# Questions tagged [scipy]

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27 views

### Find the equivalent of this python remez specs in C++ remez or Matlab firpm

I want to start with that I am quite new in this community, so if this question does not belong here, please point me to the right place. Thank you! Background I am learning and writing a half-band ...
16 views

### Help with setting up transfer function correct format

I have a transfer function as: H(s) = R / (sRC + 1) V is the output and I is the input so we can write: V(s) = I(s)*H(s) Now the thing is that, I want to obtain I(t) for the given V(t). So I write: I(...
33 views

### Evaluate filter matlab function on scipy

I want to reproduce the result given by filter() MATLAB function using scipy.signal functions. The result is not consistent: Matlab example: ...
34 views

### How to specify parameters in scipy.stft to reproduce published analysis

I am starting a project on this Keggle dataset containing EEG registrations (sampled at 128 Hz) of several subjects. What I am really interested in is the final ...
23 views

### Unexpected results of deconvolution with scipy.deconvolve

Below I have plotted the signal (Lifetime decay) I am trying to deconvolve from a known impulse response function (IRF), as well as the IRF itself. I'm using scipy.signal.deconvolve. Please note for ...
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### Rectified Distribution

I have a vibration signal data with 2500 data points. I want to make a rectified distribution from this signal as appear in figure 4 here to calculate the rectified skewness of the signal. From ...
77 views

### How to calculate the envelope of a complex signal using python [closed]

I used the scipy hilbert function to calculate the envelope of my signal. The problem is that the signal is complex, so it throws an error when I use Hilbert function. I tried to just use the real ...
78 views

### Are scipy second-order Gaussian derivatives correct?

For an edge detection algorithm, I need to compute second-order derivatives of an image, and I do this with use of Gaussian derivatives. I assumed that the ...
38 views

### scipy.signal.stft temporal resolution

Using the STFT function from scipy.signal has produced unexpected results for me. I am performing an STFT on 10 seconds of data, sampled at 25,000 Hz. I am using STFT settings of nperseg=256 and ...
55 views

### Can't seem to get welch function in scipy work correctly

I'm trying to learn DSP through using Python's scipy package. I have measure some 200Hz signal from a machine. Now I want to inspect the spectral density of the signal. Here's the signal plotted out: ...
63 views

### How to pad a array representing music to pad the stft of this array?

I have an array named samples of size (2, 1321967) representing an audio file. When I pass it to scipy stft with ...
92 views

### scipy.signal.spectrogram() - how to handle gaps in the timeseries data

Looking at the magnitude of variable stars - the dataset is from here: https://dogwood.physics.mcmaster.ca/Cepheid/URL/MW/BD-10d4669.html The magnitude plot: ...
36 views

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### scipy cross-correlation: interpretation

I want to compute the phase shift between two 1-D signals of same frequency, but before I'm trying to compute the time shift between. The cross-correlation function seems to be ideal for that but I'm ...
83 views

### Deconvolution with Python in real life

I have measured a signal which is convolved with the profile of the measuring apparatus. Now I want to remove this contribution to get the "real" signal. I am trying to do this with Python. ...
391 views

### Decimating Non-Uniform large time-series data

I'm working with accelerometer data that is sampled at a non-uniform rate. There are major gaps in the data. Below is a scatter plot of the data I can also give a sense of the frquencies at which ...
34 views

### narrow band filtering of a signal that is sampled at high frequency

I have a signal that is sampled at 2KHz. The frequency band of interest is from 1/60 Hz to 1 Hz, and I want the final signal to be downsampled to 10 Hz. What is the best way to do this? I read that ...
30 views

### Getting error while performing upsampling of an audio signal processing using low pass filter in python

I want to perform upsampling of an audio signal introducing zeros between samples to create a longer signal with factor of N=2. The sampling rate is 44100Hz, time = 5sec. ...
58 views

### Why use both a high pass and a low pass filter in a Butterworth implementation for noise reduction?

I am a new to audio processing . I want to develop an application that reduces audio noise using a Butterworth filter. I found some existing code doing this, but I still do not understand the use of ...
107 views

### Invertible low-pass (Butterworth) filter in python (scipy)?

Question Is there an invertible low-pass filter built into scipy.signal (or other python package)? If so, what is it? If not, why not (is there something ...
65 views

### How to calculate PSD if i have power vs freq spectrum?

i have a signal something like this how to calculate PSD? i have freq from 191000200 to 196500000 time gap or delta t = 1 or 2 sec, (what i mean is [tn] - [tn-1]) i will be computing in python any ...
661 views

### Difference between librosa.stft and scipy.signal.stft

I read the source code of librosa.stft and sicpy.signal.stft, and notice that the calculation results of STFT(short-time fourier transform) in these two libraries are quite different: In scipy.signal....
55 views

### Apply FFT to positive spiky signal

I have a signal that looks like this It has regularly occurring peaks 50 units apart, and offset from 0 by approximately 20. I thought I could apply the DTFT to this signal and extract the period (...
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### Compare two Fourier transforms of two signals by calculating the coherence

My overall aim is to compare the edges of two images by comparing their Fourier Transforms (FFT) and to calculate one number as a key performance indicator that describes how much they are similar to ...
33 views

### Problem wih (diverging?) digital IIR filter for an online acquisition system

I am trying to plot windows of acquired data from an LSL-compatible system. For the example below, let's consider 1-second window of a 64 channel EEG system. In practice, I use shorter 0.2-window, but ...
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### How to correctly set the zi parameter (initial condition) for a scipy IIR filter

Let's take as an example an IIR filter using the 'sos' output, as this is what I use the most. To apply a bandpass filter, you can do: ...
66 views

### Difference between MATLAB zp2sos and python zpk2sos functions

I am trying to port some code from MATLAB to python. The goal is to use Butterworth filter (4th order, bandpass) API and convert it to second-order sections. I get the same output between MATLAB and ...
53 views

### Obtaining real numbers from FFT with same length as original signal

In this article the real valued time domain signal is transformed to the frequency domain to extract some features like mean or variance. But after transform to the frequency domain I calculate ...
73 views

### Trying to implement matlab pwelch function in python using scipy welch

I am trying to port the statistics toolbox function pwelch from matlab into python, but when I am trying to implement it using scipy.signals.welch, it does not return the same results as it does in ...
122 views

### How do I set window length and shift length for computing STFT on Scipy?

Does nperseg=32, noverlap=16 mean the window length is 32mS with a shift of 16mS? Refer here for more details
29 views

### Periodogram/PSD from FFT amplitude

I have performed a STFT for signals and obtained the amplitude through ...
143 views

### Boundary effects with scipy.fftconvolve after convolution

I am having some numerical error in my code that propagates continuously, and has to do with the implementation of convolutions in Python; this is kind of struggling my progress and I would really ...
20 views

### Using Scipy.correlate2d output matrix to determine best image match

I'm struggling to wrap my head around how I can use the output of a correlation matrix to determine if my image is present. If I am trying to match characters, how can I compare the outputs of these ...
78 views

### trying to reproduce the behavior of initial conditions for the filter delays of scipy lfilter with R

I'm trying to reproduce the behavior of lfilter and lfilter_zi (from scipy) in R (using signal package if possible). This is the example provided by ...
447 views

### Scalograms in python

I am reading this paper to learning basic concepts of dsp and I want to reproduce the following scalogram of a test signal (fig 4.2 of the paper): It has been produced from the discretization of the ...
73 views

### Designing digital low pass filter with low pass-band group delay

I'm interested in specifying a digital low pass filter with low (and near constant) pass band group delay. I tried python's spicy.signal.minimum_phase to transform ...
150 views

### Memory efficient filtering with scipy.signal in Python

I have several EEG channels that need filtering, and one channel may reach a recording length of 12 hours or potentially even more. This results in billions of data points stored which, when loaded, ...
40 views

### Is there an a method to fit a wave created from two wave?

I need to get the frequency and amplitude for a wave that consists of multiple function. for example, if I have a sine curve (created from two sine waves), How can I extract the parameters for this ...
19 views

### What is the function of init in Active Contour Model

In practice of image processing using scikit-image, I didn't understand the role of constructing init numpy array in Active Contour Model example. Is it the red section drawn in the example astronaut ...
500 views

### How to apply an anti-aliasing filter before downsampling

I have an eeg signal with two channels (f3m2 and f4m1) which is divided into epochs. I want to augment the data by taking every 5th sample. I can re-use the discarded samples to create 5 versions of ...
120 views

### Find corresponding wavenumber from FFT - Python

I have a set of data taken from a high speed camera. I've done some image processing which results in getting a pixel location at each frame. This oscillates with time and so I have performed an FFT ...
129 views

### Compute minimum phase version of a FIR

I am working with HRIR filters, in particular I am trying to interpolate them. One commod method in the literature to perform interpolation of HRIR is to use the minimum-phase decomposition and ...
80 views

### refractive index KK relation

I make Kramers Kroing relation(KK relation) with scipy.integrate.quad to change $\kappa(w)$ into $n(w)$. Their KK relation is \$n(w) = 1 + \frac{1}{\pi}\int_{-\infty}^{\infty} \frac{\kappa(w^{\prime})}...
46 views

### Interpreting scipy spectrum from audio signal

I have recorded some audio and would like to obtain a spectrum from it. As the audio is a real valued signal, I figure that I could perform a FFT with some window and obtain a spectrum for that period....
1k views

### What Are The Semantics Of Wav-File Sample Values?

The title is the question. To make this concrete, assume I have a standard 16-bit single channel wav file, with (although it doesn't matter) a 16000 Hz sampling rate. Each sample magnitude will be a ...
71 views

### Why is FFT-based convolution efficient only for signals of large size?

According to the documentation of scipy.signal.fftconvolve This is generally much faster than convolve for large arrays (n > ~500), but can be slower when only ...
103 views

### The difference between tensorflow stft and scipy stft

I'm trying to wrap my head around stft, and checking the docs, tf.signal.stft and ...
44 views

### Filter design for an unusual EEG experiment

I'm designing a quite unusual (in terms of signal analysis) EEG experiment, which forces me to design my own filter. I have never done this before, so kindly please check my work and suggest ...