Covert Digital Communication Using Random Frequency Hopped Spread-Spectrum

In this paper, it is proposed a novel secure communication system based on random frequency-hopping. The transmitter generates a carrier which consists of certain number of sinusoidal signals having constant duration and random frequency taken from a prescribed probability density function depending on the binary information. The covertness of the proposed transceiver is analyzed in terms of autocorrelation of the instantaneous frequency. It is shown that instantaneous frequency within constant bit duration exhibits autocorrelation of actual noise. The non-coherent detection is performed by estimating peak frequencies within each hopping time interval and the resultant receiver utilizes the statistical information to determine the transmitted message bit.