# 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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### How to determine stripe width of a barcode

A barcode consists of alternating back and white stripes. Thin stripes are one "unit" wide. We'll assume fat stripes are 2 "units" wide. But how big is a "unit"? I can't ...
55 views

### Getting the magnitude and phase of a single specific frequency from an audio signal

Assuming I only care to calculate the magnitude and phase of ONE single frequency from a signal, how can I get this information without calculating anything else? For example I want to come up with an ...
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### Constant Q transform where you keep the window size constant (so Q is no longer constant)?

I've been working on implementing a constant Q transform to try and detect musical notes within an audio signal and I came across an issue. When trying to detect low frequencies the constant Q ...
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### algorithm for second order butterworth filter

I want to implement an algorithm for a second order butterworth filter on the form $H(s) = \dfrac{Y(s)}{U(s)}= \dfrac{1}{\left(\frac{s}{w_0}\right)^2+2\zeta\frac{s}{w_0}+1}$ I want to get it on the ...
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### How can I use a constant Q transform to detect low frequencies without making the buffer size too large?

I am trying to write code to detect musical notes within a signal. I have been reading up on different methods for extracting frequency information out of a signal to determine which notes were played ...
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### Unsupervised Real-Time Pattern Counting in Time Signal Data Without Prior Knowledge

I'm facing a problem and it seems I can't find a working solution since a few years. TLDR : Is there a well-known algorithm or NN-model that is able to autodetect and count patterns in a time signal ...
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### Can the Constant Q transform be implemented more efficiently using an FFT?

I am trying to implement a Constant Q transform in code and was wondering if there was an algorithm that took advantage of the FFT to speed up the calculation so it can be used efficiently in realtime ...
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### Doubts on implementation of a beamforming algorithm to produce narrower beams

I am trying to understand and implement in MATLAB, the algorithm described in the paper A Beamforming Method Based on Polarization Matching but my math background is not strong nor am I used to ...
1 vote
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### --Which dither to use for narrowband speech?

The tl;dr What dither algorithm should I use when converting 24/48 mono speech to 8/8? -- I'm truncating and downsampling a 24/48 mono audio source containing only speech to 8/8. I won't be doing any ...
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### Efficient computation of 2^x (antilog2) for fixed-point

I've created a log2 AGC for an FPGA project, similar to Dan Boschen's solution in this question. I implemented a hardware version of log2 based on Dan's linked page in the previous question - ...
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### Exact computation cost using Forward Procedure for HMM probability evaluation

I am understanding the HMM concept for Speech Recognition. One of the three problems (HMM) to be solved is Probability evaluation $P(O|\lambda)$. Instead of a straightforward approach which is ...
77 views

### Fit Data Samples with a Robust Fit

I have a data from a sensor which the connection model of $x$ and $y$ is known: For instance, in the case above, the model is linear. The issue is how to handle outliers. Specifically when there are ...
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### Differential value range reduction for Huffman encoding

I am trying to understand a piece of coding technology and place it in its context, but I am unable to find any literature on the subject. It would be much appreciated if someone could point me in the ...
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### Why do extremals need to be located at the left-hand and right-hand band edges of each band?

I am reading the Remez algorithm for designing FIR filters. In the first paragraph of section 15.3.1 of Andreas Antoniou's digital signal processing book, I have two questions. extremals are to be ...
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### What algorithms exist for dynamic audio normalization?

I'm manually editing the WAV files for an audiobook. There are often sections where I have to amplify a section, and then amplify sub-sections due to the variability of the quality of the original ...
1 vote
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### implement gradient descent with sparsification algorithm

I am trying to implement the algorithm in this paper for finding a sparse vector x that minimizes the square error $\lVert y − \Phi x\rVert_2^2$ where $\Phi$ need to satisfy the restricted isometry ...
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1 vote
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### Is fft always the best choice?

I hope this is the right place to ask this question since it is partially a note which might help others. Until recently, I always used the fft-algorithm ...
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### What is the name of a low-pass filter that tracks rate of change?

When applying a low-pass filter to a constantly changing signal, there will be a lag between the actual value and the filtered value. For example, if f(x) = x, the ...
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### Cfar Algorithm Implementation

I am trying to implementation Cfar algorithm to our radar signal processing algorithm. I obtained some output but I want to be sure that is right. Cfar algorithm's output below like, I'm interpreting ...
56 views

### How to detect known audio samples within a stream of audio

If I've got a bunch of short .wav files, 16 bit linear pcm, and an incoming stream of audio that's been run through a voice codec (g.722, g.711, or others) and then converted back to pcm, what's the ...
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1 vote
63 views

### Measure of how well sounds fit together in a composition

Are there any approaches to gauge how well a sound may sit together with other sounds in a mix? I’m thinking about something similar to picking instruments that might go well together in a band. ...
1 vote
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### How should I go about calculating sines or cosines without the errors introduced solely by the transcendence of pi?

This may be irrelevant for many people but I'm asking this question because I don't need to do these things in real time, I don't care if modifying a 1-minute sound recording takes 5 minutes to ...
302 views

### What is the equation I can use to create the inverse expoential graph?

I am seeking an equation I can apply to provide a score based on a measurable ability rating. It would be great to understand how the equation works so I can alter the curvature of this flexibly based ...
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### How to use MUltiple SIgnal Classification (MUSIC) algorithm to detect the wavenumber of a received signal at array of sensors?

I am working on analyzing data obtained from Fiber Optic - Distributed Acoustic Sensor (DAS) to estimate the properties of acoustic waves that impinge FO cable, such as velocity of acoustic waves. FO-...
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### MUltiple SIgnal Classification (MUSIC) for Frequency Estimation

I am trying to use MUSIC algorithm to detect individual frequencies of an incident signal. I read the original paper and some interesting books that explain the algorithm. I used the following ...
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### MUSIC Algorithm for 2D Power Spectrum

I am trying to use Frequency-wavenumber analysis for estimating speed of sound using two-dimensional data obtained via channel of arrays. The traditional technique is to use FFT to transform the data ...
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### Model validation- comparing signals

Let's say I am trying to validate a model. I have a signal from measurement and a signal from the simulation of the model. Simulation was done with the same initial and boundary conditions as ...
1 vote
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### DSP function used by musical distortion plugins

In short: what kind of mathematical function was applied to this sine WAVE? I am trying to implement my own distortion plugins. Amongst other things I have read several chapters of Will Pirkle's book (...
962 views

### How to measure aliasing?

Aliasing is bad, and we want good filters when downsampling. While what qualifies as aliasing is well-defined mathematically, and we can manually design filters with various tradeoffs, how do we ...
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### model of a quasi static block fading channel in MIMO system

can I know what is the model of a quasi static block fading channel in a MIMO system, in function of angle of departure and arrival?
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### Is there any method to incorporate boundary periodic conditions into the kernel summation over unstructured data points?

Supposing that there are $N$ particles distributed inside a periodic cubic box of volume $V=L^3$, I want to divide the cube into a regular mesh and calculate the following summation at each grid point ...
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1 vote
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### Measures of "coincidence"?

Assuming I have two sensor feeds, is there an algorithm that gives an estimate of how likely it is that they point at/derive data from the same scene (possibly from different angles, with different ...
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### Identify abrupt changes in an audio waveform

I have an audio file which was created by substituting multiple speech segments into an original utterance. I want to find the timestamps where such substitutions happened, so I guess that one thing I ...
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### What are the step by step actions taken in order to convert PDM data to PCM data?

I would like to convert PDM (Pulse Density Modulation) microphone data into PCM (Pulse Code Modulation) data. I understand that ...
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### Different kinds of beeps and tones

I have heard many different types of beeps, chimes, and other tones. Audacity allows me to generate simple waveforms like sine waves and square waves, as well as DTMF tones. But I want to generate ...
138 views

### Finding start point of a curve

I'm currently working on a project where I have to measure the latency of a given system. Below you can see a exemplary image which shows the input pulse (green) and the response (blue). In order to ...
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### Choosing the scaling parameters for a modem implementation

I have succesfully modeled a modem using floating-point data and with the following scheme, where the SRRC filter has gain G=6dB. ...
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### Algorithm for Hue correction behind HSL sliders in image processing software

I have a project where i need to recreate hue specific hue adjustment sliders like in Lightroom/Capture One/DxO photolab. Initial image. Image after hue adjustment (Orange hue range) in DxO Photolab....
1 vote
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### Steering Vectors and Bluetooth Low Energy for computing Angle of Arrival

I am new to signal processing, but I have background in mathematics. I am trying to use Bluetooth Low Energy (BLE) on three mobile devices, where one device is being tracked and the other two act as ...
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### What is the point of using this derived PID controller?

Previously, I answer for this PID controller that I want to understand completly. This is used for control the opening $U_n$ of a valve let gas pass and reach a certain pressure (SetPoint). There is ...
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### Conceptual doubt about PID algorithm in PLC

I have to use the PID algorithm that I describe below, obtained from a PLC in the company where I work, so I want to understand it. This is used for control a valve that opens to let gas pass and ...
368 views

### Is there an analogue to the 2D DFT that is rotation equivariant?

I'd like to know if there is some general Fourier transform or other signal processing algorithm, such as a discrete wavelet transform, that is rotation equivariant. Rotational equivariance of a ...
271 views

### How to detect signal in spectrum without empirical data

Let's say, I have got a spectrum of a signal with noise using fft: For a human it's pretty obvious that there is a signal with a frequency of about 51Hz. But what is the mathematical apparatus behind ...
239 views

### How do I do a point response FMCW SAR simulation?

I am trying to simulate and focus the point response for an FMCW stripmap SAR system. I have specified my target coordinates as targets = [100,100,0;400,100,0] and ...
157 views

### Are there algorithms to compare changes in signal amplitudes?

I am working on a project to reduce resonances caused by motors. The vibrations in the material are measured and sampled by ADCs. The measuring works as intended and the next step is to reduce the ...
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### Implement Quinn’s second estimator for frequency estimation

I am trying to get the estimation frequency from the FFT output in unity, I have read that Quinn's second estimator method is the most accurate method, and I found the algorithm for how to implement ...
1 vote
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### Weird Noise arises on the small scales: one question about the fast CWT algorithm implemented in real space

Background: I am learning an interesting Fast CWT algorithm(PPCWT) by reading this paper published in 2019. The algorithm is summarized as below. The continuous wavelet transform of a signal can be ...
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### Spectrogram of a shock event

I have measured data of a vibration with chirp input were I suspect unwanted shock events occurred. I therefore thought about computing the spectrogram of my time histories to check the frequency ...
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