with a block of zeroes, i.e. \begin{align} a_0 &= 1\\ a_i &= 0, \textrm{ for}\ 1 \le i \lt k\\ a_i &\...
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Design of a filter with given bandwidth and sidelobe level using Parks–McClellan algorithm

I want to design a filter (beamformer) with a given bandwidth (beamwidth) and sidelobe level using Parks-McClellan algorithm. I use "firpm" function of MATLAB. however, I cannot reach a solution for ...