Adaptive Cancellation of Scattered Interference.
ADAPTIVE SENSORS INC SANTA MONICA CA
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This is the final report on a l-year study of adaptive arrays in a scattered jamming environment. It is assumed that the jamming signals are scattered into the main receiving beam of radar or communication system. The scattering medium could be terrain, rain, or chaff. Conventional adaptive nulling which uses an angular discrimination cannot be used against this type of interference without also nulling the desired signal, since both the scatterers and signal source are in the main beam. A method of cancelling the scattered jamming signals is outlined in this report. The theory of this type of adaptive cancellation, presented in earlier reports on this contract, is also reviewed. The technique for cancelling scattered jamming uses delayed replicas of the jamming signal. Since the area or volume of scatterers may be large, the resulting adaptive canceller may require a large number of adaptive weights e.g, 1000 or more. This suggests a complicated adaptive system and the importance of devising methods of simplifying the adaptive weight computation. It has been shown that the required number of adaptive degrees of freedom depends on the frequency spectrum of the jamming. With wide band noise jamming, this frequency spectrum depends on the receivers which can be designed to facilitate scatter cancellation. In earlier reports, two frequency spectra have been investigated, the rectangular bandlimited spectrum and the Gaussian spectrum.
- Radar Countermeasures
- Active and Passive Radar Detection and Equipment
- Non-Radio Communications