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Advanced LPI (Low-Probability-of-Intercept) Intercept Detector Research

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Final rept.

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We examine in this report the problem of wideband detection of a spread spectrum signal from an interceptors viewpoint our aim is to derive, evaluate and compare various detector structures whose purpose is to intercept a spread-spectrum communication transmitter. The transmitter under surveillance employs a variety of modulationspreadingtransmission techniques which are invariably assumed to emit the message-bearing signal in deep background noise or interference. Thus, the challenging task of the intercepting detector is to reveal as best as possible any transmission of the unknown spread waveform in the presence of an obscuring noisy environment. Naturally, the degree of success achieved by the interceptor when detecting the presence of the communicators spread signal depends on the amount of information available to him regarding the structure of that signal. At one extreme, the interceptors most fortunate situation would be to acquire the spreading code itself crack the code. If this is too demanding, he must settle for less, such as approximate knowledge of the signals carrier center frequency, code rate, code epoch, spreading bandwidth, etc., or a subset thereof. At the other extreme, he might know almost nothing, in which case, he could resort to a simple energy discriminator device i.e., radiometer since it is, on many occasions, a low-SNR asymptotically optimal detector. In this report our main interest is to investigate the possibility that the interceptor could do better by optimally processing whatever information is available to him between the two extremes cited above.

Subject Categories:

  • Active and Passive Radar Detection and Equipment
  • Non-Radio Communications

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