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# Questions tagged [filtering]

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320 views

### Overlap/Chunk processing possible with Zero-phase?

I'm relatively new to DSP and I'm currently investigating FIR filter and IIR filters. From what I've found FIR filters can be implemented efficiently using the overlap-save method, but I was wondering ...
2k views

### Implementing a 2d butterworth filter for image processing?

I am at the moment trying to implement a bandpass butter worth filter which i then can use to apply on my original image. Problem is though My implementation of it using OpenCV doesn't seem to be ...
60 views

### Why Would Pre Filtering Measurement Data Affect the Least Squares Estimate?

In estimating parameters in a discrete time model I've often seen the use of filters applied to the input data, before its applied to least squares processing. I've been told that the filters are ...
2k views

### Derive velocity and acceleration from position

I generate random spike data that represent the ouput from a rotary encoder. Here the output of my algorithm: The first plot is position, then velocity and then acceleration. Even though I downsample ...
85 views

### Filtering performance on Poisson noise with quadratic data-fidelity

We recently performed a work on signal filtering/component separation (sparse signal/trend/noise). The cost function contains: A quadratic data fidelity term, Some smoothed $\ell_1$ terms for ...
329 views

### How is the ends of a bandpass filtered signal reliable after applying the cosine taper?

A taper function decaying to zero at ends such as a cosine window is routinely applied to the signal before bandpass filtering to reduce end effects. Obviously the window alters the waveform. So, as ...
871 views

### Optimal windowing strategy for filtering live signal

I have a stream of 250 samples per second arriving at a pipeline stage which looks something like this simplified example. ...
2k views

### What is a 'notch' in image processing?

I cannot find out what does "notch" means in image processing? We have selective filters that one of the best of them is Notch filters. but what does the concept of "Notch"? why they are called "...
36 views

### How to reconstruct the signal if there were some temporary offsets

I am not a signal processing expert. I have data like this: where the red is what I have and the black is what I want to have. Any idea how to reconstruct this? The code for generating the data is ...
45 views

### Adding channel effects to a signal

I have a a channel matrix "H" that is circulant. I have data blocks. I want to add the channel effects to the signal. When H was only a vector of channel coefficients I would say: ...
452 views

### What is Single pole filter?

Can anybody tell me why do we use single pole filter? And may be an example of Single pole filter in matlab. Good literature recommendations are also welcomed.Moreover, that would be good if anyone ...
27 views

### If a signal is added to another in the freq. domain, how to filter it out?

I have two signals, $x$ and $y$. I know that $F(x)=F(s)+F(n)$ and $F(y)=F(n)$, where $s$ is the 'clean' signal, $n$ is the added noise and $F$ donate Fourier Transform. To obtain the clean signal, I ...
89 views

### Can filter “depth” be adjusted by mixing dry and wet signals?

Can filter "depth" be adjusted by mixing dry and wet signals? I.e. can I simulate e.g. a +6dB bandshelf/peak filter at 1kHz by mixing in some of the dry unequalized signal and some of a wet signal ...
1k views

### MATLAB : How to filter a data signal

I have a data signal (column vector) with N values taken over at specific sample rate (dx) at a fixed frequency. After taking the Fourrier transform of this signal and representing it in the Fourier ...
2k views

### Filtering out a specific frequency in an analog signal

I'm wondering how I would go about filtering out a regular sine-wave signal with a constant frequency and voltage. I'm really new to the whole DSP-area but imagine I would have a regular sinewave at ...
587 views

### What is pulse train filter?

I have recently seen some code written in modelling tool like Simulink, ASCET which uses PT1 filter? Why do we use a pulse train filter? What is the difference between FIR, IIR, Chebyschev, ...
44 views

### Texture-like measures for quantifying density of data in binary images

Consider the following black-and-white image. It depicts a freehand sketch. I wish to characterize the "density" of sketch strokes. For e.g. the hair strokes are densely grouped together. So are ...
117 views

### Contour based blurring

Suppose I have an image of a cat and a binary mask image corresponding to cat's location as shown I would like to blur the image region surrounding the cat but as a function of distance from the cat'...
7k views

### difference between mean filter and order statistic filter

I am working on my paper about comparing between mean filter and ordering statistics filter, The mean filter is contraharmonic mean filter and the ordering statistic filter is alphatrimmed mean filter....
646 views

### Discrete Sinusoidal to State Space

I'm looking to apply an optimal LQR filter to a discrete signal of the form $x[n]=A\sin[\omega_0n + \phi]+ v[n]$ The amplitude $A$ and the phase $\phi$ are unknown variables I want to estimate using ...
171 views

### MATLAB, recover a signal that has a cosinusoidal interference and that has been AM modulated

I have a signal which has been AM modulated but the channel also added a cosinusoidal interference A cos(2 * Pi * f0 * n * Tc + Phase), at the same ...
7k views

### How to Calculate Gaussian Kernel for a Small Support Size?

How to calculate the values of Gaussian kernel? I think I understand the principle of it weighting the center pixel as the means, and those around it according to the $\sigma$ but what would each ...
158 views

### amplitude compensation after filtering and mixing audio

I am working on a mixer which lets me mix dry and wet signal in a user defined ratio. Wet signal is basically just the all pass filtered signal. The mixing takes place in frequency domain and so does ...
902 views

### How does kernel work in unsharp masking?

I applied the kernel below to the picture for unsharp masking k = [-1 -1 -1; -1 8 -1; -1 -1 -1] I got ! Then I changed 8 to 14. And I got How does kernel work ...
2k views

### low pass filter with minimal ringing

I am trying to filter out some square wave signal to within a limited band (1/4 or 1/8 of the original), I realized that there's a lot of ringing in the wave when I use my filter (elliptical), I also ...
175 views

### Matlab: is a highpass filter what I want, to obtain my required spectrogram? How do I design/apply this? (pic included)

The axes are wrong in the spectrogram. I have an audio wav file, and I know the sampling rate. this is read into the audioData variable. The audio is 1 channel. selected window length I believe (can't ...
54 views

### Nonlinear tricks for blocking wide band noise

Conventional methods of filtering allow one to block parts of a frequency band while passing others. But thinking outside of conventional means, and perhaps not based on any frequency methods at all, ...
655 views

### filtering in frequency domain

I am performing decorrelation of two channels of audio using all pass filtering. The two all pass filters for two channels are of very high order (>1000 but with not all coefficients non zero). I have ...
118 views

### Notch filtering line noise outside of frequency band of interest

Practically speaking, if one is interested in a frequency band well-separated from the line noise (say, for example, the 10-20 Hz band, with 60 Hz line noise), would it be advisable to notch out this ...
54 views

### LPF - signal values unaffected at specific times

Is it possible to design an LPF that has an output identical to the input at specific points in time domain (the rest of the input waveform can get filtered/distorted)? Is there a general name/...
127 views

### Fractional equalizer with non-integer oversampled signal as input

I would like to know how the output sequence from a fractionally spaced equalizer, with a non-integer oversampled input signal, is generated. For example, for $T=T_{sym}/2$, my actual code is ...
231 views

To obtain the gradient from an image, one can use a linear filter that for example is derrived from the derrivative of a gaussian. Then convolving the image with this linear filter gives you the ...
836 views

### Equalizing $1/f$ noise

I am recently acquiring data through ADC on signals ranging from $0.1\textrm{ Hz}$ to $50\textrm{ kHz}$ ($F_s = 128\textrm{ kHz}$). I noticed that apart from the white noise, I have something similar ...
358 views

### Use Scale Space Representation to Filter Single Image

Currently I hope to use scale space representation to filter one image. Features in one image can be filtered using an Gaussian smooth filter with one optimal sigma. It means different features in one ...
451 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 ...
163 views

### Adaptive Line noise removal using IIR notch filters

I'm trying to filter out line noise(60Hz and 120Hz) from a EEG signals received over a bluetooth link. I'm proposing to use a IIR notch filter to filter out the line-noise which varies w.r.t to ...
682 views

### Filtering Overlapping Frequencies in sound file

I have been given a sound file of a plane passing over a rain forest filled with birds. I am supposed to filter out the sound of the plane as it flies over. I've accomplished this with various types ...
142 views

### Band-pass filtering on whole signal or overlapping chunks?

I am working with a signal acquired by a pulse oximeter, i.e. a device that records the change of light intensity reflected by a specific tissue depending on its blood perfusion. Since I am interest ...
2k views

### Butterworth filter in python

I'm trying to use a Butterworth filter in Python as described in this thread with these functions: ...
138 views

### Why is successive decomposition of a signal performed only on low pass component?

The question says it all. In typical (wavelet-like) decomposition of a signal, why is only the low pass component chosen for successive decomposition ?
56 views

### Different results for seperable filtering v/s direct filtering on 2-D image in MATLAB

I compared the difference between seperable and direct filtering for MATLAB's cameraman image. The difference is huge. I would like to understand the reason for this. Code below. ...
2k views

### Can the order of filtering and downsampling be exchanged?

Say for example, I have a signal with maximum frequency at 600Hz, and I originally oversampled it at 2000Hz. Afterwards I was only interested in frequency less than 500Hz. I guess I could first filter ...
931 views

### Instantaneous power estimation by discrete hilbert transform - how far does it smooth?

In my research area, instantaneous power in a specific frequency band is commonly estimated by the following procedure: Apply a bandpass filter on the raw signal (e.g. 80-90Hz bandpass). Estimate ...
121 views

### Any way to compensate for fractional delay filter's weakness between taps?

A little background: I have an FPGA (running at 200MHz) that I am creating multipath events using buffers, all of that works. I take RF, mix down to IF, sample, make adjustments, out the DAC, and ...
4k views

### Removing transients in highpass filtering with MATLAB

I've made a simple first order IIR highpass filter with a zero at z = 1 and a pole at z = 0.9. Its frequency response looks like this: Now, I filter a DC signal using this filter. Here's the MATLAB ...
633 views

### How to design a filter with a certain magnitude response

I am trying to design a filter whose magnitude is the same as that of a given signal. The given signal is wind turbine noise, so it has significant low-frequency content. After designing the filter, I ...
695 views

### MATLAB filter not attenuating enough

Currently, I'm working on removing 50 Hz power line interference from an ECG signal. Before trying out notch filters, I decided to try out a simple lowpass filter with a cutoff less than 50 Hz. Here's ...
202 views

### Extract signal from big gaussian noise

I have signal, periodic with amplitude 10 with frequency about 10 kHz. It is hidden in Gaussian noise with standard deviation 100. Some idea how to extract periodic signal? Thanks in advance.
I need help solving the following blurring function question.Assume an image $f(x,y)$ is moving in front of a camera so that $𝑥_0(𝑡)$ and $𝑦_0(𝑡)$ are the time-varying components of motion in the ...