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I do have an overview of basic radar signal processing chain [Data cube, 3 stages of FFT, Range, Range-Doppler map, coherent/non-coherent integration, coarse DoA etc.].

I am now trying to understand an advanced DoA estimation technique-MUSIC and one of the road blocks is the snapshot concept. Nearly every paper retrieved from google assumes an prior understanding of snapshots and am yet to find one that tells me what exactly is it.

So, what are snapshots in DoA estimation?

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  • $\begingroup$ What is your guess? Hint: Snapshot in common language is a picture, i.e., an instant in time. A picture is a 2-D array of intensities. $\endgroup$ – learner Aug 31 '17 at 4:17
  • $\begingroup$ @learner- That precisely is the dilemma. Snapshot of what? Snapshot of raw ADC samples of all receivers taken at the same exact time? Snapshot of a specific range-doppler bin of all receivers? The term snapshot is excruciatingly overloaded. $\endgroup$ – Raj Aug 31 '17 at 4:50
  • $\begingroup$ MUSIC refers to snapshot of raw ADC samples of all receiver taken at exactly same time. This means, first, ADCs need to be in sync. Second, the difference in length of physical channel leading to each ADC needs to be compensated for. $\endgroup$ – learner Aug 31 '17 at 10:23
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A snapshot is simply a data capture (sample window) of ADC samples from all receivers, that we know holds all the information to resolve what we need (distance and/or direction) given the various dimensions involved (transmit pulse length, nearest possible target distance, farthest possible distance, maximum array dimension, and the echo wavelet length). This defines the delay (from start of transmit time) of the window and the length of the window. The literature refers to a "snapshot" because many systems can repeatedly take snapshots to integrate-out noise, etc., but other cheaper systems can't.

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