Chaotic radio for audio communications

Chaotic wireless communication system suitable for audio transmission has been designed and implemented. The chaotic module was based on Chua's circuit and it has been realized from inductor, capacitor, resistor, and non-linear negative resistor. The negative non-linear resistor was constructed from resistors and operational amplifier. Chaotic masking technique has been selected as a mean of chaotic data modulation whereas synchronization relies on Pecora-Carroll technique. The chaotically-modulated signal has been further frequency modulated to frequency centered at 9 MHz making the system immune to non-linearity of the communication channel. Such frequency modulation process was achieved by voltage-controlled oscillator inside 74HC4046 IC. On the receiving end, the FM demodulation was performed by employing phase-locked loop technique. Measured results of the presented radio system are also given.