Time-varying reconstruction of stationary processes subjected to analogue periodic scrambling

In modern telecommunications, it is often desirable to scramble the contents of the information. This paper presents a particularly efficient method of analogue signal scrambling. A stationary process is subjected to scrambling by means of a linear periodic time-varying filter. We observe then a cyclostationary process. We demonstrate that perfect reconstruction is possible. In presence of overlapping spectra, unscrambling requires a time-varying filter. We apply this method to scramble stationary binary signals. Simulations show that the system is additive noise resistant