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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What criteria should be used for smoothing

Actually I have some measurement which I want to get rid of noise I want to use different filter techniques but I am wondering what criteria I should use to check if I am removing noise or not or if ...
3
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29 views

O-QPSK constellation interpretation - GNU Radio

I am currently trying to recover the I&Q of a O-QPSK signal generate from the standard XBEE arduino module using a B200. I can get somehow get a "look-like" of a constellation. Here an ...
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39 views

amplitude at exact frequency in wide band signal

Could anyone suggest the most computationaly efficient method for finding amplitude of exact frequency having a noisy wide band signal. To be more specific about a task. I have some physical ...
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12 views

how to optimise the parameters of Savitzky Goly filter [closed]

Actually I would like to optimise the Savitzky-Golay smoothing parameters I would like to know if you have any solution in R or Matlab to share ? or if you have any idea about it
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1answer
28 views

Conditions for expressing a system as difference equation

I have read when studying this subject that a system is LTI and causal if and only if it can be expressed as a difference equation (if it is in continuos time, as a differential one). I don't know if ...
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1answer
36 views

Digital Filters deal only with samples, right?

I'm new to digital filters. So I'm trying to get things right and I can't find an explicit answer to my question on the internet. Question: Digital filters only accept samples as input? I mean the ...
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1answer
45 views

2-D Digital Signal Processing

I have been doing my research on 2D digital signal processing. What I am doing is about noise removal of digital image: Type of noise that I want to remove from an images is like the Gaussian noise ...
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23 views

How to recognize pattern in asymmetric signal [closed]

I'm trying to generate a trigger for every time the signal start showing those bumps (start is marked with the blue X). Has someone a suggestion? I tried the following approaches: Convolution ...
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1answer
34 views

Wavelet Fidelity Filter (video compression)

I have read a specification of Dirac (video compression format). A key element of this format is the use of the discrete wavelet transform. Section 15.6.3 of the specification defines individual ...
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1answer
42 views

Good Reference Problem to Test Filtering/Estimation Algorithms

I am looking to figure out if a current filter algorithm I have built could be useful for some problems I am looking into at work. It isn't a Kalman filter, but is instead making estimations using a ...
3
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0answers
50 views

How to remove a common noise signal from a set of signals?

I have 2D measurement results which seem to have a constant non-trivial background as shown here: For every column in this image, there seems to be a similar oscillation. I'd like to distinguish ...
3
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1answer
51 views

Estimation of accelerating target using position measurements only

I am currently thinking about approaches to estimating the position and velocity of an accelerating target. At this time, I have tried a few approaches that work alright. I have tried two variations ...
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0answers
35 views

Why pixels on image edges are shifted when using Wiener filter?

I implemented a Wiener filter using Matlab and i noticed that both functions(mine and matlabs) are creating an image with shifted pixels on the edges. Class teacher said it will happen. Is there a ...
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0answers
15 views

GPS signal acquisition

I have a set of GPS satellite signal data, the set is 1 ms long and has the information of two satellites (satellite number, code phase and frequency) buried in noise. This data has a carrier ...
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0answers
21 views

Filter Output Scaling

I am implementing a filter in hardware (fixed point). The filter has programmable coefficients - and due to this, the gain of the filter changes depending on the coefficient values being used ...
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1answer
43 views

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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1answer
44 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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2answers
63 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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2answers
34 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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1answer
25 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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1answer
50 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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1answer
20 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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1answer
36 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 ...
3
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1answer
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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1answer
55 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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0answers
39 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
72 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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0answers
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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2answers
63 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). ...
3
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1answer
52 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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1answer
65 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 ...
3
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1answer
47 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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1answer
43 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
55 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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16 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 ...
2
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2answers
42 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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1answer
32 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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0answers
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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0answers
43 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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55 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 ...
4
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1answer
103 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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1answer
87 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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26 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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1answer
26 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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0answers
42 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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0answers
44 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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1answer
41 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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33 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 ...