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The X station digital sample stream enters a delay line at the right and the
Y station digital sample stream enters another delay line at the left. Each Delay
element delays the respective digital sample stream by 1 sample.
Multiplier-accumulator modules (MAMs) accumulate and average X and Y samples at
different X-Y relative delays to produce points in the lag domain that
(roughly) trace out a sin(x)/x function (for a broad-band emission source).
These lag domain data points are then Fast-Fourier Transformed (FFT) to the
frequency domain to obtain the cross-power spectrum. More lag points or a longer
lag chain will produce more frequency points in the cross-power spectrum. If
only the total power in the spectrum is required, it can be obtained by finding
the peak of the function in the lag domain without having to go to the frequency
domain.
The correlated output from each interferometer in an antenna array can then
be analyzed or combined to produce the desired result.
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