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Questions tagged [algorithms]

Algorithm is a method expressed in a finite list of steps of well-defined instructions to process a signal.

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37 views

Is there an intensity estimation algorithm working solely in time domain

Given a second of sampled sound pressure signal, speed of sound and medium density, can the average sound intensity be estimated without performing DFT, that is in linear time by simply traversing all ...
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22 views

Determine 3 most dominant frequencies in a signal, PSD or just the absolute value of a Fourier transform?

I have a noisy ECG signal recorded for 5 minutes. My goal is to determine heart rate every 2 seconds. To find out 3 most dominant heart rates (Beats per minute) in a 2s-signal should I calculate its ...
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30 views

Are there existing algorithms to detect reverb in a voice recording?

I want to be able to detect if a spoken voice recording happened in a room with a lot of reverb or not. I don't need to be able to extract the exact reverb profile of the room. Ideally the algorithm I ...
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13 views

If signal is gaussian and noise is uniform, how to update NMF with 2 different prior distributions?

I am doing supervised NMF (non-negative matrix factorization). $V$ is the mixture of signal and noise, the learned features are supervised as $W_{s}$, $W_{n}$. $$V \approx [W_{s} \ \ \ W_{n}] \times ...
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21 views

Approach for finding same color area border line

I have never studied image processing algorithms but I need to create an overlay layer for a map, starting from some data observed in precise points for which I have the geographic position. I want ...
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32 views

Ways to parallelize Sifting in EMD (Empirical Mode Decomposition)

Sifting process, which is recursive in nature, is used in EMD (Empirical Mode Decomposition) to decompose the signal (x(t)) into Intrinsic Mode Functions (IMFs) and residue, which is a monotonic ...
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19 views

Improve NMF for data with partial overlaps in multiple groups?

I want to use NMF to separate true sources from data. My data is in group structure with overlap elements. For example (in the smaller version) group1: contains A,B,C,D,E,F,G patterns group2: ...
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16 views

Message-round probability in SCCC graph

I am reading the paper Interleaver Design for Serial Concatenated Convolutional Codes by Yu et al., and it states the concept of message-round probability as $F(l_1)F(l_2)$ where $F(l)$ refers to the ...
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26 views

Fast morphological erosion/dilation with variable window sizes

I want to perform the following operation on an image: consider a square window around every pixel, find the maximum value in this window, and replace the central pixel value with this maximum value. ...
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58 views

Frequency detection in audio and what parameter or set of parameters help/limit frequency detection

I'm trying to learn audio and voice/speech processing techniques out of interest. I intend to learn, experiment with algorithms and design, implementation of such systems, frameworks using programming ...
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18 views

Compare images of road marker

I just want to check my approaches to the problem and see if they are really correct or whether there can be a better way Problem: I have a scene of road marker (they are predominately lane lines, ...
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43 views

How can I evaluate the complexity of two solutions when both additions and multiplications are present?

I am evaluating FFTs algorithms radix-2/4 and split radix. (although this talk can be applied to any algorithm). Each of them has a certain amount of complex additions and multiplications. That can ...
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78 views

Perspective Transform using depth and scale information

I want to transform perspective on an input image and output image from the new perspective. I have depth map and scale information. The picture roughly demonstrates what I want to do. I have a single ...
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3answers
94 views

Efficient calculation of exact frequency from a broad frequency range (1 Hz - 1000 Hz)

I have some input signal sampled at 1-10 MS/s. Let's assume that it contains one strong frequency component (with frequency anywhere in the range from 1 Hz to 1000 Hz or even higher, changing over ...
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31 views

Output of a bank of gabor filters, derive ellipses like regions

I'm trying to implement an algorithm that show how to detect wrinkles in clothes, without going to much into details this is the step that is confusing me. Assuming we have an image $I$ and a set of ...
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490 views

GNU Radio polyphase clock sync block: how do I use it?

I'm trying to receive some simple PSK real world signal with a sdr and GNU Radio The problem I currently face is « how do I use the polyphase clock sync block ». I read https://wiki.gnuradio.org/...
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115 views

Do you recognize this filter?

I'm trying to decipher the uncommented source code of SoundBox which is a little music tracker written in javascript. There is an included synthesizer, which applies a filter on the output samples. I'...
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66 views

High/Low Pass Filters from Zero

I everyone, I'm a computer scientist but not from the signal processing community. I want to implement a real time digital low pass filter (to begin with) for a sound processing application. I've ...
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16 views

Simple question about HS algorithm's formul(Optical flow)

In the below pic, I can not understand what U vector is? It says flow field but I can not imagie what really is the flow field?
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1answer
37 views

FFT for distance-limited sum of pairwise products

I have a sequence of fixed length $N$ input arrays ($x_0$, $x_1$, ..., $x_{n-1}$), and my goal is to compute output arrays as such: $$d_{00}[l] = \sum_{i = 0}^{N - l} x_0[i]x_0[i + l]$$ $$d_{01}[l] = ...
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57 views

A question about visualizing “Lucas-Kanade(optical flow)” algorithm

I am reading O'Reilly's OpenCV 3 book. In keypoints section(for tracking objects), there is an algorithm named "Lucas-Kanade". in the below image it tries to give a visualization of it but I can not ...
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331 views

Using the Kalman filter given acceleration to estimate position and velocity

Note : port from this post, until fully merged. I am reading data from an accelerometer. I want to use this data to estimate velocity and position. Originally, I performed a double integration of ...
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23 views

Optimization algorithm for look up table's limits

Let $X=\{x\in \mathbb R^n|a\leq x_i\leq b\}$. There exist some quantization of $x$ to a space $Y={y_1,y_2,\ldots ,y_n}$ with respect to a look up table (LUT) with $n+1$ limit positions $l_i$. The LUT ...
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1answer
44 views

What are some efficient algorithms for real-time calculation of eigenvalues?

I need to calculate eigenvalues of a square matrix for a real-time implementation using microcontrollers or dSPACE. Obviously, I can find the eigenvalues of a 2by2 matrix analytically. I am wondering ...
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69 views

Multilateration of Sound in 3D Space

TL:DR - How can you find the 3D coordinates of a emitter than transmits an impulse signal? STORY: I'm working on something to improve my bird-watching. I've got a camera that can take pictures of ...
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1answer
174 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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48 views

Algorithm/Code for finding surface shape of an image?

Is it possible to find the surface shape of an image as mentioned in the reference question ? If I find the unknowns of the equation , then what should be my next step in determining the shape of the ...
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1answer
31 views

Is sparsity induced penalty in source separation “Entrywise matrix norms”?

I am reading this paper where they introduce norm penalties for source separation. In table 1, the $\log/ l_1$ type is $\sum_{g} log(\epsilon + \lVert H_{g} \rVert_1)$. I wonder this $\lVert H_{g} \...
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1answer
488 views

Understanding FFT: FFT size and bins

I'm trying to implement an FFT to understand how it works. I'm using a random sound file (so i can't control the size of the signal), with a sampling frequency of 44,1Khz. I'm using this library ...
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1answer
78 views

Method for finding the best non-increasing approximation function of a given signal

I have a discrete-time signal (with noise) and I want to determine the best non-increasing function that represents it. Of course it would be useful if the obtained function were defined in terms of ...
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33 views

Recursive systematic convolutional code with TCM

My question is: What are the outputs from the TCM encoder ?
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1answer
109 views

Doubts on LMS derivation

I have been trying to follow the Least Mean Square(LMS) algorithm derivation given by Wikipedia here and have the following questions. Here I expected $y(n)$ is to be computed by convolving $x(n)$ ...
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1answer
118 views

Computational Complexity of Polyphase Resampling

does someone know the approximate computational complexity of a polyphase resampling algorithm? I am trying to find a good argument to prefer a polyphase resampling of Scipy over the FFT resampling ...
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62 views

Selection of transforms, windows, wavelets for current signal analysis

I am new to this topic but I already read about the propperties of different signal analysis methods. I am stuck with the obvious advantages of FFT, STFT and Wavelet transforms but can't find good ...
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31 views

In NMF: How to decide which matrix can be applied group sparsity constraint

In simple setting, my signal has specific pattern peak detected at some minutes like in $V$ matrix. I have prior knowledge that $V$ can be mixed from 6 patterns which is belong to 2 groups but cannot ...
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102 views

Designing feedforward delay/comb filter

I wrote a small delay/comb filter and have some questions about the way these things are normally designed. Background Initially I had a simple feedback (IIR) filter. It went something like this (...
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53 views

IMU gyroscope calibration based on accelerometer values

I need to calibrate some IMUs for a project. I am planning on using an algorithm proposed by Alberto Pretto et al (Google Shcolar link), based on two assumptions: The common the magnitude of the ...
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1answer
49 views

Clustering algorithm [closed]

I am looking for some suggestions regarding clustering. Lets say I have 5 subjects (1, 2, 3, 4 and 5) ...
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1answer
112 views

Approximating a Gaussian Process

Suppose that $\theta_t$ is an exogenous variable with known Gaussian process. Next, suppose that for any index $i\in [0,1]$, $$ a_{i,t} = (1-\beta)\mathbb E[\theta_t|\mathcal I_{i,t}]+\beta \mathbb E[...
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60 views

Does anyone know of any DLT implementation where the mining is used for useful data processing?

In nowadays Distributed Ledger Tech (most commonly blockchains and Tangle), the "mining" of a new block is perpetrated with little more use than reaffirming the Laws of Thermodynamics. There are ...
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2answers
97 views

recognize unwanted sounds, noises, and deleting them algorithm

I have a function that I need to use denoise algorithm on. What I thought is to divide it to smaller parts and then use Fourier Transform on each one of the parts, but I am not sure what to do next. ...
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32 views

Accelerometer to track Potholes

So I am trying to make an application to track potholes in a road. I am using accelerometer readings for that. Assuming that the phone is mounted in a car and our orientation doesn't change. After ...
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2answers
88 views

How to label sound events in noisy .wav files

I'm trying to find a way of automatically identifying birdsong in phone-recorded sound files (1min long). Currently the algorithm I'm using doesn't label all of the events I want it to. (it is ...
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1answer
76 views

Finding good feedback coefficients for basic reverb

I'm currently working on some reverb algorithm code for the Gamebody Advance to get a bit of that ambient feeling for the music instead of having plain dull sound. A few challanging restrictions are ...
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1answer
35 views

Engine for Google / Browsers to detect manipulated images? [closed]

Would it be possible for Google and web browsers to scan images and detect doctored photos? For example, a web browser could check for abnormal color gradients and signals that indicate if a photo ...
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1answer
939 views

Improving Template Matching Algorithm for OpenCV

Car detection using OpenCV I am working on a small personal project where i have to know wether an image shown is a car or not. I am using the basic OpenCV python based template matching. Positive ...
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1answer
138 views

Introduction to fast algorithms for time–frequency analysis

I had preliminary knowledge of digital signal processing from Oppenheim's Discrete-Time Signal Processing and is studying time-frequency analysis now. May someone suggest introductory reference (...
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1answer
69 views

Combining different Likelihoods - Particle Filter

I am new to particle filters and have a problem when it comes to the weightening (using SIR to be precise). The problem is that my different state-variables are subject to different noise-...
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1answer
754 views

Finding notes played in an audio clip

I am working on a program that will be able to tell when a musical note is played in audio and what that note is (ie. guitar or piano). You can assume can assume any audio used for the program will be ...
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3answers
284 views

Fast way to calculate a few points in convolution?

Say I have two 1000-point sequences. I can compute the entire convolution fairly efficiently using FFTs (keeping in mind that zeroes have to be padded on to avoid doing a circular convolution). ...