A band-pass filter is a device that passes frequencies within a certain range and rejects (attenuates) frequencies outside that range.

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filtfilt giving unexpected results

I am trying to filter EEG signals using butterworth filter and filtfilt. I have gone through a lot of documentation and these 2 commands seem sufficient for filtering. However, the results are ...
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Filtering method that minimizes ringing in time domain, implementable in Python

I am acquiring data through an oscilloscope, which I am then filtering. I am doing all of this in Python. I need a bandpass filter with stop bands from 0 to .4MHz, and 4MHz and up. My pass band needs ...
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How do I manually plot the frequency response of a bandpass Butterworth filter in MATLAB?

I have code like below that applies a bandpass filter onto a signal. I am quite a noob at DSP and I want to understand what is going on behind the scenes before I proceed. To do this, I want to know ...
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Filtering the EEG signals

I have very limited knowledge of DSP, so I apologize if my question is trivial :) I have an EEG signal from which I need to extract different frequency bands. For example, waves in the the frequency ...
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59 views

Why is beginning of this FIR filtered signal attenuated?

I apply an FIR filter passing the band around 50/1000 and attenuating the other three frequency components 30/1000, 70/1000 and 110/1000. Both filters are generated using the Remez algorithm. The ...
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Sampling bandpass signal with spectral replications

I want to clear my thinking on how to approach problems of the type characterized below. I guess what we want to do is select a sample rate of a sufficient size such that this signal can be fully ...
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Energy in baseband and bandpass signal

Is there any difference in energy content of baseband and bandpass signals? When we see their representation in frequency domain, it looks like a bandpass signal has double the energy content compared ...
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150 views

Bandpass Filter window length: filter “in phase” with sinusoidal input

Say you have a bandpass filter and you place it on 40 discretely sampled points from a sinusoid with a period of 40. Why is the bandpass filter (green curve on the image) only "in phase" with the ...
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360 views

Bandpass butterworth filter frequencies in scipy

I'm designing a bandpass filter in scipy following the cookbook. However, if I decrecrease the filtering frequencies too much I end up with garbage at high order filters. What am I doing wrong? ...
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Separating two sound file frequencies using bandpass filter matlab

can someone please help me? I have a project to implement a superheterodyne transmitter and receiver without using matlab functions that modulate. The first part which I can't seem to get right is the ...
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Using goertzel confuses me

I am having some troubles understanding the algorithm. My algorithm looks like this. how come am i able to compute the DFT coefficient using this algoritm. As far as i know $$ X[k] = ...
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How to reverse the effect of analog RC filters on calibration pulse?

I have a low-voltage amplifier with an analog LPF of ~106 Hz and a HPF of 0.482 Hz (both first-order RC). I can choose to apply a calibration pulse that will shut off the input and send a 500uV, 5Hz ...
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49 views

Is it possible to implement FIR band pass filter using two FIR band stop filters?

I am trying to filter a signal using a given FIR band stop filter. I have to implement a band pass filter. Assuming I want to get the signal between normalized cutoff frequencies [0.2,0.3] - can I ...
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113 views

Bandpass filter on noisy sinusoid that predicts turning points

Is there an application where it is required to predict turning-points of a signal that is like a sinusoid with constant frequency, variable amplitude and some noise (Gaussian additive noise)? The ...
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Bandpass Filter Implementation in C

I've been googling for a while and came across the audio cookbook and Bjorn's blog explaining it further Link Here. Background info: I've modified the rtl-sdr open source code to tune to a VOR ...
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69 views

What are filter banks

What are filter banks and what's their application? What's the meaning of $H(z)$ in descriptions of filter banks?
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How to convert a filtered time-domain signal into frequency one? [closed]

I have a signal in matlab like this: I have designed a band-pass filter in 16-32 MHz range: and applied the filter to the signal, the result is like this : My Question: what is the ...
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92 views

Out of memory problem with filter design tool in Matlab [closed]

I have a set of data in excel like this: column A is time in ns and column B is the electric field strength. now I want to convert the time-domain signal from these data to a frequency-domain ...
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57 views

bilinear transformation

Recently, I came across this question in a paper to design a bilinear filter for certain frequencies. Interestingly, the pre-warping formula with $t=1$ turned out to be zeros because of the tangential ...
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69 views

Turn acausal Butterworth output into output of a causal Butterworth without input signal

I have a dataset which contains a large number of time-series which have been filtered with acausal Butterworth filters. For a real-time application, I can only use causally filtered data. Is it ...
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143 views

Filter design for frequencies in range 0-60Mhz

First of all excuse me for asking a seemingly vague question. But i am going nowhere in the problem i am trying to solve. I am working on a powerline communication system where i need to upconvert ...
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191 views

Demonstrating equivalence of correlation and coherence

I want to demonstrate the 'equivalence' of correlation and coherence. I generate two signals with a common known sinusoid buried in red noise, then compute their coherence spectrum. The bandwidth ...
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163 views

Implementing a phase-neutral band-pass filter using SciPy

Does the following code properly implement a phase-neutral band-pass filter using SciPy? ...
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107 views

Finding audio data in recording

I am trying to find a specific block of data that should hold valid audio data that I want to process. For instance, I record at 44.1kHz, but I only transmit a .5s of content. Since the buffer I store ...
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Multiple filters or not?

I'm processing audio signal sampled at 44.1 kHz. After some other processing, I need to filter the signal between ~5-50 Hz. Achieving this for a signal with such a high sampling frequency appears to ...
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501 views

bandpass implementing with DWT in matlab

In matlab help in find the implementation of bandpass as following ...
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Bandpass filter BPSK

I have a question concerning BPSK and the bandpass filter that seems to be sometimes placed before the receiver circuit (the receiver is a mixer and lowpass filter). Basically, from what I've ...
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What is the most efficient type of software bandpass filter?

I'm writing a C++ application to extract four modulated carrier signals at four separate frequencies, from a single input signal. I've designed four FIR filters at t-filter.appspot.com but they run ...
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367 views

SineWave generation and BandPass filter : Audio

Can any one suggest me a Bandpass filter in java which I would like to apply on generated sine wave of a particular frequency
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Feature Selection by Filtering

so there is this paper I'm reading and trying to understand fully: Towards Practical Identification of HF RFID Devices http://dl.acm.org/citation.cfm?id=2240276.2240278 I don't want to link the PDF ...
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Calculating a filter's attenuation at a certain frequency from the Q-factor

I'm using the Web Audio API to make a graphic EQ with four BiQuad filters; a highpass, two bandpass and a low pass: You can see each node representing each filter's frequency. It's working nicely ...
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298 views

Online filter for EEG

My goal is to build a real-time filter for EEG data. The data are being recorded in 512Hz and I wish to filter it (in a real-time, from 0.5Hz to 30Hz in the most optimal way). Unfortunately I'm not ...
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The transmitted signal of DPSK

I am very confused about how to get the transmit sequence of the DPSK signal. In my lecture notes, teacher give as the following example. ...
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239 views

What is the ideal FIR length, given a specific pulse length?

I am trying to ascertain what the 'ideal' FIR filter length should be, given the pulse length $T_p$ of a windowed sinusoid in noise that I seek to filter. As parameters into an FIR filter that I ...
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309 views

All-pass filters to remedy group delay

I would like to sum a filterbank made of bandpass butterworth filters to reconstruct an audio signal. Given group delays for each channel shown in the following plot . . . How would I go about ...
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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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Vocoder carrier wave bleed

I made a terrible vocoder earlier and got some help on it here: My vocoder sounds bad My new implementation is much better. I'm using the band pass filter described in the document suggested on the ...
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change the frequency component of a spectrum in an audio file

I am working on an audio dynamic range compressor using Matlab. After calculating the FFT of the audio file, I use several bandpass filters to amplify specific bands separately. What I want to do then ...
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What bandpass filter design will yield the shortest impulse response?

Designing a simple 2nd order IIR bandpass Buterworth filter with a centre frequency of 500 Hz and a 1 octave bandwidth gives me the following frequency response ... Now, if I take the impulse ...
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How can I break a filter down into second order sections?

This is a follow-up question of How do I apply a Chebishev filter? I designed a filter in Scipy: ...
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382 views

How do I apply a Chebishev filter?

I read a paper about a brain-computer interface. In this paper the authors reported "each signal has been filtered with an 8-order band-pass Chebishev Type I filter which cut-off frequencies are 0.1 ...
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Understanding a Bainter Circuit (chebychev filter)

As part of a class in Signal Processing, I am building a 3rd order Chebychev band reject filter. We implement this by using three cascading Bainter circuits. Although not part of the class, I have a ...
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When is aliasing a good thing?

In Hamming's book, The Art of Doing Science and Engineering, he relates the following story: A group at Naval Postgraduate School was modulating a very high frequency signal down to where they ...