ANALYSIS OF THE SECRECY OF DISCRETE CHAOTIC SIGNALS GENERATED USING A PARAMETRIC OSCILLATOR

Abstract

When developing modern radio technical systems (RTS) for the transmission of confidential information, there is a tendency to use signals whose properties are close to those of white noise. Such signals include chaotic sequences (cascades). However, possessing features of randomness, the simplest mathematical models of chaotic sequences have a structured image in phase space, which distinguishes them from ordinary white noise. Therefore, the direct use of chaotic sequences for the transmission of information does not solve the task of ensuring the secrecy of RTS. Nowadays, in connection with the development of digital methods of signal formation and processing, it has become possible to create sources of chaotic signals based on digital-analog devices, which are serially produced with different degrees of integration, which allow the formation of broadband and band signals with a larger radius of action for navigation, telecommunication and radar systems. The paper considers the method of constructing a class of chaotic signals based on a parametric oscillator, as well as the formation of continuous chaotic signals associated with them. A study of their secrecy was conducted. Visual analysis of the trajectories of interpolated chaotic signals on the phase plane allows us to assume that their structure is similar to the structure of the phase trajectory of correlated noise. This conclusion is confirmed by the value of the stealth coefficient kскр » 1 . Thus, the interpolation of discrete chaotic signals leads to a decrease in their stealth. Continuous broadband signals have the greatest stealth, for which fn = 0 . As the carrier frequency increases fn , when n ³ 2 , the stealth coefficient stabilizes and takes values smaller than for the case when n = 0 , this means that the hiddenness of band chaotic signals is less than that of broadband ones.