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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Removal of noise from vibration recordings

Problem I am analyzing accelerometer recordings that are contaminated by 'spikes' caused by issues in the digital circuitry. The spikes are problematic, because I wish to determine the peak-amplitude ...
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2answers
70 views

IIR filter implementation in Direct Form 2

I have implemented Direct Form 2 IIR filter. The input is the Kronecker delta function. I have written code for the response of the filter for Kronecker delta input. The code is: ...
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1answer
60 views

Plot the frequency response of MTI delay line canceller using Octave

I try to plot the frequency response of the delay line canceller (FIR filter which used for MTI). The delay line canceller has the following structure: ...
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0answers
31 views

Correct the phase of several damped sines

I have a signal $s(t)$ which consists of 3 damped sines it can be written as: $$ s(t) = A_1\sin(\omega_1t + \phi_1)\exp(-t/t_1) + A_2\sin(\omega_2 t + \phi_2)\exp(-t/t_2) + \\A_3\sin(\omega_3 t + ...
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0answers
17 views

How to use coefficients generated in c header file of fdatool in matlab?

I'm using the fdatool in matlab to design a high pass filter.I then generated the coefficients for direct form 1 structure.I exported it as a C header.The trouble is I have a vague idea as to how to ...
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1answer
26 views

Manual Extraction of Filter Phase Response with MATLAB using sweep sine

I'm currently at a loss for why my code seems to not be working. I'm doing a sine sweep on a filter to calculate its freq and phase response. The frequency response checks out, however the phase ...
2
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0answers
42 views

Matlab: Help in learning EKF

I have AR(1) model with data samples $N=500$ that is driven by a nonlinear input $x$. THe observation $y$ is corrupted with measurement noise $v$ of zero mean. The model is $y(t) = ay(t-1) + x(t) + ...
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0answers
18 views

Relation between Gaussian and Savitsky-Golay kernels

I would like to make a mathematical comparison between two methods in my field. One smooths with a Gaussian filter, and one smooths using a second-order Savitsky-Golay filter. Let's say the window ...
2
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1answer
157 views

How to test the FIR filter in C++?

I am almost done with design and implementation of my first FIR filter using C++. Its a Sinc-Windowed FIR filter designed for a cut off frequency of 100 Hz with sampling rate of 500, with a filter ...
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0answers
26 views

non-standard error function for adaptive filter

I want to create an adaptive filter. Its coefficients have this general shape: When the input signal for the filter is a sine wave, the filter behaves the desired way if the look-back window is set ...
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1answer
75 views

IIR low pass filter: floating point and fixed point

I have implemented an IIR low pass filter in direct form 2, the input to the filter is a unit impulse $\delta[n]$. I have calculated the output of the filter for the mentioned input using the ...
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0answers
14 views

Wolfram alpha, how to resolve term? [closed]

I like to resolve this term to w to obtain the resonance frequency dependent on the other variables. Does anyone know how to enter syntax correctly? ...
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1answer
43 views

Why should the cut off frequency and the transition bandwidth (BW) be expressed as a fraction of sampling rate?

I came across this confusion in Chapter 16,"Book - The Scientist and Engineers guide to DSP" and Topic is "Windowed Sinc-Filters". I am doing some calculations for designing the sinc filter and came ...
3
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1answer
68 views

sequence to perform filtering? which filter first?

Hi all Is there a generally accepted rule as to which order to perform filtering in? for example if I have three iir filters, a low pass filter a notch and a high pass filter, which sequence would ...
4
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2answers
613 views

What kind of filter is that? Is it IIR?

I am trying to answer the following question: Is the system described by $y[n]=0.5y[n-1]+x[n]-0.5x[n-1]$ an IIR filter? My answer is yes. Thank you
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3answers
101 views

when is a kalman filter different from a moving average?

this thread asks when a discrete-time Kalman filter is better/different from a simple moving average of the observations: ...
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1answer
30 views

kalman filter with time-varying noise?

in regular discrete-time (1 dimensional) kalman filter, it is assumed that we have white gaussian noise affecting the transitions and the observations: $x(t+1) = Ax + w$ $y(t) = Cx(t) + v$ ...
5
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3answers
140 views

How can I automatically identify and remove a fundamental frequency and all of its harmonics?

I have some microscopy data that is contaminated by a heartbeat artifact that I'd like to remove. The data consists of a large time series of images captured at ~60Hz. Here's a small example clip in ...
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0answers
9 views

Is a complementary filter usable with irregular readings?

I'm experimenting with a complementary filter for sensor fusion (the usual acc/gyro/mag). I've read whatever I could google, but two things are not very clear yet: (1) can a complementary filter be ...
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0answers
61 views

Time frequency domain analyis of signals

In the time frequency domain I have used the following denoising methods Thresholding or schwirnking - Soft,Hard,Median and with methods (minimax, adaptative and sure). However if recomposing the ...
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1answer
26 views

How to concatenate IIR filter (Butterworth) with a Matlab function and evaluate the integral

I have a function of $j\Omega$ and $v$ (velocity), i.e.: $$A(j\Omega,v)=\frac{(j\Omega)^2}{p + \frac{j\Omega}{v}}$$ where $p$ is the pole. I want know how $A(j\Omega,v)$ modify its behavior, when I ...
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2answers
38 views

Help me understand the phase of an FIR filter

I'm going over an exercise of designing an simple FIR filter, I have the solution in front of me, but I struggle to understand some parts of it. I'm asked to have an FIR filter with only 3 ...
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1answer
26 views

Obtain transfer function from signal flow graph

I have a pretty complex signal flow graph with all the blocks and the branches completely describing an analog filter, in the Laplace complex variable s. The signal $X(s)$ is the input and $Y(s)$ is ...
0
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2answers
61 views

Can someone please explain or describe me the behaviour of equation 2 in my question, relevant to filter response (Sinc Interpolation)

At present, I am learning the theory of operation of resampling for bandlimited periodic discrete signals using sinc interpolation.I am developing a design flow and having difficulty in understanding ...
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0answers
30 views

sgolayfilt function use the whole sgolay matrix?

I recently started trying to port sgolayfilt() from Matlab into my own c code. I realized through looking at the sgolayfilt function that it uses the whole matrix instead of the center row/column to ...
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31 views

Hints to solve this problem? DSP IIR Filter

I have this problem ... i need some hints to try to solve this... Can anyone guide me? Thank you in advance!
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47 views

filter out an expected but not regular signal

I am stuck with a case where I need to get rid of a portion of sinusoidal signal that suddenly appears in my main signal (sine wave). my total signal will look like: $ s(n) = \begin{cases} ...
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1answer
37 views

Confused about Hamming window and its relation with frequency response specification

$w(n)= 0.54 + 0.46\cos(2n \pi/(M-1))$ is Hamming window and we have say $fs_1$,$fp_1$,$fp_2$,$fs_2$ with pass and stop band tolerance specifications of the desired filter. From this specification can ...
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1answer
57 views

Ideal BandPass Filter

Let suppose x(t)=$\sum\limits_{k=-∞}^∞ R(t-kT)$ $R(t) = \begin{cases}1 &[0,2T] \\ 0 & \text{otherwise} \end{cases}$ x(t) is the input to an ideal bandpass filter with $\text{BandWidth} = ...
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1answer
39 views

Output of a band pass filter

Signal x(t) = | cos(2πft)|, f != 0 is the input of an ideal band-pass filter with bandwidth B = 3f/2. How can i Find the ...
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0answers
36 views

Find impulse response and frequency response through given filter [duplicate]

I cannot find anything truly helpful in my book, and I find mostly theoretical answers and not practical. So I am posting the exact exercise I want to solve, and through it I hope I'll work some ...
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44 views

Combine multiple FFT

I have been acquiring data through ADC and into memory, the input signal are square waves that step down in frequency as time goes by. Due to memory, I have a fixed maximum number of samples per FFT. ...
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1answer
63 views

Question regarding filter implementation - Audio EQ Cookbook

Some of you may know the infamous Audio EQ Cookbook. You can take a look here. We tried to implement the functions there to achieve a implementation for a Lowpassfilter. However, when we try to ...
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2answers
44 views

Is DCT basicly a filter?

I am reading about audio processing for my university project and I found out that DCT basicly filters out some frequencies. I wanted to use for example high-pass filter and then DCT for compression, ...
0
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1answer
26 views

Concept of combining multiple FIR Filters into 1 FIR filter

I try to combine my 7 band FIR filters into 1 FIR in order to process an audio signal. I use convolution to combine their coefficients but the effective is not the same as I apply 7 different FIR ...
5
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1answer
105 views

Duration of unknown rectangular pulse with additive white Gaussian noise

Problem. There is a discrete signal $f[i]$ (example below). It is known, that $f[i]$ have a form of rectangular pulse with additive white Gaussian noise. $f[i] = s[i] + n[i]$, $s[i] = ...
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0answers
26 views

Noise Removal from an image

What type of filters can be used to remove Poisson noise in an image? I tried applying Gaussian filter to few points in the spectrum.
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1answer
37 views

All pass systems- Poles and Zeros

If an All Pass system has poles at $0.8\exp\left(-j \dfrac{\pi}{4}\right)$ and $0.8\exp\left(j \dfrac{\pi}{4}\right)$, There would be $2\pi$ jumps in the phase (principal value) at angular frequency ...
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0answers
32 views

Applying a custom filter to FFT results?

I think I am missing something here and I do not quite understand why. Background: I am collecting quadrature signals from a software defined radio. There are two signals, the I, and the Q which is ...
0
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3answers
91 views

In filter design, why isn't it possible to have a frequency response with phase 0?

A linear phase filter will cause a delay in the output signal of the filter. If I'm not mistaken, a filter with phase equal 0 would cause no delays in the output signal. Can someone explain me why ...
0
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1answer
61 views

Allpass filter feedforward/feedback design and code

I want to design/implement a simple feedforward/feedback all-pass filter, and I am having some troubles and questions with it. From Shroeder design (based on J. Smith article here): I came up ...
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1answer
43 views

pre-emphasis filter - parameter a

Can someone give my a link to study to solve this problem. I can not find any formula for this problem... Suppose we filter singals with the below pre-emphasis filter: $y(n)=x(n) - ax(n-1)$ How can ...
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1answer
36 views

Fast/efficient way to compute Laplacian edge enhancement filter

I would like to implement a somewhat smarter Laplacian edge enhancement convolution. Right now it is implemented as (generic 3x3 convolution): ...
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0answers
27 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 ...
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1answer
34 views

Filtering Passband Signals using Complex Baseband Filtering

So I'm given a pass band filter with specific transfer function $H_p(f)$, I want to implement this via baseband processing. I already know how to take the input signal $u(t)$ and process it such that ...
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1answer
29 views

Linear Regression Filter Properties

I have a filter to detect when a slow moving signal (oven temperature) reaches steady state. I am using a linear regression of a moving window and looking at the slope. Based on the equations for ...
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1answer
26 views

Problems filtering image with prewitt

I'm trying to filter an image vertically to get the edges, in MATLAB, but I get very different results from convultion and correlation. CODE: ...
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1answer
24 views

Estimating Velocity from Fuzzy Position Data with Known Uncertainty

I was wondering if someone could maybe clarify or direct me to the best answer for this question. I want to estimate velocities from position data. However, the position data is fuzzy but I have an ...
0
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0answers
66 views

bandpass FIR filter

I need to make simple bandpass audio filter. Now I use this simple C++ class: http://www.cardinalpeak.com/blog/a-c-class-to-implement-low-pass-high-pass-and-band-pass-filters It works good and cut ...
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31 views

Filter sharpening; a stub

Filter sharpening is a technique to sharpen the magnitude response of a digital filter. Finding information online about it is problematic since almost all google hits will be about image sharpening ...