Direct signal generation for chaos communication and chaotic measurement by analog PLL

Chaotic signals are used as carriers in chaos communication and as excitations in chaotic measurements. In both applications chaos generators providing prescribed signal power in a specified frequency band are required. The chaotic attractor used for signal generation has to be robust against variations in circuit temperature, parameters, etc. In order to get optimum performance, wideband signals are required and the chaotic waveform may not become periodic or almost periodic for many periods. The analog phase-locked loop (APLL) offers a very simple and robust solution for the chaotic signal generation. Its dynamics are very rich compared to the conventional chaos generators. The paper presents the bifurcation diagram of the APLL and studies the waveforms and spectra belonging to the different control parameters in order to find the best values for the chaos communication and chaotic measurements. The control parameters of a chaotic attractor may vary in an implemented circuit due to aging, temperature variation, etc. The stability of generated waveforms is also checked.