Questions tagged [smoothing]
Smoothing a signal or data set approximates the data to reveal patterns and exclude noise, fine-scale structure and rapid changing phenomina.
153
questions
5
votes
3
answers
665
views
Smooth envelope of an aperiodic signal
I have a signal that looks like this:
Red line is the function I'd like to obtain somehow. Everything <= -60 is basically absent data (i.e. not low signal).
If I understand correctly, Hilbert ...
- 163
2
votes
0
answers
29
views
Smoothing clicks when scrubbing/seeking through the audio
I have a buffer of N samples from which I'm playing a loop of L samples (L <= N) starting from sample S. The reading position is calculated as (S + P) % N where P is current playhead position which ...
0
votes
2
answers
77
views
1
vote
0
answers
60
views
Approximating fractional-octave Gaussian smoothing with non-causal variable-width IIR filters
I am trying to implement fractional-octave smoothing of amplitude response data with approximated Gaussian filters, as briefly discussed in this AES paper.
Unfortunately, no implementation details are ...
- 11
0
votes
0
answers
58
views
Which audio smoothing algorithm has the lowest latency?
I am working on an audio smoothing project. My inputs are from a record scratching MIDI controller, and I am trying to produce a smooth output (the raw data creates noisy audio).
I'm using a simple ...
1
vote
0
answers
52
views
Tap and Impulse Response of MATLAB Filter
This is a simplified version of the Savitzky-Golay MATLAB functions (sgolayfilt, sgolay).
...
- 175
5
votes
3
answers
103
views
The Effect of the Finite Radius of Gaussian Kernel
Page 168 of Digital Image Processing, Global Edition says:
we know that the values of a Gaussian function at a
distance larger than 3𝜎 from the mean are small enough that they can be ignored.
If we ...
- 249
4
votes
1
answer
107
views
The Effect of the Order of Downsampling and Smoothing on the Output
How do I prove or disprove:
Smoothing an image with a 3x3 filter using full convolution and then downsampling an image by 2 produces the same result as downsampling an image by 2 and then applying ...
- 141
1
vote
0
answers
54
views
Fourier Derivative of Discrete Values in Python
I am attempting to find the time derivative of physical system measurements in the Fourier domain. The system can be modeled as an ODE and has a periodic solution.
$$\frac{d}{d t} y{\left(t \right)} = ...
- 11
2
votes
1
answer
104
views
Approaches to work around differing signal lengths when using Kalman filter
I have a set of vector valued signals $\boldsymbol{y}_{1:T}$ where each $\boldsymbol{y}_k \in \mathbb{R}^{v_k}$. Each signal is potentially of different dimensionality. I'd like to apply filtering and ...
- 23
1
vote
1
answer
161
views
low pass filtering for smoothing
I am using the following code in Matlab, from some source (sadly I cant remember).
The code is used for smoothing signals using a low pas filter.
...
- 13
1
vote
1
answer
281
views
Creating Triangle Filters for Smoothing using Python
The 'binning' process consists in summing the energies (squared magnitude) within groups of adjacent FFT values. This will give you the total energy in a set of disjoint frequency bands.
A more ...
- 77
0
votes
0
answers
105
views
Standard method of smoothing (amplitude envelope) of continuous wavelet transform
My basic question is, "What is the standard way to post-process/smooth a continuous wavelet transform result to measure the wavelet's activation at a specific frequency?"
When using wavelets ...
- 101
3
votes
2
answers
463
views
Applying a window to a signal
How can I Gaussian or Bartlett window to a signal? On the other hand, is it a good way of smoothing signals? If not what are the differences between smoothing and windowing?
2
votes
1
answer
222
views
What is the outcome of applying a derivative on X and Y for an image? and Other Gaussian Questions
I've been diving into smoothing kernels and I came up with a lot of questions that I haven't been able to find in the internet. If you can I'd appreciate the help :)
(Capitals and bold were used for ...
- 23
6
votes
2
answers
418
views
How to Deal with Outliers in Measurement of a Simple Model of Kalman Filter
I am trying to find the one-dimensional velocity of a car based on position measurements, similar to the Wikipedia article. The car moves at almost constant speed and I am mostly interested in ...
- 83
0
votes
0
answers
32
views
Signal filtering with physical limitations and estimated STD
I have a prediction mechanism that predicts some signal value. Generally the prediction look like this:
The are some ranges of systematic error and I cannot do anything with this. But in many points ...
- 1
0
votes
0
answers
252
views
Spectrum Smoothing
I recently stumbled upon this GNU Radio flow graph which smooths spectrum. Block parameters are seen in image attached below. Also visually results doesn't change if I take out "Keep 1 in N" ...
- 33
0
votes
0
answers
205
views
How to measure smoothness of a signal
Lets say I have two signals with a different number of data points - a step function and a smooth spline as you can see below. What is mathematical operation I can use to quantify the "smoothness&...
1
vote
1
answer
37
views
Constrained interpolation/smoothing of multi-dimensional time series
Consider an $N$ dimensional time series $x_i(t),~i\in\{0,1,\cdots, N-1\}$ where $x_i(t)$ is smooth. It turns out that for all $t$: $x_i(t)>x_{i-1}(t)$.
The multi-dimensional series is sampled at ...
- 375
0
votes
0
answers
91
views
Peak detection in noisy waveforms
I have a set of 1-dimensional time-series, a subset of which contain either one or two peaks, and the remainder of which are pure noise. I've smoothed these data by ...
- 123
0
votes
0
answers
86
views
Is there a technical term for smoothing or flattening the floor of an amplitude envelope?
I am working with the speech envelope, and I have been trying to make it act a little more like a bilevel signal by exaggerating the peaks and flattening out the floor.
I detrended and smoothed my ...
- 33
0
votes
0
answers
43
views
Is there any complex-valued function used to smooth signals?
To obtain a smoother signal, we usually convolve the original signal with a real-valued kernel function, such as Gaussian and Top-hat. Is there any complex-valued kernel function to smooth signals?
- 124
0
votes
1
answer
159
views
Calculate moving RMS with exponential averaging
This is moving RMS, now how to add exponential averaging in this
df['signal'].rolling(21*24*60).apply(lambda x: np.sqrt(x.mean()))
- 11
-1
votes
1
answer
38
views
Data smoothing in temperature measurements from MLX90614 BCC IR sensor
I am trying to measure temperature with the MLX90614 BCC IR sensor for my project, and I am having problems with my precision requirement. I had taken data for 1 second then took the mean of these ...
- 1
0
votes
0
answers
412
views
Choose the right Sigma for Gaussian filter
I have the following problem: I have a time series with counted data. I now want to smooth it using a Gaussian low-pass filter. Is there a method to determine the sigma value? The window should have a ...
- 1
0
votes
0
answers
95
views
Box function signal filtering in python
I am trying to produce a box function filter of a signal in python. I expected to find this functionality in scipy.signal, but I can't find any solutions. What I am trying to do is this.
I have 2 ...
- 115
0
votes
1
answer
526
views
Smoothing power spectrum by convolution with boxcar function
I am trying to smoothing a signal's power spectrum by convolving the spectrum with a boxcar function in frequency domain. However, the result is obviously not what I expected: original two frequency ...
- 155
0
votes
0
answers
39
views
Smoothing peak spectra in time domain
I would like to smooth amplitude spectra of signals around their peak frequencies. I could perform FFT, find the peak frequency, and smooth around the peak in frequency domain, then inverse FFT back ...
- 155
4
votes
1
answer
426
views
Deriving a Kalman Filter Equation for a Linear Gaussian Filtering Model with Non Zero Mean Noise
I am trying to answer an exercise question from the book Simo Sarkka - Bayesian Filtering and Smoothing.
The question is:
Does anyone know if there is a resource that has the solutions for this book?
- 41
3
votes
1
answer
3k
views
The Effect of the Standard Deviation ($ \sigma $) of a Gaussian Kernel when Smoothing a Gradients Image
I am trying to understand why smoothing an image with a gaussian kernel of different sigma values and then computing the gradients of the smoothed image leads to "thicker" trails. In the ...
- 283
1
vote
1
answer
1k
views
What is the point of smoothing an FFT or spectral density plot, and how does that affect the noise floor?
It appears that smoothing the FFT or spectral density plots of a noisy signal is a common practice. I see that common tools like MATLAB and Python have functions built in to their FFT tools to do just ...
- 81
0
votes
1
answer
185
views
Is it applicable to implement a cascaded moving average filter with variable window on real-time?
I am using a 3-pass cascaded moving average filter for smoothing noisy data. I applied some optimization algorithms to determine the optimal length of the MAF window.
For different amplitudes of data ...
0
votes
1
answer
88
views
Error introduced by smoothing filter at the end of a processing block
I'm running analysis on a multichannel audio signal and due to the size have decided to process it in blocks (my computer doesn't have enough memory to process it in one go). Some of the data produced ...
- 27
6
votes
1
answer
275
views
A Simple Algorithm to Filter / Smooth / Denoise a Noisy Staircase Graph
Is there a way to remove the noise and smooth the graph into a staircase graph.
- 63
0
votes
1
answer
192
views
Possible to get transfer function coefficients from window?
I am hoping to use scipy.signals.filtfilt() to smooth some signals in Python, and wanted to build the filter based on a window like a hanning window or whatever. E....
- 103
5
votes
3
answers
135
views
Reversing the Order of Operators for Edge Detection?
Usually, for edge detection, we perform smoothing and then pass it through difference filter. What if application of difference filter happens first and then smoothing. How the math behind the same ...
- 53
0
votes
1
answer
25
views
I want to get tilt sensor value for a given time t_0, but the tilt sensor data points are discrete. How do I interpolate between the discrete points?
I have 3-dimensional readings from a tilt sensor (specifically these are rotational angles about X, Y, and Z axes) over time. Let's call these angles S. I want to infer S at a specific time t_0, but ...
- 103
1
vote
2
answers
949
views
How to properly smooth the phase of a spectrum (or any unit-complex function)
I want to smooth the phase of a measured (transfer) spectrum without destroying unit-complexity of the phase factor. Suppose
$$f:\mathbb{R}\to \mathbb{C}\qquad , \qquad f(\omega)=r(\omega)\cdot {\rm e}...
- 256
-1
votes
1
answer
664
views
Smooth signal with Hanning
I have an acceleration record and i want to smooth it's spectrum by using a hanning window with Bandwidth=0.5 Hz.
How could i do that?
Example in python/matlab will be appreciated!
- 11
1
vote
2
answers
648
views
Confused in Smoothing a signal in the Frequency domain
First of all i am new in DSP, so i have no solid education in the field.
I have convert my time domain acceleration-seismic data to frequency using DFT and i am trying to smooth the DFT data, in ...
- 11
0
votes
3
answers
580
views
How do you do signal averaging on a realtime data?
Smoothing algorithms implemented by me
Exponential smoothing - https://www.openprocessing.org/sketch/771368
Moving Mean - https://www.openprocessing.org/sketch/540696
For example - a1+a2+a3+a4+... ...
- 101
1
vote
2
answers
127
views
Smoothing a discrete function with point wise variances
In Stark's Introduction to numerical methods [1970] it suggests fitting local polynomials to smooth discrete data before the Fourier transform using least squares minimisation. This gives the ...
- 111
0
votes
1
answer
71
views
Can you predict how long a discontinuity will take to reach its target if it is low pass filtered at a certain frequency?
Let's say you have a signal that relatively slowly rises from 0 to 1, then suddenly from one sample to the next drops back to 0, creating a sharp discontinuity. Let's say you run it through a one pole ...
- 447
0
votes
2
answers
631
views
Filterpy Kalman Filter batch processing with multiple measurement sources
In pythons module for kalman-filtering, filterpy, there is a function batch_filter() to batch filter a list of measurements that then can be used for RTS-smoothing. ...
- 101
4
votes
2
answers
1k
views
Kalman Filter EM Estimation of Covariances
The question might be very simple, but I get a strange result from Kalman Filter. Let us consider the simplest state-space model, the random walk plus noise:
$$
y_{t} = x_{t} + \varepsilon_{t}\\
x_{t} ...
- 171
0
votes
0
answers
65
views
Slew Rate Filter With Different Smoothing Factors in Each Direction
I'm smoothing the output of an ADC with a simple first order low pass filter. Of course the smoothing rate is the same whether the signal is rising or falling.
Preferably the smoothing rate needs to ...
3
votes
0
answers
239
views
Algorithm for smoothing the output of an object detector operating on a video?
Please could you point me towards an algorithm that takes a series of object detections performed on a frame by frame basis as input and outputs a filtered series of object detections in which the ...
- 173
0
votes
1
answer
148
views
Selected bin oscilation in STFT
I am looking for a noisy signal using STFT. My window length is 128 and I am using 75% overlap. I am using a Hanning window before running the FFT process. I am using Quinn's 2nd estimator for ...
- 199
0
votes
0
answers
203
views
temporal smoothing: FWHM of Gaussian kernel vs. window length of moving average
Suppose in one case I convolve Gaussian kernel with FWHM=10 samples. I would like to compare the result with moving average. My question: should I take the moving average window also 10 samples? In ...
- 101