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Abstract

The present invention is directed to a digital non-coherent pattern detection scheme in which spectral analysis of phase encoded signals is utilized to provide pattern recognition. The present invention is relatively insensitive to the power level of incoming signals. Since the power level is easily detected and determined, the present invention allows the various algorithms to operate quickly. Further, utilizing the magnitude samples of the incoming signal result in a pattern detection scheme that is independent of modulation technique. The present invention utilizes the concept of spectral analysis to determine spectral lines which are present in phase encoded signals. A phase encoded signal such as a DPSK or QAM having an implicit pattern contained therein, which results in unique spectral lines. By detecting the spectral lines in certain combinations, the phase encoded pattern being sent may be identified. For example, 'unscrambled mark', 'S1', and other patterns may be identified using the method of the present invention. In operation, a plurality of receive channels are implemented to detect energy levels at specific frequencies and thereby identify spectral lines. The input signal is demodulated with one of a plurality of modulating frequencies F.sub.0 -F.sub.n in each receive channel, chosen to translate the input spectra signal to baseband. The demodulated signal is low pass filtered and the filtered output is squared, generating a power signal. In the preferred embodiment, the power signal is filtered again to obtain a stochastic average. This averaged signal is coupled to an energy detect block. If energy at the desired spectra is present and of sufficient magnitude, a digital 'one' is provided as output, if sufficient energy is detected, a digital 'zero' is provided as output. A logical 'one' is provided at the output representing the specific pattern detected as indicated by the digital word.

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First Claim