MEASUREMENT OF LONG-WAVELENGTH COSMIC NOISE BY ZERO-CROSSING INTERFEROMETRIC APERTURE SYNTHESIS.
Final rept., 1 Oct 62-30 Sep 65,
RESEARCH LAB OF ELECTRONICS MASS INST OF TECH CAMBRIDGE
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A unique measurement system offering the possibility of mapping cosmic radiation at 100-1000 meter wavelengths with angular resolution of approximately 1 degree is described. The system requires an orbiting satellite pair to get above the ionosphere. An aperture synthesis method with a variable radio base line involving a technique of zero-crossing spatial crosscorrelation of clipped signals is described. The system offers a method of digital signal processing to achieve high angular resolution and dynamic range at low frequencies without erecting large arrays in space. The use of zero crossings in the digital signal processing permits a significant reduction in the data that must be processed in the satellite without sacrificing accuracy. The techniques described become easier to instrument the lower the measurement frequency of interest. The complexity of the system is independent of the maximum radio base line required. The techniques may be instrumented at frequencies as low as the interplanetary cutoff frequency at about 50 kcsec. Author