Compact Architecture For Spectrum Analysis And Correlation
John M. Pellegrino, Norman J. Berg, Michael W. Casseday, Andree N. Filipov · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1984
An acousto-optic architecture for simultaneously obtaining time integration correlation and high-speed power spectrum analysis has been constructed using commercially available Te02 modulators and photodiode detector-arrays. The correlator section of the processor uses coherent interferometry to attain maximum bandwidth and dynamic range while achieving a time-bandwidth product of 106. Two correlator outputs are achieved in this system configuration. One is optically filtered and magnified 2 : 1 to decrease the spatial frequency to a level where a 25-MHz bandwidth may be sampled by a 62-mm array with elements on 25-μm centers. The other output is magnified by a factor of 10 such that the center 4 μS of information is available for estimation of time-difference-of-arrival to within 10 ns. The Bragg cell spectrum-analyzer section, which also has two outputs, resolves a 25-MHz instantaneous bandwidth to 25 kHz and can determine discrete-frequency reception time to within 15 μs. A microprocessor combines spectrum analysis information with that obtained from the correlator.