# A Data Secured Communication System Design Procedure with a Chaotic Carrier and Synergetic Observer
## 5 Discussion  
The designed system is presented in the form of a MATLAB/Simulink model, and the results of computer modeling of the constructed system are presented above. The simulation results confirm the viability of our approach. Moreover, earlier we have studied the cryptographic strength and steganography for another 3 rd order chaotic system with parametric modulation of only one parameter introduced into the system in a non-linear manner, i.e., multiplicatively using the autocorrelation method and the Fourier transform. As a result, autocorrelation has shown the complete identity of the signal analysis results with and without the added useful signal component. Analysis by the Fourier transform method has shown that the difference in the level of the leading frequency of the Fourier transform spectrograms is only 0.002 Hz for signals with and without the useful information  
Figure 22: Test images: (**a**) Test black and white image with 256 gradations of the gray level at the system input; (**b**) Signal in the communication channel; (**c**) Restored image.  
component, which will not allow detecting the existence of the useful signal by an external listener In our current studies, we have applied these methods, validated in previous research to build the two-channel transmission system presented here.  
The approach to low-level protection of transmitted data used in this work is extremely effective and, with the exception of cases of the simplest implementation of a coding and communication system, allows good protection of the transmitted information [12; 13], including hiding the data and even the fact of its transmission, not allowing a malicious observer to determine or extract any useful signal from the noise in the communication channel. This idea was repeatedly considered in the work of various previous authors, however the implementation of this approach turned out to be difficult due to a number of problems with decryption of such a protected signal on the receiver side. A general description of the use of synergetic observers in systems with chaotic dynamics is given by [PERSON] et al. [39], and the procedure for a single-channel system was presented in previous research [42; 43]. In this regard, the present study, which allows developing a two-channel reconstruction technique for two useful signals masked by chaotic oscillations on the receiving side, can provide a practical implementation of a very promising and practical approach for developing new communication systems for transmitting signals with a chaotic carrier.  
In this study we did not use the simplest forms of parametric modulation. In many other well-known works using the parametric modulation method the useful signal is added to the model of the chaotic generator as an additive component (e.g., [46]), but we use an approach in which the useful signal is added as a multiplicative component, i.e., we use \"non-linear mixing\", which will have greater security. Our procedure applied to the 3 rd order model of the chaotic system. According to Figure 13, we can see a reconstruction error rate up 25% of the original signal or even more, but mainly this error has the form of a short-time disturbance and may be eliminated with basic smoothing and filtration algorithms.