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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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25Hz low-pass FIR filter for 96kHz high-quality audio

I am evaluating how to implement 25Hz low-pass / 25Hz high-pass filter with flat phase response (i.e. FIR). Apparently straightforward FIR filter would require insane number of taps (>8192) which ...
BarsMonster's user avatar
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3 answers
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Recover high pass filtered square wave

I'm designing UHF RFID receiver. My receiver has high pass filter and I would like to recover original square wave and then use matched filter. My high pass filter is in hardware and it is difficult ...
rf-engineer's user avatar
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Quasi-static-detector operation principle

Im currently working on a project to get navigation information of a robot from Data-Fusion through different IMUs. First step is to make a calibration and I picked a method where I need to detect ...
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Does the high-pass filter cause the accelerometer to miscalculate displacement?

I have an accelerometer and I've written a program for it in the ESP32. The program uses a 750sps ADC sampling rate and an accurate 100Hz interrupt for calculations. P.S. The high-pass filter is at 0....
leo_0916's user avatar
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Unstable high-pass filter on mouse-generated signal

I am making a Desktop application using PyQT as the app is a Digital Filter You can add zeros and poles to a unit circle and apply the filter to the data the data can be of two types 1- saved data on ...
Mohamed Hazem's user avatar
1 vote
2 answers
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Unstable high-pass filter on mouse-generated signal using Python

I am practicing some DSP techniques along with desktop application development using Python and PyQt. In my filter design application, I am able to create a filter by placing zeros and poles on a unit ...
Kafka's user avatar
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4 answers
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3-point highpass filter

I came across an interesting question from Strang & Nguyen$^\color{magenta}{\dagger}$ where it asks to design a $3$-point (or 4-point) high-pass filter with better performance than the $2$-point ...
Sami Al-Dalahmah's user avatar
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Calculating the settling time of lowpass and bandpass SOS filters constructured using SciPy

I have constructed a high pass filter using scipy: ...
BeginnersMindTruly's user avatar
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1 answer
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Numeric Derivative Frequency Response

It seems quite common to use np.diff() for removing DC components of signals when plotting spectrograms. I noticed some unexpected behaviour during analyis which ...
Daniel Wait's user avatar
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27 views

Issues with ML Pattern Recognition After Bandpass Filtering

We've been working on a machine learning project for pattern recognition, using time-domain features such as kurtosis, mean, standard deviation, variance, skewness, and peak-to-peak values. Background:...
Tarek's user avatar
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1 answer
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High pass filter with low cutoff frequency

I'm trying to design the highpass filter in Python for my accelerometer data in order to integrate them. I need to preserve low frequencies. For example, data with a sampling frequency of 2 kHz need ...
Martin E.'s user avatar
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Demonstrating linear filters on daily weather data

I have daily temperature data from some place on Earth. Apparently, the sampling frequency f_s = 1/day. I would like to use these data to demonstrate (visually) the use of low-pass, high-pass, and ...
Michael's user avatar
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Poor Attenuation With High Pass Filter

I am having issues with my implementation of a FIR high pass filter. The low pass filter has an acceptable level of attenuation in the stopband, but the high pass filter has poor attenuation in the ...
expr_champ2's user avatar
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What highpass filter is implemented in Audacity?

When I selected highpass filter effect in Audacity (an open-source audio editor), it lets me choose the cutoff frequency and the roll-off but it doesn't specify which filter type is used (IIR ...
Triceratops's user avatar
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2 answers
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Get rid of DC offset by subtracting mean, but still have impulse at f = 0 Hz

I understand that there are two ways to get rid of DC offset: (1) subtracting mean of original signal in time-domain, (2) using high-pass filter. I'm trying both approaches on my data (using Matlab) ...
trrees's user avatar
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digital Butterworth high pass filter

I am trying to high-pass filter a signal using a Butterworth filter, but I am getting the following results : As in the picture, there is no signal decay. python code: ...
RACHID BEN ABDELMALEK's user avatar
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Is f/fL a high pass filter where fL is a low-pass version of f?

Let there be a signal f and its low pass filtered signal be fL. Then what can we say about the spectrum of f/fL ? To be specific I am obtaining fL simply using gaussian blurring in the spatial domain. ...
Mohit Lamba's user avatar
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3 answers
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FIR-filter output gain

Lately, I've been doing some FIR-filter simulations as a part of a programmatic circuit design course. One task was to use different constants $b_i$ for the multiplying stage of the filter and see how ...
user294957's user avatar
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2 answers
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Which signal corresponds to the high-pass version of the original signal?

I have wandered into the realm of signal processing and am currently focusing on learning more about filtering signals. I am currently trying to understand how to think about and solve a practice ...
KSI's user avatar
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2 answers
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Filter amplifies frequencies at nyquist frequency. What's the purpose of such a filter?

I'm currently facing a filter that amplifies frequencies at the Nyquist frequency. The sampling frequency is $f_s = 10$ Mhz. What's a typical application for such a filter? This is how I generated ...
Julian Sarcher's user avatar
1 vote
2 answers
597 views

Constraints on number of taps in a FIR filter vs. FFT length

I want to implement a FIR highpass filter for acoustic signals. I generate the FIR using Python's SciPy code: ...
Triceratops's user avatar
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1 answer
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How to choose the cut-off frequency for removing the DC components

I'm trying to remove the DC components from a signal in a static situation (there is no movement), so I'm using a high pass filter with a cut-off frequency of 0.1 Hz (since the DC components happen at ...
jon's user avatar
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4 votes
2 answers
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Wider sharpening filter

The kernel of a sharpening filter of size 3x3 may look like $$ \frac{1}{4}\begin{bmatrix} 0 & 1 - \alpha & 0\\ 1 - \alpha & 4\alpha& 1 - \alpha\\ 0 & 1 - \alpha & 0 \end{...
user877329's user avatar
11 votes
5 answers
6k views

Why does the derivative of an audio file act like a high-pass filter?

Code: https://github.com/echometerain/sound-derivative/blob/master/sd.py I wrote a program which would subtract the current audio frame by the former one. Why does this act like a high-pass filter?
Rain's user avatar
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High Pass Filter for Image using C++ and Python

I was assigned to optimize the HPF using C++. Fyi, the original image is 512x512. By getting the .dat file that is produced by using Python script, I applied a 5x5 HPF on it with 2 zero-pad with ...
JunJie Lim's user avatar
1 vote
1 answer
415 views

How to detect and distinguish oscillations in a signal?

I would like to detect oscillations in a signal $s$ and determine the nature of the oscillations, i.e. whether they are high-frequency oscillations or not. Edit : An example of $s$ is given below : ...
Mistapopo's user avatar
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How can the detail coefficients in discrete wavelet transform (DWT) be downsampled?

This question is asked with reference to this paragraph For the high-pass filter, the frequency content lies in the range $\frac{F_s}{4} \rightarrow \frac{F_s}{2}$. There is no content in the range $...
Jk Er's user avatar
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Why is there coherence below the cutoff frequency of two high-pass filtered signals?

I record surface EMG signals from two muscles at 1500 Hz. The following preprocessing steps are performed using basic MATLAB commands. First, I decimate both signals to 500 Hz (Lowpass filtering ...
Tydur's user avatar
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1 answer
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How to apply Butterworth high pass filter in the frequency domain?

I have a time series of measurements which I want to high pass with Butterworth filter. Python scipy package has a built in function for Butterworth filter (signal.butter) and I know how to apply it ...
Judita's user avatar
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1 vote
1 answer
761 views

Implementing basic high pass filter using difference equation

For the following signal, I am trying to remove the gradual positive drift but retain the spikes using a high pass filter. I am aware that I can use implement a high pass filter using difference ...
Quazi Irfan's user avatar
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strange waveform after highness FIR filter

I was trying to apply FIR filter on the ECG signal: a bandstop for 45-55 Hz for noise removal and a highpass filter for moving baseline wander. But after that, the ECG signal show strange waveform at ...
nanarua's user avatar
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1 answer
63 views

analog filter magnitude flatness problem

I have designed an analog filter that includes a high pass filter with a cut-off frequency of 5 Hz and a notch filter with a cut-off frequency of 50 Hz. I want to sample the output signal of the ...
macrobert's user avatar
1 vote
2 answers
493 views

IIR Filter Stability

I have designed an inverse IIR high pass filter by inverting its transfer function B(z)/A(z) to A(z)/B(z). However, the inverse filter has a pole at z=-1. Is this filter considered stable (marginally ...
A7mad Ali's user avatar
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0 answers
83 views

How to enhance thermogram image in grayscale?

I'm trying to do some image processing to improve the image below but I'm having some trouble. I already tried to do histogram equalization followed by laplace sharpening, I tried to implement a ...
Mário Fernandes's user avatar
2 votes
2 answers
623 views

Differences in transforming a sinc FIR filter from lowpass to highpass using spectral inversion and spectral reversal

I have designed a lowpass sinc 1023 tap FIR filter with a Blackman window and this works fine. I understand there are then two ways to transform this lowpass filter to a highpass one. One is spectral ...
MikeDB's user avatar
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1 answer
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Bio-signal discontinuity after FIR filtering

I'm filtering respiration signal. I have a signal of duration equal to 10 minutes, so I decided to divided it into period of 10 s. I filtered each epoch with FIR filter, but I have discontinuities ...
Gloi's user avatar
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2 answers
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Should we use a digital low pass or high pass filter to remove sensor bias?

Consider a continuous signal oversampled at, say $2 \;kHz$, and then system digital low pass filtered to a $100\;Hz$ frequency which is the control loop frequency. It is known that there is some bias ...
kbakshi314's user avatar
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2 answers
4k views

How to implement a high pass filter digitally to remove the dc offset from sensor data

I'm trying to implement a high pass filter on sensor data to remove the dc offset. I'm aware I can subtract the mean of the data but I'm looking for a frequency domain approach. I've used the matlab's ...
tryingengineer's user avatar
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1 answer
4k views

RC high pass filter differential equation

I have the question to derive: $$RC \frac{dy(t)}{dt} + y(t) = RC \frac{dx(t)}{dt}$$ which describes a high pass filter or $CR$ circuit with $x(t)$ the input and $y(t)$ the output. I am really ...
Joesphtimeheist's user avatar
1 vote
0 answers
149 views

High pass biquad cascade transposed direct form II low frequency accuracy

I'm quite new to DSP and I'm trying to implement high pass biquad cascade in transposed direct form II. Currently my implementation has very poor accuracy at cutoff frequencies that are less than 5kHz ...
minimalistic's user avatar
1 vote
1 answer
173 views

Highpass filter design that is better than the moving difference filter

From Nguyen & Strang's Wavelets and Filter Banks: Problem 4 Invent a highpass filter $K$ with three or four taps (coefficients) that is better than the moving difference $H_1$: the goal is $$ | K ...
Aquiles Páez's user avatar
4 votes
1 answer
3k views

Low frequency (1Hz) High pass filter

I am trying to get a useable wave from a pulse oximeter, but there is a pesky DC bias that keeps changing every now and then, so I cannot simply subtract the DC bias from it and get useable results ...
Usman Mehmood's user avatar
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0 answers
265 views

Bandpass filter vs sequential high and lowpass filter in Matlab: weird difference

I am trying to bandpass a neural signal acquired at 20kHz between 0.5 and 100 Hz. I have tried to do it in two ways. The first way is to sequentially highpass and lowpass the signal and the second one ...
Anand Kulkarni's user avatar
7 votes
3 answers
893 views

Is there an adjective describing a filter with kernel that has zero mean?

A linear filter with a kernel that has zero mean could be thought of as a "DC-rejecting" filter. Is there a better or more commonly used adjective for such a filter?
Museful's user avatar
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Why use both a high pass and a low pass filter in a Butterworth implementation for noise reduction?

I am a new to audio processing . I want to develop an application that reduces audio noise using a Butterworth filter. I found some existing code doing this, but I still do not understand the use of ...
Youssef El-kantri's user avatar
3 votes
1 answer
88 views

The magnitude spectrum of a sharpening filter

I'm trying to derive an expression for the magnitude spectrum of the following sharpening filter. $$ g(m,n) = \delta(m,n)+\lambda (\delta(m,n) - h(m,n)) $$ where $\lambda$ is some positive constant ...
GuntherOnFire's user avatar
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1 answer
384 views

Simulate butterworth filter with initial condition of state vector in R

I'm working in R with the packages signal and control (don't know wether these are even the best for my use case). I have a high ...
Chen Huang's user avatar
4 votes
1 answer
3k views

Is the Laplacian Filter an High Pass Filter (HPF)?

Is this kernel name as mean difference kernel or Laplacian filter? Is mean difference just a method?
Sun's user avatar
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1 vote
1 answer
330 views

Downsampling after a highpass filter

Question: The following sentence is not clear to me (especially why down-shift occurs). Could someone explain it please? On the other hand, downsampling the output of the highpass filter down-shifts ...
DSPinfinity's user avatar
0 votes
1 answer
159 views

High pass filter not attenuating signal at start of input

I have implemented digital high pass filter with below specs: Sampling frequency = 5333 Hz Cutoff frequency = 10 Hz Order = 3 We are facing problem like below: As ...
Ankit Chudasama's user avatar