Secrecy of Communications in Data Transmission by Impulses with Unknown Moments of Appearance and Disappearance

We carried out a comparative analysis of the algorithms for detect ing a rectangular impulse against Gaussian white noise under either authorized or unauthorized access to the t r ansmit ted data. We presupposed that for data transmission the binary communicat ion system is used and that the useful information in the data is whether the signal is present or absent. The case is that unauthorized access by the outsider takes place in the situat ion when the signal parameters are completely or part ially unknown. We then define the degree of the t ransmitted data secrecy by the secrecy rat io determining how highly the threshold signal-to-noise ratio increases when there is the unauthorized access instead of the authorized one.