Detection of Spread Spectrum Transmissions Using Fluctuations of Correlation Estimators

A method for detection of a Direct-Sequence Spread Spectrum (DS-SS) communication hidden in the noise is proposed. Indeed, DS-SS signals are well-known for their low probability of interception: their statistics are similar to the statistics of a noise, and, furthermore, they are usually transmitted below the noise level. The proposed method is based on the uctuations of autocorrelation estimators. We show that, when a DS-SS signal is hidden in the noise, these uctuations increase. A theoretical analysis shows that detection is possible, even with very low signal to noise ratio at the detector input. Experimental results are provided to illustrate the approach. The method is also able to estimate the symbol period of the DS-SS signal.