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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.

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15 views

Spatial smoothing - 2D MUSIC [FMCW MIMO radar processing]

I'm using a 2D Music algorithm for the estimation of Range-Azimuth info in a ULA FMCW MIMO radar. The algorithm procedure is pretty simple as per Belfiori F., Application of 2D MUSIC Algorithm to ...
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1answer
37 views

Fast Recursive 1D Signal Smoothing - IIR / Auto Regressive Implementation of Gaussian Smoothing

I have just begun to dive into the field of signal processing, but there is the need to program a digital filter, that has to smooth a realtime signal from a sensor device. As far as I know, in my ...
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0answers
19 views

Modified Bryson-Frazier (MBF) smoother explain

I'm reading about MBF smoother on Wikipedia. I'm confused of the quantity $\hat{\lambda}_k$ and $\tilde{\lambda}_k$. What does they really mean intuitively ? Why the update formula has the form $\...
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1answer
77 views

Chromatogram peak detection - bunching vs others?

Reading presentations from existing tool providers I noticed that in order to detect peaks they first use bunching (average N points) and then use slope and curvature to detect peaks. I'm guessing ...
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0answers
30 views

Are there any applications using absolute Savitzky-Golay filter to smooth data and preserve non-negative properties?

I want to smooth peaks for non-negative matrix factorization (NMF). Since Savitzky-Golay has polynomial smoothing, I think it is good for narrow peak shape in my signal profile. But NMF needs to be ...
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2answers
999 views

Why should an image be blurred using a Gaussian Kernel before downsampling?

I recently read that before downsampling an image, it should be blurred using a Gaussian Kernel. This way, the downsampled image is better than just picking a single pixel out of a NxN block or ...
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3answers
531 views

Savitzky–Golay filter vs. IIR or FIR linear filter

A traditional IIR / FIR filter (lowpass to remove the high freq oscillations), e.g. moving average, or a Savitzky-Golay filter can all be useful to smoothen a signal, such as an envelope signal: ...
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1answer
84 views

What Are Different Approaches to Realize a Gaussian Blur (Smoothing) Step on an Image? [closed]

Could some review some methods to apply Gaussian Filter (Blur) on an image besides the direct one using Truncated FIR (classic convolution with Truncated Kernel) approximation?
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0answers
26 views

EKF smoothing for prediction at t=0 when no there is no measurement

I have a simple first-order reaction batch system for which I have some discrete measurements ($0<t_{k}\le t_{endbatchsample}$). I have an initial guess for $x_0$ and $P_0$ and from here I ...
3
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1answer
186 views

Does this Signal Smoothing algorithm have a name?

We are reverse engineering some 20 year old software. Original developers were laid off years ago, and cannot be found. In this code, there is a signal that is getting smoothed as follows: $P_{new} ...
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0answers
55 views

temporal smoothing and signal distortion

I compare two signals (blue and red). Each signal is an average of many observations (shades are standard error of mean). I need to show that the the blue signal is significantly above red one at the ...
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4answers
270 views

Make a signal that fits another the best possible with a limitation in the 2nd derivative

Consider this step function: The signal that "fits" this should look like the following (in green): The corners are now smooth because the maximum second derivative allowed is not infinite anymore. ...
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1answer
70 views

How to smoothen signal with missing values before differentiation?

I want to differentiate a noisy signal with many, randomly located, missing data values. Which smoothing techniques should be applied before differentiating the signal? I have a velocity signal at ...
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1answer
213 views

How to smooth (or interpolate) phase of FFT and reduce data points

I am writing some code for audio analysis, and have currently got two signals with FFT performed on them. I get the phase of my complex array by using: ...
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0answers
132 views

Estimate standard deviation of random-walk using Kalman filter

I'm new to Kalman filters so this might be a stupid question. I created a Kalman filter that takes in time series observations and estimates the mean of that time series. This is simply modeling a ...
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2answers
340 views

How to Mesure the smoothness of a signal

so how can i determine if a signal is smooth or not ? And if its possible to get something indicating the level of the smoothness of my signal. I looked at the r-squared and hurst exponent but i ...
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0answers
49 views

Is the higher order spline interpolation better than the cubic spline interpolation? [duplicate]

i am so confused with the accuracy of the spline interpolation. if higher order spline is better, then please do mention the examples. thank you!
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1answer
42 views

Should zero element be considered to calculate mean when smoothing spectrogram by window?

My (mass spectrometry) spectrogram does not measure the intensity constantly. I obtain the spectrogram, for example, ...
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0answers
26 views

Smooth data of Biozimpedance

I'm dealing with data of Biozimpedance to extract the respiration rate and trying to smooth it before further processing. The simpest way I used is a moving average. The problem I'm having is that ...
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2answers
80 views

What is limit on performance of edge-preserving filters for low signal-to-noise regimes?

Let's say I have a signal, $x(t)$, defined as such, $ x(t) = \begin{cases} 0 &\text{if} \,\,\, t < -\alpha/2 \\ \frac 1\alpha t+\frac12 &\text{if} \,\,\, -\alpha/2 \leq t \leq \alpha/2 \...
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2answers
648 views

Find smoothed first derivative from signal with noisy slope

How can I get filtered first derivative from a noisy signal that has slowly changing slope in form of y=kx+b? k can slowly ...
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1answer
209 views

Smoothing or bigger FFT bins?

I have an FFT of a radio signal, to look at "what's happening" in the frequency domain. I'm interested in signals that are "wide enough", eg 1MHz, and thus would like to smooth the result to filter ...
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1answer
43 views

Removing the Multiples of Decrease and Increase in a Spike

I have a signal shown below. I got this signal from a glove, where I want to detect the movement of a finger. What I am planning to do is to threshold the signal, so I can get a binary signal ...
2
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1answer
193 views

smooth noisy irregularly spaced data containing peaks

I've got a set of scans of an object (human body) from different angles, which are being combined to reconstruct a 2D-representation. The raw measurements (blue plot below) contain a fair amount of ...
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2answers
348 views

Effect of Gaussian Blur on Different Frequency Components of an Image

Gaussian blur is lowpass filter which means it pass the low frequency components and stop the high frequency component but the point I am not getting is that if it is lowpass filter then how it is ...
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2answers
1k views

Estimating the standard deviation of Gaussian filter from smoothed image

Firstly, let's say that in order to smooth an image, I convolve it with a Gaussian function having standard deviation $\sigma_x$ and $\sigma_y$. I am now interested in knowing if there exist methods ...
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0answers
150 views

Triangle smoothing

How can I make a triangle smoothing matrix? I have tried Toeplitz matrix but I need it to be symmetric and invertible. I want to apply it to my data by matrix multiple. I tried this: ...
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5answers
6k views

Is there a technical term for this simple method of smoothing out a signal?

Firstly, I am new to DSP and have no real education in it, but I am developing an audio visualization program and I am representing an FFT array as vertical bars as in a typical frequency spectrum ...
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1answer
999 views

Generating smoothed versions of square wave, triangular, etc

I'm trying to get functions depicting smoothed out versions of wave forms(triangle,square, sawtooth, reverse sawtooth) which have the same amplitude and frequency as $cos(x)$. I found a few ...
2
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0answers
310 views

Fast implementation of LOESS for equally spaced samples (possibly using convolution)

Is it possible to do LOESS smoothing on equally spaced data using convolution? The Wikipedia article on LOESS mentions a possibility of using a FIR filter for LOESS. I could not find anything more ...
5
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1answer
923 views

How does this “simple filter” work?

I'm new to DSP, and I'm using this basic "1-pole LPF" Param Smooth filter which "smooth" param when I change it. The code is pretty simple: ...
2
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2answers
751 views

Smoothing a staircase

I have some data from a position encoder, so naturally i want to estimate its speed. However, the data is very quantized, so it's difficult to smooth enough to differentiate easily: Each step level ...
3
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1answer
806 views

Smoothing a power spectrum

My question is regarding how one could/should smooth a rather noisy power spectrum obtained from measurements. There are various methods one can use (a moving average, binning, etc) and I am not sure ...
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2answers
846 views

The difference of downsampling an image and smoothing an image?

I am, at the moment, trying to read up on some simple computer vision elements, in which i have become a bit comfused on the terms downsampling and smoothing, and whether there is a difference between ...
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1answer
170 views

midpoint smoothing spline

Suppose we have a time series which have peaks and troughs.(The red curve below) I would like to get an algorithm which is able to identify the peaks and troughs locations, then find the midpoint ...
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1answer
82 views

Is there a name for this smoothing formula?

Hi: I am reading a book called "lectures on wiener and kalman filtering" by Professor Thomas Kailath. On page 18, it says the following: To carry through this approach, let us first note that a ...
3
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1answer
1k views

Gaussian Pyramid - How is Subsampling Rate Related to Sigma?

I found a gaussian pyramid implementation in a MOPS paper (feature detection). They use sampling rate $s=2$ and $\sigma=1$ - i.e. to generate a new level of the pyramid, the current level is smoothed ...
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2answers
95 views

What criteria should be used for smoothing

Actually I have some measurement which I want to get rid of noise I want to use different filter techniques but I am wondering what criteria I should use to check if I am removing noise or not or if ...
3
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2answers
3k views

detect to rising, stable and falling point in non-smooth rectangular wave

I am working on basic signal processing problems in MATLAB. I have found a signal from the internet (i don't remember the site exactly). The data is organized in column wise. 1st and 2nd column is ...
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0answers
87 views

Why does increased kernel bandwidth equate to increased SNR values?

If I apply a Gaussian Kernel to an image with some noise applied to it and I want to remove that noise, why does the Signal to Noise Ratio increase as I apply kernel's with higher and higher sigma ...
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2answers
528 views

Structuring Kalman filter for tracking problem where only position is known

I'm new to Kalman filters and my extensive web search about them has helped me understand the majority of it (or so I think). However I still need some light shed on my problem formulation. I have a ...
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0answers
39 views

Proximal operator of image Laplacian

Let $\alpha, \beta > 0$ and $\Delta := \nabla^T \nabla$ be the discrete laplacian operator, $$\nabla: \mathbb{R}^{n_x \times n_y \times n_z} \rightarrow \mathbb{R}^{3 \times n_x \times n_y \times ...
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1answer
520 views

Implementing a 1-D Kalman Filter Regression, Missing the smoothing action (getting the opposite)

I am implementing the 1D Kalman Filter in Python on a fundamentally noisy set of measurement data, and I should be observing a large amount of smoothing...but, instead, my Kalman Filter is doing the ...
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1answer
278 views

Get phase information from bursty time series with amplitude variability and sharp edges

I have time series like this one, and I am trying to get the phase information from it. If it matters why, because I need to compute the precision of the cycles and amplitude variability is ...
4
votes
2answers
931 views

How do I smooth this noisy signal?

I have a numerical solution to a problem in mechanics. I am computing the force applied to an object as a function of its deformation and in the problem, there is an instability, due to which the ...
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2answers
2k views

Compute the time derivative of a noisy digital signal?

The issue is that my signal is very noisy. I need extract its time derivative as accurate as possible. P.S. I do not have any prior knowledge on the signal (black box). On forums some suggested ...
2
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1answer
900 views

how to smooth estimated velocity

I have a manipulator that provides the position and the velocity of its end-effector. The velocity is noisy. I've implemented a filter in C++ to determine the derivative of the position. In the below ...
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1answer
70 views

What is the equivalent smoothing function to running the same Gaussian 8 times?

Suppose there is an image which is to be smoothed by convolving it with a Gaussian kernel with standard deviation $\sigma$. If the image is then smoothed with this kernel 8 consecutive times, is the ...
3
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1answer
269 views

Smoothing 3D Data for the Second Derivative

I am not a signal processing expert and my feeble attempts at solving this problem have come up short. I have a C++ application which is being fed regularly-spaced (in time) 3D position samples. The ...
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1answer
199 views

Cascaded one-pole sections and relationship to time constant

I have implemented a typical one-pole lowpass filter to smooth out some control signals. The form of the filter is: $$ y1 = x0 + b1\centerdot(y1 - x0) $$ x0 is the current input sample. y1 is the past ...