Questions tagged [spatial]

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Question on spatial sampling for non-linear and/or non-uniform arrays

I am a little confused as to how to compute the nyquist criterion for a sensor array that is not linear, and/or non-uniform. For the linear, uniformly spaced case, the spatial nyquist is delimited by ...
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Physical Interpretation of $\mathbf A$ beamforming Matrix

The directivity of an array is defined as: $$ D = \frac{1}{2} \int_{-1}^{1} \lvert B_{u}(u)\rvert^{2} du$$ Where $B_{u}(\cdot) = \mathbf{w}^{H} \mathbf{v}(\cdot) $ is the beampattern of the array in ...
1
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179 views

How to calculate spectrogram from nonstationary, nonuniformly sampled signal

I have a high resolution 3D spatial signal (xy-elevation data collected via Terrestrial Laser Scan) with very nonuniform sampling (holes/shadows due to vegetation; point spread varies as a function of ...
1
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840 views

How to calculate the spatial frequency of an image in cycles per image

I have been attempting to calculate the spatial frequency of a colour image. I first converted it to grayscale and used a Fast Fourier transformation (fft2) that codes the quantity of each spatial ...
1
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Spatial resampling, how to smooth?

Sorry if this is not the right forum. Having a velocity grid in which a wave propagates, and given a certain spatial sampling of the grid, what kind of smoothing/interpolation should be used if the ...
0
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18 views

Multi channel signal enhancment inequality proof

Assume that $\mathbf{h}(f)$ is a spatial filter coeff vector, and $\mathbf{d}(f)$ is the steering vector. $\mathbf{\Phi_v}(f)$ is the correlation matrix of noise. How do i proof the following ...
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176 views

Use 2D FFT to replace 2D Discrete Fourier Transform (MATLAB)

I met a problem. I ran a code to implement the 2D discrete Fourier Transform, here is the code: ...