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# Questions tagged [filtering]

Filtering is a way to process an input signal so that the output signal has interesting features enhanced or unwanted features reduced.

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### Explanation to layman on the effect of zero-ing in frequency domain

Unable to understand the answer to Why is it a bad idea to filter by zeroing out FFT bins?. Please elaborate and explain in layman's term what the answer is saying. Also by any chance is it related to ...
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1 vote
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### Calibration/Filtering Order

Let's suppose we have a stream of data from a 3-axis sensor like a MEMS magnetometer. Each of the sensor's axes have an output bias, gain, and misalignment (all axes should be orthogonal). ...
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### The order of filtering and convolution

Assume I have a source signal s(t) to pass through a system. I record the signal at system output place, which is denoted as d(t)...
71 views

### Removing rotational frequencies from a signal

I have a torque signal from an experimental adapter which measures based on strain gauges. Turns out that my signal presents very strong oscillations at the same frequency of rotation, which very like ...
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### Why Ando operator is worse than Sobel operator when computing gradients in my case?

I am testing different gradient operators for 2D images. I have some differentiable function (let it be $f(x,y) = \sin(2x) + \cos(3y)$). I discretize this function (i.e make a 2D image of it) and then ...
1 vote
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### Using the Dirichlet kernel as a lowpass filter

I have a question about using the Dirichlet kernel as a filter. Let us suppose that I have samples of a continuous function sampled with frequency $F_s=10 \,\texttt{Hz}$. The function is band-limited ...
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### Border effects / artifacts for spectral filtering of images

I am working on a spectral filtering problem as follows: I'm given an image with a periodic distortion pattern (see below), and I want to remove the distortion pattern while preserving the main ...
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### Sample rate of digital modems--how do they do digital filtering if sampling below Nyquist rate?

I can't find this answer anywhere. I have a couple satellite modem manuals and they refer to digital filtering functions that they do, but they say almost nothing about their sample rate. I always ...
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1 vote
1k views

### Understanding the Farrow Filter

I found the following diagram of a Farrow Filter online: As far as I understand the purpose of a Farrow filter is to interpolate samples at a fractional ratio. For example: we have an ADC sampling at ...
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### How to apply a delta-filter

I'm trying to apply delta filter to remove pre-fault conditions from my signal. It is formed by a vector (7680x1), the signal was generated at 60Hz and has 32 samples per cycle lasting 4 seconds. The ...
1 vote
156 views

### What is the best method to filter a signal where baseline and the signal of interest have overlapping frequency range?

I am reading out the movement of a motor arm using a Hall sensor and a magnet pair. The hall sensor measures the distance between the sensor and the magnet. The motor arm is being moved with a band-...
57 views

### How does the sampling rate of a digital filter limit the sampling rate that can be used for replay of filtered signal?

I need a band-limited white noise to characterize a biological sensor that senses mechanical movement. For that, I am generating a Gaussian white noise (MATLAB Communications toolbox) of length 10 ...
101 views

### How do I isolate a part of this signal in time-domain in Matlab?

I want to isolate a reflection part of a signal which I've transformed from Frequency to Time-Domain (see Picture). So far, I've tried to create a Hamming-Window with the specific window-width for the ...
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### Specific de-trending method for damped oscillation?

Say I have a set signals consisting of damped harmonic oscillations, that I want to extract the characteristics of with the prony method. In the datasets I'm working with, it is possible for these ...
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### Sample Use vs Sampling Frequency

I need to acquire an analog signal via an ADC and send it via a digital communication line (CAN bus) with a given frequency $f_{send}=100Hz$. If I understand correctly this means that this constraint ...
232 views

### "Tone Control" IIR filter coefficients

The documentation for Analog Device's sigmastudio shows some of the formulas behind their biquad IIR filter coefficients. The usual suspects (HP, LP, peaking, ...) as described in RBJ's cookbook are ...
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### Implementation of an IIR filter with integer coefficients

I'm trying to figure out the implementation of IIR filters with integer coefficients, but I've run into a problem that I can't figure out. There is an excellent post on this topic, and I took it as ...
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1 vote
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### Filter a 1D time series taking advantage of accuracy values for every data point

I have an assignment on a time series that contains the x positions of a point in space. This series comes with another one of the same length, where every element goes from 0.0 to 1.0 and represents ...
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### How to demodulate a bit sequence that is offset-modulated with a complex exponential?

I have a discrete-time complex exponential $a[n]*(\cos(\omega*n/N) + j \sin(\omega*n/N)) + b[n]$ where $a$ is constant and $b$: $\{0,1\}$ So it is basically an offset-modulated sequence of bits and I ...
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### Using python to remove Gaussian noise and a high frequency signal from a audio file

I have an audio file where people are talking, and Gaussian noise and high-frequency signals have been added to the file. My goal is to remove the noise from this file using Python. For this ...
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1 vote
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### Transmitting data with QPSK using an SDR

My question assumes that I want to transmit some data using QPSK using and SDR. The SDR will be fed with IQ data and this will transmitted at a sample rate Fs and be up converted to a carrier ...
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50 views

### Characteristics of linear systems in the time and frequency domain

Why is the output signal obtained through frequency response different from the other two. ...
155 views

### Filtering in time domain vs filtering in frequency domain

The signal is an impulse repsonse. I am filtering the signal using a windowed sinc filter in both frequency and time domain. I am interested in knowing the differences between the two methods and ...
374 views

### What's the point of differential beamforming?

I recently got into differential beamforming, in particular into the work of Benesty and Cohen. It seems to me that differential beamforming is something that just "takes place" when ...
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### Upsampling of a signal

A low-passed signal, bandwidth limited to 4KHz is originally sampled 10 KHz. If I want to resample it at 20 KHz, I take these steps. Are these correct? Am I missing an step? First we need to filter ...
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1 vote
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### How to get an impulse response of a MIMO system?

So I have data vectors from a MIMO system and I wish to see the impulse response Any idea how I can proceed with this?
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### What does a Gabor filter "filter" out?

Almost all of the searches online have returned results related to image-processing, but I am looking for a more rudimentary example with some physical intuition (eg; a high-pass filter only lets the ...
1 vote
475 views

### Why does convolution give the output of a passing a signal through a filter?

I have a rudimentary understanding of Convolution, the Convolution Theorem and why the output z(t) of an LTI system can be found using the convolution of input signal x(t) and the impulse response h(t)...
62 views

### single tone -> multi bandpass filter -> incorrect output

background: Trying to filter out all other signal frequencies except -> signal whose frequency can be in multiple's of 16Hz {16,32,48.......160]. so started experimenting with a single tone [no ...
1 vote
315 views

### How to recover the LTI system step response by the known output and input signals?

Having the input signal as a step-like pulse and the output as its distorted version after passing through the system: is it possible to somehow recover the step response of the system? In the Figure ...
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### ICWT filtering signal with a cut-off frequency

In ssqueezepy, by finding a certain scale is it possible to do an icwt only for the scales above (or bellow) ? For exemple if I have a double sin (with $f_1$ and $f_2$), by taking the frequency $f_c$ ...
1 vote
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### Does filtering by wavelet decomposition and reconstruction introduce a phase shift in the filtered signal?

I am removing low frequency noise from a signal using Matlab using the DWT and then reconstruction at a specific level: I am removing the approximation signal at level 10 which approximates the low ...
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### How to find system output by its step response?

Inspired by this post, I tried to reproduce the procedure described in the answer in Python considering rectangular pulse: ...
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### What is the necessity of shifting the impulse response of a filter to the front of the time domain buffer and windowing?

I was reading the answer to this question provided by Phil Karn. In the answer, it has been said: Ensure that the impulse response of your lowpass filter is shifted to the front of your time domain ...
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### How to estimate the local trend in a signal?

I need to remove trend from my time-series which looks like the following images. However, I want to estimate the trend before removing it. Hence directly removing it won't do it. The simple ...
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### How to achieve a DC portable power source with low noise in 400 MHz frequencies

I am working on an SDR composed system that is plugged into a Raspberry Pi board powered by a 5V DC Power bank. The SDR is configured to measure a signal around 400 MHz. The noise floor measured by ...
186 views

### What does frequency filtering actually practically mean?

I've got an electronics circuit which was filtering between a Passive HPF stage (1uF and 330K) and an Active LPF stage (4.7uF and 10K). As you can see it was filtering between 0.48Hz and 3.38Hz, and ...
100 views

### Method for splitting time-sampled signal into two signals

Update: the yellow area in the graph below can be ignored, it shows power produced. I'm only interested in the blue line, and how to separate power consumed by the heating system from the rest. I have ...
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