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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444 views

FIR Filter - Low Pass Filter coefficients to High Pass filter coefficients

I need to convert this 12 Tap Low Pass Filter to a High Pass Filter. The coefficients of the Low Pass Filter are as follows: ...
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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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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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176 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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Filter order and cut off frequency

How can I know exactly what frequencies are not influenced by the filter? I mean, I have a signal in the range of frequencies $5-100 Hz$ and I apply a high-pass, $4^{th}$ order Butterworth filter ...
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1answer
811 views

How to find roll-off from its transfer function equation?

I want to find roll-off (unit dB/decade) of highpass filter $H(z) = 1 - a \cdot z^{-1}$. I derived magnitude response to be $1+a^2 - 2a\cdot \cos(\omega)$ To find out roll-off factor from above ...
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278 views

How can you intutively figure what the impulse response will behave like?

I was trying to understand convolution from this book and came across this figure: Here, the input signal is a combination of a sine wave and a ramp. In fig a, the input signal is convolved with a ...
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Design of 10th order high pass filter using 2nd order biquads with Matlab and further substitution on to TI AIC3204

I am involved in designing a 10th order high pass filter with cutoff frequency 300Hz. My hardware AIC3204 has a 5 biquads of direct form I, 24bit coefficient so I have chosen the FDA (filter design ...
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81 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 ...
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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 ...
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81 views

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 ...
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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 ...
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1answer
343 views

Remove audio signal component under certain frequency in python

I want to remove all signal components under 10KHz in one audio file. Below is my code ...
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41 views

Problem with implementing DC offset for streaming data

I am new to the DSP world. I'm trying to run a raw input signal through a LPF, remove any DC offset, amplify the signal, and then decode the signal. The problem with my code seems to be the ...
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33 views

Adjusting coefficients of a LP and HP filter for a new sampling rate

I am pretty new to DSP and try to undertand some concepts and the relations between them. I currently learning about the Pan-Tompkins algorithm and trying to recreate it in Matlab (Pan–Tompkins ...
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1answer
64 views

Correct signal analysis flow (Wind Turbine vibration)?

I have vibration data from WT (gearbox) sampled at 25.6 kHz. From a previous post I received a lot of good recommendation. What I am trying to do: Find early stage bearing faults by using an ...
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76 views

FFT response for noisy signal, averaging the response and

I try to analyze a system's state with acceleration sensors by measuring the frequencies and amplitudes. Since a cheap sensor is used, I have a noisy signal in the beginning (up to 40Hz - see below). ...
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1answer
77 views

Attenuate the low frequencies in a speech wave

I am designing an FIR filter to attenuate the frequencies below 300Hz. I designed the filter using the ...
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1answer
2k views

Poles and zeros map, High pass filter

Given the following poles and zeros map I have to identify qualitatively, which filter type is represented (Low-Pass, High-Pass, ...). In the solution it says, that this is a high pass filter. ...
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90 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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1answer
113 views

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
866 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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182 views

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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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
496 views

How would I go about designing a difference equation for a given type of filter?

I have experience using design tools such as Xilinx's CoreGen and MatLab's DSP tool kit, but I have not really had much experience designing filters from the ground up. Reinventing the filter as it ...
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1answer
202 views

How to predict the cramped frequency of a digital filter based on an analogue frequency?

I have a second order analogue high pass transfer function (unity gain at infinity). It's magnitude response hits the -20 decibel line at a frequency of 5706 Hz (the corner frequency is 18000 and ...
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1answer
156 views

Correction of signal after High-pass RC-filter

I have one question about digital correction of signal after RC filter which is high-pass. Let me explain detail. I have one simple signal conditioner. It has RC filter on the signal input with cut-...
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1answer
954 views

Apply FIR filters to Extract Stego from WAV data

I appreciate anyone that takes a moment to help me with this problem. I've been banging my head against the keyboard for a while, searching forums and DSP tutorials and I can't figure this problem out....
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282 views

Why Matlab fdatool designed butterworth filter and butter command's co-efficients are different

I met an great confusion. Using below command I have got co-efficents for a 300Hx cut-off high pass filter of order two. [z p k] = butter(2,(300/44100),'high') [sos,g] = zp2sos(z,p,k) Now this ...
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377 views

High Pass Filter, effect of applying it on this image.

I am having question about the HPF. In particular, it is having a high pass guassian filter which is applied to the original image below. High pass filter should only detect edge (lots of change in ...
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Audio signal processing

I am trying to code audio signal processing software in java. Purpose: It will use audio signal processing library to filter out noise from the raw PCM based input (.wav) of heartbeat recording. ...
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24 views

New magnitude frequency after apply highpass butterworth filter

I want to use high pass filter to filter frequency less than 100Hz. I use this code in python. ...
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1answer
717 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
2k views

How do I identify CUTOFF frequency from my audio signal? [closed]

I was able to recorded an audio signal through the MIC and i applied FFT and Hanning window function to it. Now I want to know how do I identify CUTOFF frequency from it to apply the High Pass Filter. ...

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