Questions tagged [scipy]
The scipy tag has no usage guidance.
43
questions with no upvoted or accepted answers
3
votes
0
answers
52
views
Are there any tools for generating fixed point filter implementations?
It's very easy to make a filter in Scipy or many other tools, but implementing this filter in fixed point in C or VHDL/Verilog is always a chore. I mean, in theory it's just a matter of adequately ...
- 248
3
votes
0
answers
9k
views
Downsampling and upsampling of a signal in Python
If I want to downsample a signal in Python, is it better to use method resample from SciPy Signal Processing module or method decimate from the same module? What is the difference between these two ...
- 31
2
votes
0
answers
156
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(...
- 171
2
votes
0
answers
441
views
Filtering a square signal with a median filtering to preserve the edges
If needed, you can find my first post for this problem here.
I am trying to clean the following signal:
As proposed in the comment, I tried to use this post proposing 2 methods: median filtering and ...
- 191
2
votes
0
answers
1k
views
real refractive index from Kramers Kronig relation
I have a measurement of the complex part of the refractive index $k$ (where the refractive index is $m = n + i\,k$) measured at a nonlinear grid of wavelengths or frequencies that span several orders ...
- 123
2
votes
0
answers
207
views
Alternative to scipy maximum_filter to find peaks?
I'm using scipy maximum_filter together with binary_erosion to find peaks in my spectrum.
I just wondering if there are any ...
- 121
1
vote
0
answers
39
views
STFT normalization
In Scipy's implementation of STFT, an argument allows to scale the result as a spectrum or as a psd :
...
- 51
1
vote
0
answers
38
views
1
vote
0
answers
95
views
Prony method doesn't work
I have used the code from: https://github.com/quantumlib/OpenFermion/blob/v1.5.1/src/openfermion/linalg/wave_fitting.py#L41-L76
try using with my signal:
...
- 123
1
vote
0
answers
524
views
Spectrogram of x,y,z data from accelerometer
Using scipy.signal.spectrogram for creating spectrogram and matplotlib's pcolormesh for plotting.
I'm working on a project where I'm using a spectrogram to visualize the frequencies of the ...
- 11
1
vote
0
answers
151
views
1
vote
0
answers
498
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 ...
- 121
1
vote
0
answers
163
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....
- 111
1
vote
0
answers
237
views
Is there a way to get output in second order sections (SOS) format from Scipy's signal.firwin
I am using Scipy's signal.firwin to implement a lowpass filter. Using the rule of thumb formula(s) to estimate the order of the filter, I am getting a very high number. I looked into this question, ...
- 69
1
vote
0
answers
190
views
Why are low frequency peaks not sharp in scipy fft?
I am using numpy/scipy to plot graphs of sine waves. frequencies at 15 Hz or higher give nice, sharp peaks, but at lower frequencies, the peaks are smeared and the actual peak frequency can't be seen ...
- 11
1
vote
0
answers
358
views
Understanding why spectral flatness cannot be computed
I have a real signal recorded 512Hz for 1s. After resampling the signal at 256Hz, I would like to compute its spectral flatness. To do so, I start by taking its discrete Fourier transform with ...
- 49
1
vote
0
answers
3k
views
How to design an interpolated notch filter in Python to filter powerline harmonics
I have a a time domain data set that records the magnetic field vs time, which must be processed to reveal an embedded signal. This data also contains power line harmonics (i.e. multiples of 60 Hz) ...
- 111
1
vote
1
answer
711
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
- 11
0
votes
1
answer
72
views
Numerical issues in scipy's Savitzky Golay filter coefficients for large polynomial order
Consider the design of a Savitzky-Golay filter of window length 101 and (high) polynomial order 20. Using scipy version 1.10.1, the filter coefficients can be obtained in python as:
...
- 375
0
votes
0
answers
92
views
Initial conditions of backward filter for forward-backward filtering on chunked real data in python
I have to apply a downsampling filter on a realtime data stream (signal) and I want to do it in python. The data is sampled at 16 kHz and loaded in a loop in chunks of 1 second. I have to downsample ...
- 31
0
votes
0
answers
15
views
Extract PVC feature from singal to train the ML model with PVC characteristics
I have ML model which is trained on Afib, Normal, Other - 3 class. Currently when I am testing the model with unseen database, sometimes it identify PVC singals as Afib class.
For example -
enter ...
0
votes
0
answers
308
views
Jerk detection in accelerometer data
I want to detect jerk from accelerator data i.e. values beyond 1.57 m/s^2, but due to the high frequency nature of the sensor (400 values per second), it gives multiple jerks instead of one.
How can I ...
- 11
0
votes
0
answers
83
views
Decimate a signal whose values are calculated, not stored
tl;dr I'm looking for something like Scipy's decimate function, but one that takes in a generator, rather than a Numpy array.
I am turning on and off a light using ...
- 101
0
votes
0
answers
130
views
Understanding FFT bins interpretability
I am familiar with the continuous Fourier transform yet the more I try to understand FFT, the more I'm confused. If we've got a discrete N sample signal, FFT is a faster way to calculate DFT. If ...
- 1
0
votes
0
answers
19
views
Creating 60s strips from ecg signal recording ( .bat ) file and give it a label as per the datapoint present in it
I am working with https://physionet.org/content/mitdb/1.0.0/ dataset where we have 48 ecg signal files.
Each recording is 30 minutes long and I Want to create 60s strips and give it a label. ie based ...
- 131
0
votes
0
answers
71
views
Issues on EEG PSD feature extraction using signal.welch
I am new to EEG signal processing and I am having some issues on calculating PSD using scipy.signal.welch. I am trying to implement a function to extract PSD features. The input of this function is a ...
- 1
0
votes
0
answers
135
views
How to design function for Random Decrement technique in python and implement the function?
I was looking into a technique called Random decrement technique from the following links/articles:
How can I use Random Decrement Method to convert a non-stationary
signal into a decay function ...
- 145
0
votes
0
answers
908
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 ...
0
votes
0
answers
168
views
Periodogram/PSD from FFT amplitude
I have performed a STFT for signals and obtained the amplitude through
...
- 29
0
votes
0
answers
833
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 ...
- 141
0
votes
0
answers
159
views
Why is there a difference in the spectrum of an audio file between Sonic Visualizer and my Python script?
I am working on a script which is creating a spectrum analysis from an audio file using SciPy and NumPy. Before I started, I analyzed the file using Sonic Visualizer, which got me the following result:...
- 101
0
votes
0
answers
108
views
Lowpass Butterworth filter equation
I am using a 5th order lowpass Butterworth filter with a varying cutoff frequency, $f_c$, to smoothen some data coming from a spectrometer. An example of a spectrum, plotted with the filtered data, ...
- 1
0
votes
0
answers
169
views
Negative Exponential Filter SciPy
I'm trying to transform a time series with a recursive filter to model a feedback.
I was able to do a simple filter like :
...
0
votes
0
answers
152
views
Scipy Deconvolve help
I was playing with the deconvolve method in scipy and I can't seem to get it working properly (I am still really new to DSP/deconvolution). I convolved a gaussian with a fwhm of 2.0e-9 with a ...
0
votes
0
answers
566
views
Filtering out different narrow-band frequencies at once
I have asked a closely related question on SO at https://stackoverflow.com/questions/55168460/python-implementation-for-filtering-out-multiple-distinct-narrow-band-frequencie
but I am still unclear ...
- 141
0
votes
0
answers
88
views
Scipy Welch's gives different first element
I've re-implemented Welch's method and want to compare it to scipy.signal.welch. However, the first two and last elements of the resulting array are different.
My ...
- 101
0
votes
0
answers
158
views
How to know the time of my window to calculate the STFT with python knowing only the length?
I am trying to implement a work presented in an IEEE paper where they have mentioned that the STFT was performed on the signal measurements to obtain a spectrogram with no overlap window of 3 min :
I ...
- 1
0
votes
0
answers
213
views
how to detrend a carrier phase with butterworth filter?
I am new with detrending techniques, I have a carrier phase measurements and I want to detrend it by 6th order butterworth digital filter. After creating the digital filter I get its numerator (...
- 113
0
votes
0
answers
351
views
Translating Bessel filter from python to C - odd behavior past the cutoff frequency
I recently translated the code from scipy.signal.bessel to C in order to implement a bessel filter in a piece of analysis ...
- 320
0
votes
1
answer
267
views
spectrogram of a (strongly) downsampled file
I downsampled an audio file to a very low sampling rate, 48hz.
This is because I stored some information in the file, that are not really audio information but the audio format was convenient to use.
...
- 23
-1
votes
1
answer
1k
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 ...
- 11
-1
votes
1
answer
277
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 ...
-1
votes
1
answer
106
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 ...
- 1