Questions tagged [highpass-filter]
A high-pass filter is a device that passes high frequencies and attenuates frequencies lower than its cutoff frequency.
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Restoration problem with numpy fft function and self-made high-pass filter
Hi, I am using numpy.fft functions to do CV assignments in univ.
But while implementing the high-pass and low-pass filter, I found something wrong during the process.
The difference should converge ...
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0answers
22 views
Determine filter type using recurrence relation
Given the recurrence relation:
$y[n] = x[n] + 0.5y[n-1]$
I want to determine the filter type (i.e. LPF, HPF etc.)
I try to use Z transform, and get that the the transfer function is
$H(z) = \frac{2z}{...
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2answers
247 views
Is the Sobel filter a high pass filter, and if not, what is the difference between them?
I am an artist with an interest in signal processing. I realize that maybe this question very basic, but the web banner on the frontpage says "anyone can ask", so I assume that means beginners too.
...
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1answer
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Why do cutoff frequencies of a high-pass digital filter differ from the ones i used to transform it from a low-pass analog filter in MATLAB?
I need to transform an elliptic analog low-pass filter to a digital high-pass filter but i'm having a problem because the resulting filter has lower cutoff frequencies than the ones i set. Here is the ...
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1answer
61 views
Are there DC removal techniques that do not introduce a filtering transient?
I have an application in which I need to remove DC components from a sampled signal in real time (basically the same constraints of ECG, but it has nothing to do with the brain). My measured signal in ...
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3answers
234 views
How to Classify Image Filter as Low Pass Filter (LPF) or High Pass Filter (HPF)?
I am currently reading on the topics of image filtering and convolution kernels. While the process of convolution is clear to me, I do not understand, how one arrives at the statement, that a certain ...
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1answer
110 views
Background Noise Reduction in Audio signal
I using high pass filter for reduction or removal of noise of audio signal but still some noise is there in signal.i have MIC,Head Set,Bluetooth and phone are connected to controller,while talking on ...
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1answer
76 views
How to understand the relationship between the filter time constant and the half-power cutoff frequency
I learned that the time constant can be computed as $\frac{1}{2 \pi f_0}$, where $f_0$ is the half-power cutoff frequency of a high-pass filter.
However, I was wondering how the time constant and the ...
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1answer
166 views
Poles and zeros map
Given the following map of poles and zeros for some $H^L(s)$:
How can I understand from the map that the given Transfer function is LPF?
Hence the poles are located at the hight frequencies it should ...
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2answers
71 views
High/Low Pass Filters from Zero
I everyone,
I'm a computer scientist but not from the signal processing community. I want to implement a real time digital low pass filter (to begin with) for a sound processing application. I've ...
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How to combine filters' effects?
My question is about the use of many filters on a sound signal.
I found the following transfer functions for the high cut, the low cut and the pass band filter :
H = K / (1 - x^2 + j.x/Q)
H = K / (1 -...
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Low/High cut filter : how does it work?
I have a question about the low-cut and high-cut filter on an equalizer. Let's say, for example, that I'm using a 15 band equalizer with the following central frequencies: 25, 40, 63, 100, 160, 250, ...
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2answers
81 views
Are there any quick way to tell if a kernel is a high-pass filter?
Im new in this image processing field so please be gentle with terminology, i have a kernel of 3x3 and i want some way in order to test if its a high pass filter or not
Thanks in advance
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2answers
529 views
How to Classify a Kernel as Low Pass Filter (LPF) or High Pass Filter (HPF)? How to Transform an LPF Kernel into HPF Kernel?
The filter impulse response is [1/9 1/9 1/9;1/9 1/9 1/9;1/9 1/9 1/9].
how do i determine whether it is an Low pass filter or a high pass filter. If this is a low pass filter how do i convert it to a ...
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1answer
100 views
temporal high-pass filtering to approximate phase derivative
I am currently following the algorithm as based on a previously published research article "A Motion Detection Algorithm Using Local Phase Information" by Lazar et al. The basic overview of the ...
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193 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
723 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
499 views
How to apply Butterworth High Pass Filter [closed]
I have a problem with applying Butterworth High Pass Filter to my data. I would like to print filter for Bx and By matrix. As ...
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2answers
662 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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1answer
40 views
Modulation and filtering
When I modulate a signal $x(t)$ with $\cos(2 \pi f t)$ and the modulated signal passes through a HPF, what output do i get in the frequency domain?
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1answer
498 views
Real-time FIR filtering on time domain
My previous question wasn't clear. So I thought it'll be good idea to repost with more details.
I've designed a 100th order windowed highpass FIR filter with 3Hz cutoff frequency for my ADC datas ...
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1answer
178 views
Butterworth high pass filter
My signal's base line is around 1. When I apply Butterworth high pass filter with cut off frequency Fc = 2Hz signal's base line drops to 0. My data are from the accelerometer. Is this behavior normal ?...
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2answers
291 views
Why did a digital HPF increase the gain of high-frequency signal?
Background: I was trying to remove the DC component of a load cell signal using a high-pass filter. I don't care about that anymore. I'm curious why a digital filter and an analog filter behave ...
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3answers
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Filter design - Rules of thumb regarding ratio of sampling and stop/pass frequency
The issue: I have a signal in the time domain sampled at 51.2KHz. I want to apply a highpass filter with a pass frequency of 20 Hz.
The problem: Using Matlab to do that, the design of the filter ...
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2answers
144 views
How to get output from High Pass filter on this signal?
I'm trying to solve this exercise:
Consider a High-Pass filter with a cutoff frequency of $W=2\pi$
Calculate the output signal if the input signal is $x(t)=\displaystyle \frac{\sin(4\pi t)}{\...
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1answer
430 views
Forward Backward filter Scipy - $\tt signal.filtfilt$ changes the amplitude when $\tt signal.butter$ is used with $\tt btype='high'$
In the plot below the blue wave is the original signal. The orange wave is after the low pass filter. The green wave is after the high pass filter.
I have a noisy ECG signal stored in the ...
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2answers
935 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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2answers
290 views
Determine filter type (HPF or LPF) by its coefficients
I want to determine optimal initial states for a FIR/IIR filter to get rid of oscillations and shifts at the initial interval.
I've found that these initial states depend on filter type in the ...
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1answer
7k 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
5k views
Differences between low-pass, band-pass, notch filters
I'm studying image processing and I know that there are different filters you can apply. I don't understand the difference between the low-pass/bandpass/notch filter (or high-pass/band-reject/notch). ...
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1answer
287 views
Why is the lowpass-filter coming right after the local oscillator when mixing an RF?
In the book, instead of having a band- or lowpass-filter before mixing, it's coming right after mixing, which makes sense, considering there's gonna be a high-frequency component, which has to be ...
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2answers
451 views
What is the name of these simple filter algorithms?
I found some snippets of code on the internet that are really simple signal filters. Unfortunately there wasn't much info to back it up. Using Google I've found similar code, but none of it backed up ...
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1answer
69 views
How could I remove the central red line
How can I remove the central line; there is someone told me use high-pass filter, is that right? how to use it in matlab
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3answers
277 views
Problems designing high pass FIR filter with $f_\textrm{cutoff} \ll f_\textrm{s}$
Is there any inherant problems with high-passing a signal with a very low cutoff frequency compared to the sampling rate?
I'm not sure what I am missing as I cant find any info on it.
Examples ...
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1answer
3k views
How to convert a low-pass Gaussian filter to a high pass filter
I have the following code for a applying a Gaussian filter to an image. From what I understand this is a low pass filter. Now I have to convert this into a high-pass filter, and from what we were told ...
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How do I design a speed-efficient high-pass filter to replace slow polynomial filter? [closed]
I have the recorded membrane potential of a neuron, and I want to get a more even baseline by removing certain slow changes from the signal (see figure). The best way to achieve this thus far has been ...
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Two way Audio crossover MATLAB code using Bessel
Could MATLAB's besself function be used in designing an Audio crossover (Tweeter and Woofer) with highpass and lowpass filters?
Most likely the same with this ...
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1answer
105 views
Why is the frequency response different based on the amplitude of the impulse I feed into the filter?
I am working on a 2-pole IIR high-pass filter. The filter is fixed point and it is causing me some issues. I believe I'm just misunderstanding something. I am implementing everything in Octave for ...
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1answer
4k views
How can I construct a Band-pass filter from a low and a high-pass filter?
Suppose, I need to construct a Band-pass filter in OpenCV. But, I know, there are no functions in OpenCV for Band-pass filters.
Now, what I need to do is to have a low-pass filter and a high-pass ...
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1answer
68 views
Difference equation with complex zero
Let's assume I have the following transfer function:
$$
H(z)=\frac{z-\left(\frac{1}{\sqrt{2}}+i \cdot \frac{1}{\sqrt{2}}\right)}{z}
$$
It looks like a first order highpass-filter with a complex zero ...
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1answer
140 views
how to design LPH and HPF from APF
I came across a concept that says we can design LPH and HPF from APF when the transfer function of the two APFs given as
$$\begin{align}A_0(z)&=1\\
A_1(z)&=\frac{-a+z^{-1}}{1-az^{-1}}\\\\
H_{...
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1answer
106 views
Should I use a high pass filter or low pass filter to enhance the features for image splicing detection?
I'm recently learning image splicing detection. I've already known image splicing can bring some abrupt changes to an image,which generate the sharp edges.And sharp edges correspond to high frequency. ...
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2answers
1k views
High-pass filtering pre-processing before computing audio features
I want to compute acoustic features on a set of audio files. These features can be classical audio features as spectral flux, but also acoustic indices as proposed in the seewave R package ).
I need,...
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1answer
2k views
Butterworth High Pass Filter Amplitude Response
I have learned the Butterworth filter, normally it is used for low pass design. And the amplitude response is:
$$|H(jw)|=\frac{1}{\sqrt{1+(\frac{w}{w_{c}})^{2n}}}$$
mentioned in this Butterworth ...
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1answer
114 views
is any filter whose impulse response has a discontinuity in the first derivative fundamentally high-pass?
a triangular (bartlett) window has a kink (discontinuity in first derivative). thinking in the continuous (not discrete) case, my intuition is that the fourier transform of any window with a kink ...
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1answer
120 views
What is the name of the following 1st order high-pass IIR filter?
What is the name/family behind the following high-pass IIR filter:
$
T = 1/f_s \\
f_c = 5 \\
c_1 = \displaystyle \frac{1}{1 + \tan(\pi f_cT)}\\
c_2 = \displaystyle \frac{1 - \tan(\pi f_cT)}{1 + \tan(\...
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4answers
2k views
filter coefficients to know high pass and low pass filter
Looked on few questions already there in dsp.stackexchange and couldn't get the direct answer. Basically I have a kernel of a gaussian separable filter.
...
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1answer
194 views
Transfer function, amplitude response and difference equation for a filter
I've found a paper with a filter described in terms of transfer function, amplitude response and difference equation:
transfer function of the second-order low-pass filter:
$$
H(z) = \frac{(1-z^{-6})...
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2answers
561 views
Applying a high-pass filter on constant signal
I recently implemented a Butterworth high-pass filter (2nd order). Everything seems to work fine, except that I have a question when applying such a filter to a constant signal. As there are no high-...
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0answers
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How many different filters are needed for in an iterated filter bank?
I'm trying to implement an iterated filter bank as described in the Subband coding chapter of the Really Friendly Guide to Wavelets. However, the text seems to suggest that
The advantage of this ...
