Questions tagged [algorithms]

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

Filter by
Sorted by
Tagged with
1 vote
0 answers
18 views

TDoA self-calibration with a single calibration emitter

I've recently asked a similar question aiming at the same problem on Math.SE, for which I've set a bounty. Problem. I have a radio calibration transmitter with known fixed location $\langle t_x, t_y, ...
0 votes
0 answers
8 views

image preprocessing(filtering) : before or after undistortion and stereo rectification

I'm currently working on a stereo visual-slam program (using OpenCV). After I get the images, there are 2 preprocessing steps to be done : A) Undistort the images + stereo rectification B) Some ...
0 votes
0 answers
11 views

Problem with "Topological Structural Analysis of Digitized Binary Images by Border Following" by Suzuki Abe

I have a Problem with the Paper "Topological Structural Analysis of Digitized Binary Images by Border Following" by Suzuki and Abe. In the Chapter "Appendix I: The Formal Description of ...
0 votes
0 answers
9 views

Finding rectangle corners by using point cloud

I have a rectangle in the 3D scene, which I know its width and height. It is placed in the 3D scene like the image below. I can manually select all points on the rectangle by mouse click. Given the ...
11 votes
4 answers
14k views

Programming a Vocoder

I'm want to program my own vocoder synthesizer like "Songify" but I can't find a simple of vocoder algorithm. Maybe you can explain or tell where to look for information on how vocoder works.
5 votes
1 answer
11k 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 ...
0 votes
1 answer
1k views

GCC-PHAT cross correlation

I am trying to implement GCC-PHAT in python. The approach is similar to the following two links: link1 and link2 It seems the only difference between GCC-PHAT and normal cross-correlation using FFT ...
0 votes
1 answer
57 views

convert from binary to hexadecimal according to the algorithm "keeloq"

Good afternoon. I have the key to my gate. I received its recording in the form of a PWM pulse train. Instead, I converted the impulses into binary code. Now I should get the hex numbers but it doesn'...
11 votes
6 answers
7k views

Kalman Filter - Implementation, Parameters and Tuning

First of all, this is the first time I try to make a Kalman filter. I earlier posted the follwoing question Filter out noise and variations from speed values on StackOverflow which describes the ...
0 votes
1 answer
35 views

Implementing an L-System conversion from R2 to R1 for symmetric, square matrices

I have been reading for some time about L-Systems, and specifically the Hilbert Space filling curve. I am interested in writing a function to convert upper-triangular matrix coordinates into an ...
-1 votes
1 answer
181 views

Wrong values calculating FFT with EEG Bands using Numpy

First of all I have to say I am very new to these matters. I am trying to apply FFT algorithm to some values obtained by EEG bands. I found the following code but I am unable to make it work correctly....
3 votes
1 answer
349 views

How to get a Standard Deviation weighted average in image?

Now I'm trying to implement a SDLWGW algorithm by the MATLAB. currently I'm referencing from Automatic White Balancing Using Luminance Component and Standard Deviation of RGB Components The problem is ...
5 votes
2 answers
2k views

Pisarenko Harmonic Decomposition

I'm attempting to code Pisarenko's method for some time-series data that I have. I've had a look at a couple of papers, which explain in detail the theory behind it, but I'm having some trouble ...
0 votes
1 answer
589 views

Need Help with Time-Stretching WSOLA Algorithm

I’m having problems implementing time-stretching using the Wave Similarity Overlap Add (WSOLA) algorithm. I got the basic OLA algorithm working first and then added wave alignment using cross-...
1 vote
2 answers
55 views

Which of an array's contiguous subarrays is an algorithm best applied to?

A function $f$ accepts two equally-long arrays $A$ and $B$ as input, and returns a real number $s$ such that the root mean square of $A-sB$ is minimal. I'm hoping to come up with a better-than-brute-...
0 votes
0 answers
31 views

How to decided the score threshold in speaker recognition?

I am new to speaker recognition and now starting from the GMM-UBM algorithm. Say I have a pre-trained UBM and speech from target speakers ...
1 vote
1 answer
193 views

Separation of signals without loss of information about the signals themselves

There is a signal that contains: Rectangular pulses on frequency of 1 kHz Rectangular pulses on frequency of 1.4 kHz Other noises. Required: Separate 1kHz pulses from everything else and measure ...
-1 votes
1 answer
150 views

How to automatically identify a surge in a periodic signal

Say I have a periodic signal i.e. Sine wave, which sometimes can have spikes that are 100% larger than the peak value. These spikes can be periodic as well. I'm trying to find an algorithm that could ...
0 votes
1 answer
48 views

What difference AoA algorithm between 4x4 URA and 12 elements square shaped?

I'm reading a paper from Lund University. They show the measurement and compare the accuracy of 3 types of arrays. The interest and question I got are two types, 4x4 URA and 12 elements square-shaped. ...
1 vote
1 answer
118 views

How do I implement a footstep recognition algorithm? One that recognizes the start and end points of each footstep?

I have some time series data captured from a person's footsteps/strides (specifically, a person on rollerblades). It came from an IMU sensor placed on a person's boot. Each data point captures ...
-1 votes
1 answer
174 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[...
14 votes
2 answers
3k views

What Is the Algorithm Behind Photoshop's "Black and White" Adjustment Layer?

Can someone explain the algorithm behind the "Black and White" adjustment layer in photoshop? I have to reproduce it using C++ for an application that emphasizes non-red/magenta(ish) pixels ...
2 votes
1 answer
2k views

Are there any signal processing libraries that implement TD-PSOLA?

For such a popular and old algorithm, I've had surprisingly little luck finding implementations. I've got it working in MATLAB, but am curious if any other languages have libraries containing it (...
1 vote
0 answers
54 views

Why some implementation of Wavelet transform use reconstruction filter instead of decomposition filter?

I'm using MODWT (Maximal Overlap DWT) to extract features from a signal. Matlab implementation is using reconstruction filter instead of decomposition filter. In the first level of modwt decomposition,...
2 votes
2 answers
93 views

Are there any efficient algorithm to detect circular shape of arbitrary size in an image?

I have images that are 1278 by 1024. They are pictures of a certain product that is rectangular in shape and are about 25mm by 20mm. As a part of a quality inspection process using computer vision, ...
0 votes
1 answer
163 views

Evaluation of incremental sensor

Evaluating a volume flow incremental sensor does not deliver expected results. The pump of which the volume flow is to be measured has a hand-calculated flow rate of $$Q = \dfrac{n}{ 60 \;\mathrm{s/...
0 votes
0 answers
20 views

Automatic frequency extraction from periodogram

I'm measuring periodograms from quasiperiodic orbits in a 2D Hamiltonian system. I'm using the Welch filter, and a equally spaced time grid (+ simple FFT), see example figure below (bottom: signal - ...
0 votes
1 answer
3k views

Recursive systematic convolutional code (RSC) realization in MATLAB

How can I implement $\rm RSC(2,1,2)$ in MATLAB? Can I use convenc function to build RSC? The convenc function has 2 arguments: ...
-1 votes
1 answer
63 views

Convolution of a discrete continuous function for reconstruction

From chapter 9 page 198 of https://github.com/t4world/Computer-Graphics/blob/master/Fundamentals-of-Computer-Graphics-Fourth-Edition.pdf I am confused as to what this book's description is saying ...
8 votes
2 answers
1k views

Kernel Convolution in Frequency Domain - Cyclic Padding

I don't know whether this is the right place to post this, but I suppose it is. I know that frequency multiplication = circular convolution in time space for discrete signals (vectors). I also know ...
0 votes
0 answers
21 views

What is a good algorithm for filtering data from a sensor that occasionally malfunctioned?

I was in a lab and recorded some data from 2 pressure sensors. One worked perfectly (red line), the other one would send random data occasionally (blue line.) All of my values are supposed to be ...
0 votes
0 answers
52 views

How is the 'difference' of two audio tracks best computed, in order to maximise instrument isolation?

I'm hoping to improve the results of a simple application I've been working on, which aims to isolate as fully as possible the electric guitar heard (along with drums/bass/vocals) on a single track of ...
0 votes
0 answers
22 views

Algorithm for unique speaker detection

I have some speech data and I would like to know approximately how many unique speakers are there in it. A very crude way is to do it manually by randomly selecting a small sample set and taking the ...
3 votes
2 answers
4k views

Why do we need DFT when we already have DTFT/DTFS?

We already have DTFT so why do we need DFT? Please don't write DTFT is used for discrete, aperiodic signal which transfers in the frequency domain to periodic and continuous, but in DFT is discrete ...
1 vote
3 answers
715 views

range-doppler map to range-velocity map conversion

UPDATE 2.0 I think I've managed to produce the correct range-velocity map. I'm struggling with analytically calculating the range which I expect to see on the range-velocity map. Could someone please ...
24 votes
3 answers
11k views

Fastest Algorithm for Distance Transform

I am looking for the fastest available algorithm for distance transform. According to Image Processing Learning Resources - HIPR 2 (HYPERMEDIA IMAGE PROCESSING REFERENCE) - Morphology - Distance ...
1 vote
0 answers
1k views

Radix-8 butterfly with Winograd and Cooley-Tukey algorithm

I saw the Winograd radix-8 kernel algorithm below, shown in the image. Comparing to the mathematical formula of Cooley-Tukey, there is a multiplication by $\cos$ and $\sin(\pi/8)$, which can't be ...
1 vote
0 answers
35 views

Do CQT, FFT, and NNLS provide different "perspectives" on the original signal?

From a bird's-eye perspective, do CQT, FFT, and NNLS algorithms provide different "perspectives" on the original signal? Does each preference some features of the original signal? I'm using ...
0 votes
1 answer
39 views

Identifying a signal by its power spectrum

Background: There is a method in optics for determining the electric field of light (both intensity and phase) via a three step process: Add a known phase shift to the light (called the "...
1 vote
1 answer
133 views

When if an FFT more efficient than Goertzel?

Given a block, $x[n]$, of M samples. Calculating abs(fft(x)).^2 returns the power spectrum of that block through the use of a $M$-point FFT. I can calculate the same using Goertzel's algorithm. At ...
0 votes
1 answer
65 views

Non Radix-2 FFT Algorithms

I have 25,200 samples of data. My bandwidth is 12.6KHz and my Fs is 1.26MHz, I want to plot an Amplitude-Frequency Spectrum to display up to 100 different signals, that's on purpose (12,600 * 100 = 1,...
0 votes
0 answers
74 views

Dividing a data set into segments with consistent inner behavior, using segmentation algorithms and metrics for consistency

Context of the problem: I have signal data which was recorded in a software system and which shows the runtime of multiple processes over time. In total there are more than 900 processes each having ...
2 votes
1 answer
295 views

How do audiobook players manage to quickly speedup/slowdown playback speed without using more memory?

Many audiobook player apps on Android have a reading speed slider which lets us choose the reading speed e.g. 0.5x 0.75x 1.00x 1.25x 1.50x. This is time-stretching ...
0 votes
1 answer
91 views

Selecting subset of sequences so their sum has minimum variance?

I have a set of N real sequences and need to pick K sequences (with no replacement) such that their sum has the minimum variance. E.g. I have N=3 real sequences of length 5: ...
1 vote
1 answer
4k views

Why Is the Result of the Convolution of a Row and a Column a Two Dimensional Matrix?

I'm trying to understand a book chapter on "Algorithms For Efficient Computation of Convolution" (Also on Doc Droid or Scribd) and I know that when calculating the convolution of an image represented ...
0 votes
0 answers
10 views

Efficient Method to match vector time series where the vector entries may not line up

Asking here because I couldn’t find or didn’t have the right words to search for the answers online. Also sorry for no examples—gotta maintain my NDA for work. I have two N-dimensional vector time ...
7 votes
1 answer
652 views

How to Use the Walsh Hadamard Transform to Filter 24 bit RGB Color Values in a Localized Spatial Region?

After reading this Signal processing Stack Exchange article tonight, What Is the Walsh Hadamard Transform? How Could One Use It in Image Processing?, I became interested in applying the Walsh-Hadamard ...
0 votes
0 answers
36 views

Active noise control in LabVIEW using cRIO (FPGA and real-time module)

Has anyone tried to implement the example code in LabVIEW for active noise control usin the my CRIO controller? I have an experimental setup of two microphones (primary and error microphone) and two ...
15 votes
6 answers
6k views

What Approximation Techniques Exist for Computing the Square Root?

I have very limited resources as I'm working with a microcontroller. Is there a taylor-series expansion, common lookup table, or recursive approach? I'd prefer to do something without using math.h's ...
3 votes
1 answer
124 views

The power of signal processing when faced with hardware constraints

I am currently studying interferometry, but I have only just begun studying signal processing. I want to better understand the effect signal processing can have in maximising signal detection from ...

1
2 3 4 5
9