A high-pass filter is a device that passes high frequencies and attenuates frequencies lower than its cutoff frequency.

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How to produce a high-pass filter from a low-pass one?

I already have a low-pass filter and want to remove the DC offset of a signal with a high-pass one. I guess you can subtract a low-pass filtered signal from the original signal and the result is a ...
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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 ...
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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 ...
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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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32 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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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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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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301 views

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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294 views

how to design a high pass filter to remove dc offset from signal

I want to design a high pass filter (f0*S/1+f0*S) in order to remove the dc offset from a signal ? (i.e. how to choose the frequency f0). Thanks, Hacene Ps : the filter is for matlab implementation, ...
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digital filter and epoch length

A reviewer has asked me to re-filter my data to remove baseline drift. Each sweep is 170ms sampled at 1000Hz and the reviewer wants it high-pass filtered at 0.5Hz. The original bandpass settings on ...
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Signal leveling using scipy

Apologies if I'm using incorrect terms, and if this question's already been answered here. I have a data set which consists of a high DC signal modulated by AC signal (taken from custom-built ...
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Which kernel produces sharper image

kernel A = [ 0 -1 0 -1 4 -1 0 -1 0 ] and B = [-1 0 -1 0 4 0 -1 0 -1 ] i have found the frequency spectrums with ...
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filtering fft spectrum further?

I am working on bearing faults.I did the high pass filter and then calculated the envelope of the signal in the time domain. I then found its fourier. The fft spectrum is still not clear. My ...
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2answers
551 views

Filter size vs. FFT size and Overlap add

First of all I would like to say that : I'm new to DSP and in a "learning curve" hence the "basicness" of my questions. I've read as many posts/articles as possible on the internet but still need ...
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1answer
527 views

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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1answer
106 views

Highpass filter applied to noise

Suppose the input signal is represented as $$y=x+w$$ where $x$ is the signal to be estimated and $w$ is AWGN. I design a high pass filter $H$. What does $$H^{T}Hw$$ represent? Will it be just AWGN but ...
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1answer
766 views

Mathematical Proof of Complementary Filter´╝č

Having found some unofficial sources on Complementary Filter (Thousand Thoughts Sensor Fusion and The Balance Filter by Shane Colton), I wish to work out its rigorous mathematical proof. The ...
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Negative values from High Pass filtering

I come from Fluid Mechanics domain so pardon me for asking a naive and fundamental question. I am trying to perform high pass filtering on a set of positive real numbers (~Energy) using FFT. ...
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Anybody with experience with online double integration of acceleration?

I've found good literature for offline proccesses, and I've gotten good results. However, when it comes to online applications, I've found nothing good. Applying any filter without a linear phase ...
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272 views

How to determine the parameter of a Complementary Filter?

I know that the Complementary Filter has the functions of both LPF and HPF. But I think my understanding on the principal behind it is still unclear. I am quite new on digital signal processing, and ...
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High Pass filter

I am new to signal processing and im trying my best to figure out how to build a high pass filter then later on implement it. (in c#) Edit: I rewrote the question with math notation, if someting is ...
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444 views

How do decide which order my butterworth filter should have?

I have a signal that was recorded with around 300 samples in a second. Now I want to run a low pass and a high pass butterworth filter over it. The frequency for the high pass filter is around 0.05 Hz ...
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Why is Prewitt filter High Pass

Prewitt filters are popular filters in image processing for edge detection http://en.wikipedia.org/wiki/Prewitt_operator Can anyone give a proof on why Perwitt and other edge detecting filters are ...
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LPF and HPF Confusion - Rectangular and Circular Cut-Offs

Interpreting some homework, I'm a little confused on what it's asking for. I'm asked to filter in the frequency domain (easy enough, just a fft2 and ifft2 when I'm done) a 256x256 8bit grayscale tiff ...
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Is it correct to subtract a low-pass filtered signal from the original signal and use the result as a “high-pass”?

I am having a hard time trying to find documentation to implement band-pass or high-pass filter with python/scipy/numpy. I can easily create and apply a low-pass filter, though, so I ask: Would it ...
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281 views

Filtering of streaming audio

Given something like 103 data points ($N=103$), a DFT will give back 103 frequency values. Then to do something like filtering the high frequencies involves setting the high frequency values from the ...
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complementary IIR filters

I would like a pair of complementary IIR filters (lowpass/highpass). By complementary, I mean, when the output from the two filters is summed, the original signal is recovered. I thought I could build ...
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Analyzing movement of fringes

I have taken a series of images of a fringe pattern at regular time intervals. This fringes are generated by shining a laser beam onto the CCD camera. The laser goes through a lot of optics, which is ...
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Normalizing Negative filter coefficients for Digital filter design

I am designing a High pass Digital filter. I calculated the filter coefficients using fdatool and got some negative filter values. Now, I need to convert them into values from 0 to 255. In case of ...
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What is the physical interpretation of Lowpass/Highpass filtering?

In Image/Signal processing context we have seen/we know that if there are say 4 samples and if we take an average of those 4 samples, then we say that the result sample is a low pass filtered output ...