In signal processing, a filter is a device or process that transforms a signal by selectively choosing specific frequencies and leaving others with appropriate gain or as it is.

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Basic FIR Filtering with audio buffer in C++

I am willing to implement a basic FIR filter using C++ and JUCE. I wrote this simple algorithm using the information I found in the DSPGuide, but I only seem to get a variation in volume for all the ...
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37 views

Response of cascading FIR filters

I can't seem to get the right answer for this. Could someone show me the procedure? As shown in the figure a system is constructed by cascading four FIR filters having the following frequency ...
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52 views

How to plot magnitude and phase response by hand if I have the Transfer Function?

I have the transfer function of the system, which is: $$H(z) = \frac{1-z^{-1}}{5(1+2z^{-1})}$$ How do I sketch the magnitude and phase response? I'm sorry for the bad formatting, it's my first time ...
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32 views

Bandpass Filter Order vs Sample Numbers of Noisy Signal

I'm working on signal filtering in MATLAB. i wrote sample code that generate 50 Hz signal with some noisy frequency and use Kaiser bandpass filter to get only 50Hz frequency. this code work great! but ...
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24 views

How are these pole zero plots created

Back around 5 BC, where C stands for the programming language, engineers would photograph their oscilloscope's display to record their test results. This appears to be such a photograph, taken from ...
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35 views

Calculate Q factor of a Low Shelf and High Shelf filter

I'm developing an app that has an EQ using eq10q plugin. My eq has 10 bands. I'm using peaking filters for the middle bands and a low shelf filter for the first band and a high shelf filter for the ...
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Plotting band-pass filtered signal of an audio in MATLAB [closed]

I am new in MATLAB and try to plot some form of an audio file and I have managed to open and plot in time domain and FFT using the following code: Step I: Opening the Wave File ...
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18 views

How to set a Carrier Wave for DBPSK Modulators in gnuradio?

for a Project I need to build an Audio Modem in GNU Radio. I decided, that it would be the best to use DBPSK Modulation, because that is fast and relatively noise resistant. But as it seems, the ...
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34 views

Should the order of a filter be proportional to the sampling rate?

I have designed a fir filter with my desired frequency response at a specific sampling rate and filter order. If I were to redesign my filter for a new higher sampling rate, should I change the filter ...
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27 views

What dictates the phase response of FIR filters when considering its zeros [closed]

I assumed an even tap filter and i got a pole at $z = -1$ and an odd tapped filter (assuming the middle coefficient is zero) gave me poles at $z = -1$ and $z = +1$. This was confirmed by the theory ...
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30 views

Can we determine if a filter is butterworth or chebyshev from its physical topology?

Can all analog filters be classified as Bessel, Elliptic, Butterworth or Chebyshev? Given a physical ladder topology of several stages of {L, C or LC} in {series or parallel}, is it possible to ...
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53 views

How can a signal have two maximum frequency components?

$x(t)$ can be exactly reconstructed from its samples at $\omega_s = 10 \textrm{ rad/sec}$. My conclusion is that the maximum frequency component in $x(t)$ is $5\textrm{ rad/sec}$. But I'm being told ...
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38 views

EQ filter implementation

I am writing a simple EQ filter for my audio player. I got one working with Biquads (single stage 2nd order or double stage 4th order). The app is written with Qt so I also checked QMMP (Qt based) ...
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3answers
68 views

Question on FIR filter

I've been trying to do this problem for the last few hours. Could someone show me the workings on how it is done? Not just the answer. The figure shows the structure of a FIR filter where $A = ...
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26 views

Unique signal extraction from a cumulated signal

I'd like to start off by saying that I am not very experienced at signal processing, so I apologise in advance if I do not explain everything properly the first time. I would like to analyse the ...
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25 views

Is it possible to rewrite gradient magnitude of Sobel in continuous formula?

Let $*$ denote a convolution operation, $G$ denote a kernel, and $I$ is a given image. The gradient of the image $I$ is equivalent: $\nabla (G*I) = (\nabla G) * I$ The Sobel filter approximtes two ...
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60 views

Filter Design in Matlab

I want to design a filter to remove all frequency components from a .wav file except those within $\pm 25\,\text{Hz}$ of $523\,\text{Hz}$ as well as its harmonics (up to the Nyquist frequency). ...
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18 views

Plotting Filter Transfer Function (Matlab) [closed]

I want to plot the absolute value and the argument for the following transfer function around $\nu = 400 \ Hz$. The filter has impulse response: $ h(t)=50 u(t) \exp(-10t) \sin(2 \pi 440t).$ (The ...
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26 views

Amplitude Demodulation using RC low-pass filter in matlab [closed]

I am working on an Amplitude modulation and Demodulation assignment, which has some required waveform. I am facing problems with demodulation. I have amdemod and ...
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48 views

Filter for noisy accelerometer data

I tried to read up and get a filter for a 3-axis accelerometer but this is more confusing than I thought. I have an IMU with a 3-axis accelerometer on the end of a robot link which is rotated around ...
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59 views

Slope of 2nd order low pass vs band pass Butterworth filters

I have noticed that some manufacturers of audio processing products label a 2nd order Butterworth low pass as having a slope of 12dB per octave, but then also label a 2nd order Butterworth band pass ...
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38 views

Extended Kalman filter - why not use a 2nd order Taylor expansion?

I'm implementing my first EKF and using a Taylor expansion to linearize the model. I'm somewhat new to this. Based on a paper I've read, I'm attempting to linearize the state transition matrix using a ...
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36 views

Looking for low-noise audio data to benchmark some noise-processing techniques

I'm looking for a source of very low-noise audio data for use in benchmarking various methods of random noise correction methods. My intention is to have a very clean signal to which I can add known ...
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1answer
47 views

Kalman filter - nonlinear measurement model

I'm new to Kalman filters and estimation in general. I'm running a simple test of an EKF to check my understanding, but I'm getting some odd results with a particular case. Given a state vector: $$ ...
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15 views

How to design Bi orthogonal wavelet filter bank

I know in orthogonal wavelet system analysis filters can be made by flipping the synthesis filters(vice versa) but in bi orthogonal system this will not work because the co efficient are symmetric in ...
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39 views

detect to rising, stable and falling point in non-smooth rectangular wave

I am working on basic signal processing problems in MATLAB. I have found a signal from the internet (i don't remember the site exactly). The data is organized in column wise. 1st and 2nd column is ...
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31 views

Extended kalman filter for linear system

I studied about Kalman filter(KF) for about a week. And I understand that Kalman filter(KF) is suitable for linear system and extended Kalman filter(EKF) can be used for nonlinear system. However, I ...
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21 views

Feature maps for a Convolutional Neural Network

I hope this is the right place to ask this, so here goes: I am currently trying to implement a convolutional neural network in C++, but since I have no formal education in signal processing, image ...
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38 views

plotting frequency response to window sinc funtion in matlab

I am taking DSP and the instructor explains theory, but has not shown a single example all semester. One problem on the current homework assignment is to plot the frequency response of a windowed sinc ...
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53 views

Using a median filter to constantly monitor to identify a laser strike in any of the known laser wavelengths

We would like to design a proof of concept using a flight simulator cockpit similar to one that flies with passenger to prototype a system for blocking coherent laser pointer beams aimed at commercial ...
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94 views

Notch Filter - Bandwidth vs pole / zero location vs Q factor

I am reading up about notch filters. I understand the closer the pole is to the zero, the narrower the width gets and thus the bandwidth gets smaller. Is there an equation that links the bandwidth to ...
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70 views

How to remove noise using mean and median filters?

I can remove the noise using moving average filter. The MATLAB code is shown bellow. But how can I remove the noise using mean and meadian filters?
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21 views

Methods of combing two parameter estimates

If you have two different methods of calculating a continuous parameter (eg. heart rate), each with their own uncertainty, what would be some common methods of combining these parameters to create a ...
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22 views

Calculate 2D Windowed Sinc Kernel

I am implementing a Windowed Sinc Filter for Scaling images by the factor of 2. Therefore I need to calculate a Filter Kernel. I already know how to calculate the kernel including a Blackman Window ...
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23 views

Evaluation of Autocorrelation and Power Spectral Density of white noise through a filter

So say there's a filter with an impulse response of $h(t) = (0.8)^t u(t)$. I'd like to pass white noise through this and figure out the autocorrelation and power spectral density of the output. I'm ...
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40 views

Choosing correct filter parameters for IMU sensor datas

I have a IMU sensor breakoutboard using ITG3701, LSM303D LinkProduct. This involves accelerometer, gyroscope and magnetometer. I have connected the sensors to a Arduino and sending the datas to ...
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41 views

Combining IIM and MZT transformation

Split from thread: Correcting Impulse Invariance Method Back to this subject. Matt L suggested combining IIM and MZT b-coeffs to get the filter response improved at hihger frequency area. Couldn't ...
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40 views

Shall a $1^{\rm st}$ order IIR filter include $x[n-1]$ term?

I have seen a $1^{\rm st}$ order IIR filter in the following form: $$y[n] = \alpha x[n] + (1 - \alpha) y[n - 1]$$ Such as: another post in this forum However, the filters generated by Matlab, such ...
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29 views

Amplitude/phase recovery on noisy signal

I have a noisy signal that has an ac component of fixed frequency but variable amplitude and phase. I'd like to recover the ac component. The signal (blue trace) is mostly smooth, but has a few ...
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22 views

Adjusting corner frequency to constrain maximum disturbance in a high-pass filter

I have a first-order high-pass filter with transfer function: $$G(f)=\dfrac{G_0 jf}{jf + f_c}$$ where $G_0$ is the gain at high frequencies. If I input a sine wave with frequency 1 KHz and I want a ...
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Are wavelets for audio spectrograms available as a simple FIR filter?

I have read that "Debauchies Wavelet is simply a short FIR" so i am searching for a single FIR that i can make into a filterbank, a precise "bandpass filter" that detects narrow frequencies, i.e. 1Hz ...
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94 views

Biquad Filter Optimization

I would like to try optimize a bit more the biquad filters indended for RIAA/non-RIAA equalization at low samplerates (44.1/48kHz). Best fit I get now is little below ±0.3dB for 44.1kHz and below ...
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1answer
47 views

What filter to use in audio analysis filterbank instead of FFT?

Standard bandpass filters can make super precise analysis filterbanks with 1024 to 4096 filters, on reaktor4. I tried in code to used cookbook BandPass and the result was aweful. Does someone know a ...
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40 views

How can I shift this signal to it's midpoint in order to decode it

I'm wondering if there's a simple way to decode this pulse signal as I'm reading it in. I'm thinking the simplest way to decode this is if i can shift the whole signal down so that it's centered ...
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1answer
33 views

Real digital filter property

I am a beginner to study about the filter notion and property Being a real digital filter, (here "real filter" I means that its impulse response is real-valued) this formula is established. But I ...
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3answers
151 views

How to design very narrow, sharp lowpass filters - Only DC needed?

I asked exact the same here one year ago: One year ago question I asked this question again here, because after one year, I have learned more about DSP and am thinking ways to improve it. Filter ...
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s_to_z (Pupalaikis)

Paper: Bilinear Transformation Made Easy - http://documents.mx/documents/easybilinearpdf.html Example of implementation - http://codepad.org/u3tvKn0S I get the same output for Butterworth lp example ...
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69 views

How does an Image filter really sweep an Image?

Suppose, we have the following image: Now, we want to apply a 5x5 filter to the image. How would the filter sweep the image? Like this? Or, like this? Or, anything else?
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73 views

Determine whether a signal is increasing or decreasing over time

I have a signal (x-axis: Time, y-axis: Data) which has more than 10000 samples per second. The signal itself represents some physical data (e.g. speed, acceleration, etc.) and has some noise on it. ...
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30 views

What is the difference between MRF and Total variation in noise removal?

I have a general question in image processing. I have a noisy image. I would like to classify the noisy image into some regions. Two famous approaches I can use are: MRF/Gibbs MRF: Model the spatial ...