Questions tagged [array-signal-processing]

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Basis Pursuit Denoising (BPDN) algorithm for Direction of Arrival Estimation

I am working on Compressive sensing algorithms for DOA estimation. Can i get any references for writing BPDN code in MATLAB.
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1 vote
2 answers
51 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-...
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8 votes
1 answer
143 views

MUSIC Algorithm for Direction of Arrival (DOA) in Acoustic Signals

I have seen multiple reviews of the MUSIC algorithm for the estimation of DOA. Most of those reviews consider a complex signal input with a complex steering vector. So, how do I implement this ...
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108 views

What is going wrong with the plot of 2D spatial spectrum at a specific frequency?

I've a set of 09 sensors in the following arrangement and the script for the sensor positions as follows: ...
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pan tompkins algorithm and thresholding

so iam trying to understand the pan tompkins algorithm for QRS detection and i was curious about where did they deduce this threshold formula : Threshold $I_{l} = NPKI + 0.25 \left( SPKI - NPKI \right)...
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How do I make a graph of pseudo frequency vs. time. in ssqueezepy?

How do I make the y axis in psuedo-frequency? ...
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2 votes
1 answer
37 views

pan-tompkins algorithm

The difference equation of the differentiator used in pan-tompkins algorithm is as follows : ( a five-point derivative) $$ y \left( n T \right) = \frac{1}{8} T \left[-x \left(nT - 2 T \right) - 2x \...
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1 answer
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DSP based phase shifting in Phased Array systems

Is there a downside to doing phase shifting at basedband in the DSP section of phased Array systems? I suppose you trade off analog components for digital which may be more costly but I suspect modern ...
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1 vote
1 answer
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magnitude spectrum

I have an ECQ signal of 360 Hz sampling frequency. I used an FFT to extract the frequency spectrum of my signal. Now I don't know exactly how to interpret this plot. How can I know the noise from ...
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1 answer
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How to perform the 2d Vector Antenna in LabView for MUSIC Algroithm

I have 1 transmitted channel and 4 receiving channels on Uniform Linear Array (ULA) and I am using the MUSIC algorithm to determine the AoA of the incoming signals in LabView. Now I want to use the 2D ...
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4 votes
2 answers
146 views

MUSIC Algorithm in LabView not Working Well

I am working on performing the MUSIC Algorithm in LabView. The hardware testbed includes four phase-locked receiving channels and a coherent single-channel transmitter (first I will verify the MUSIC ...
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1 vote
1 answer
38 views

Simulation of Discrete Inverse Fourier Transform of an array in Python

So I have a simulation to get Fourier Transform of an given array. This is my Python code to get Fourier Transform ...
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4 answers
219 views

Finding the mode of propagation of a progressive wave and the velocity of that mode

Injecting a sinusoid say, $Z = A \sin(k_x X + k_y Y - \omega t)$, $K = 2 \pi f/c$, for example, assume $f = 10$ Hz or $50$ Hz, and $c = 50$ m/s, now if I draw the 2D K-space plot with the following ...
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3 votes
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Direction-of-Arrival estimates clustered at specific angles

I am having an issue which I cannot understand completely. I am working on a simple project where I am testing various algorithms from the family of the Generalised Cross Correlation [GCC] for ...
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pattern recognition with some features in time series data

I am trying to capture peaks in a time series data which has some predefined feature. Here is a snapshot of time-series data (Time series data with peaks) In this time-series I want to detect peaks ...
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1 vote
3 answers
103 views

Convert a list of values and times into an audio file

I have two pandas dataframe, one with time in seconds and one with the actual audio data (values from -1 to 1). The audio data points are not equidistant, this why I need the list of time in seconds. ...
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What are some good examples of applications of Circular Convolution in Signal Processing and Image Processing?

I have derived the circular convolution property for an affine Fractional Fourier Transform and I need to work on an application for my research. Any idea?
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I have two signals, recorded from the same device. How do I standardize/normalise them?

I essentially have two signals X and Y, recorded with PPG devices. These have been filtered already. I want to standardize(z-score) or min-max scale them but I don't know if I should do this on each ...
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1 vote
2 answers
70 views

Discrete Wavelet Transform (DWT) and wavelet family

I have just started reading about wavelets for a data compression problem that I want to perform. I am reading about Discrete Wavelet Transform (DWT) but I can't understand where the wavelet family ...
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2 votes
3 answers
123 views

What does the intensity values on wavelet transform mean? Amplitude or power?

So when applying wavelet transform, we get a 2d plot. Each point in that 2d plot has a color, showing intensity of something. But I cannot understand if it is an amplitude or power?
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1 answer
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Can FFT tells us existance of same frequencies with different phases?

So I know that applying FFT on a time-domain signal, shows which frequency components exists and what amplitudes each frequency signal has. My question is, suppose the signal contains same frequency ...
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  • 149
0 votes
1 answer
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Extracting different frequency bands (alpha, beta, gamma) from MEG source estimated data

I have a dataset that consists of source estimated data of MEG brain signals. I need to extract the different frequency band features (i.e., alpha, beta, gamma, etc) from them. What steps/procedure ...
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1 answer
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Calculating power of brain signals

I have a dataset that contains EEG (or MEG) recordings of brain signals during some cognitive tasks. Each row, shows the source estimates of neurons in a particular region. source estimate contains ...
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2 answers
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Why does my amplitude change upon inverse Fourier Transform when I am only randomizing the phase of the fourier transform using Python numpy?

I am trying to make a surrogate time series of a discrete data series using python, basically I wish to keep the amplitude same and change the frequency I take a Fourier Transform of the data I ...
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2 votes
2 answers
195 views

How to reconstruct the signal using overlapping frames in MATLAB

I understand that we can use the buffer function in matlab to split a long signal into overlapping frames. But is there any functions that we can use to put the ...
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3 votes
2 answers
183 views

Why do we need to estimate eigenvalues?

I am not working in signal processing field, but recently I happen to read a paper which estimates source numbers using Gerschgorin radii, and I feel kind of confused about why we need to estimate ...
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-1 votes
1 answer
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Visualise/compare numpy arrays from Matlab/Octave to matplotlib

I'm new to python and matplotlib, and I'd like to visualise / compare 3 mfcc files stored as numpy arrays in txt format. I have the Octave code below, and I'd like to know how it can be done using ...
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Signal-to-Noise ratio of multivariate stochastic process from Correlation Matrix

I'm not in signal processing, I'm from an another discipline. I've derived a simple result which I presume must be well known in SP and I'd like to know whether there's a paper or textbook that has it ...
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1 vote
1 answer
185 views

a neural network approach for FIR filter

I am trying to write a code for a neural network to do the digital filtering on some signals. Is there any neural network model for digital filtering?
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1 vote
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Spatial moving average in array antenna processing

In array processing the theoretical spatial response of the array is calculated by doing DFT on sensor locations for some assumed wave number (1/wavelength). The figures below shows the sensor ...
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0 votes
1 answer
134 views

Cross-correlation of two signals

I want to find the direction of a sound source in 2D space. I use two microphones and one sound source for that. I have recorded audio data into two arrays. When a sound is detected, it starts to ...
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0 answers
53 views

What is Ad-hoc microphone array?

I have stumbled upon this term in many papers, though no one bothers to elaborate. Is this the case where I do not have prior knowledge of the array structure? or otherwise is it the number of ...
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0 votes
1 answer
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Discrete Signal Windowing

How do we apply windowing of 50% (4 samples) to a discrete signal with the odd number of values as 1234567? Is it done as: ...
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3 votes
2 answers
999 views

MUltiple SIgnal Classification (MUSIC) Implementation

I have a linear 4 element antenna array currently in my design, I am able to obtain the I/Q data from each antenna. Now I am trying to implement the MUSIC algorithm to obtain the AoA (Angle of Arrival)...
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0 votes
0 answers
24 views

When does the narrowband model in array processing fail?

I am not sure that I understand well the narrowband assumption in array processing. I wonder how it simplifies the model and what would change if not assumed. Also, what will happen if I apply the ...
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0 votes
0 answers
28 views

Calculate the percentage of accuracy with which user made the assigned sound

I want to design a web-app for my cousin who is 2 years of age in which i have implemented a functionality in which when an image is clicked some sound gets played and the user has to make the same ...
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1 answer
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Zero peaks in fft data even after subtracting mean

I have a time series sensor data. It is for a period of 24 hours sampled every minute (so in total 1440 data points per day). I did a fft on this to see what are the dominant frequencies. But what I ...
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1 answer
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Python code for QPSK modulator [closed]

Have any of you done anything like QPSK Modulation in python? I am in the middle of it and having problems in setting up bits? like odd and even bits. Have you got any idea? Regards, Sam
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1 answer
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Question about eigendecomposition, signal subspace and their properties

Lately, I am readig a paper titled A Subspace Method for Estimating Sensor Gains and Phases. In it, it is mentioned: There are $m$ sensors in the array, $n$ known narrowband far-field signals($m \...
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2 votes
1 answer
242 views

Source Localization with the BLUE Estimator

I'm trying to implement BLUE estimator in MATLAB for source localization and after my research I've come up with a theoretical example in Steven Kay's "Fundamentals of Statistical Signal Processing: ...
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1 vote
0 answers
57 views

Sign of manifold vectors in monostatic phased-array radar

I am reading some notes where the impulse response of phased-array to is given by; $$ \beta S(\theta, \phi) \bar{S}^H(\theta, \phi) \cdot \delta(t-\tau) $$ where \begin{align} \bar{S}(\theta, \phi)...
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1 answer
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Detect when signal starts oscillating

I have a signal which consists of oscillations riding on square waves as shown in the image below. I wish to detect the time at which oscillatory events occur (as shown by the red star). Each square ...
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1 vote
1 answer
207 views

How do I create a polar plot from a multi-channel sound file?

I have a multi-channel sound file from a microphone array. I want to get the polar plot in Matlab in order to get the directivity patter of the sound source. How do I do this? I did the FFT on the ...
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5 votes
1 answer
729 views

Radar signal processing flow chart

I'm new to Radar in general, and I'm studying RADAR using online resources. I came across the following slide which shows the process flow of the Radar signal processing. The thing I don't get in ...
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3 votes
0 answers
139 views

How to compare imaginary coherence values?

High, I am currently writing my Master's thesis on susceptibility for hypnosis. I am comparing EGG signals of lowly and highly susceptible individuals. The imaginary coherence is given by: $$ \...
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0 votes
0 answers
26 views

Temporally synchronize two different or more real time digital audio signals

Are there any DSP techniques to temporally synchronize two different or more real-time digital audio signals without timestamp information?
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0 votes
1 answer
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Arbitrary shaped RIR generator

I wish to simulate some sound sources convolved with a Room Impulse Response (RIR) and impinging on a spherical microphone array. I could find a couple of generators online (such as this one), though ...
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-1 votes
1 answer
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Is it possible to estimate the DOA from real samples only?

I'm sampling a ULA with a scope after transmitting a CW. I'm wondering if I can estimate the DOA assuming I'm interested only in the range [0,90] [deg] and not the full [-90,90] [deg]. The first issue ...
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0 votes
1 answer
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The frequency-domain spectrum obtained using MATLAB's FFT function seems inaccurate

I am using MATLAB R2018b on a Windows 10 PC. In order to obtain the frequency domain information of a signal, I'm applying MATLAB's FFT function. The signal of interest is obtained from an experiment ...
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1 vote
2 answers
151 views

Number of microphone limitation for Spherical Harmonics based DOA estimation

I am following this book "Theory and Applications of Spherical Microphone Array Processing", as well as this paper on DOA estimation "Eigenbeam-ESPRIT for DOA-Vector Estimation". My dataset is ...
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