Study Of Chaotic Characteristic Of L-PLC Channel And The Reversed Phase Overlay Scheme Of DCSK

The application prospect of low-voltage PLC technology(L-PLC) is quite widespread. The study of not only L-PLC channel characteristics but also its modulation techniques is important problems. In this study, the chaos theory is introduced to the research of L-PLC technology. The chaotic parameters of noise series measured from the L-PLC channel are calculated and analyzed to study the whole inherent laws of the channel. The performance of the DCSK and improved scheme is simulated and analyzed in the L-PLC channel model. The major work of this paper is as follows:Firstly, the scheme studying the chaotic characteristic of L-PLC channel noise based on its Kolmogorov entropy characteristic is proposed. The noise series of L-PLC network are measured using laboratory-designed device under different running conditions. After the phase space reconstruction of the series, the parameters are calculated, and then the chaotic characteristic of L-PLC channel is confirmed. In this paper, the Kolmogorov entropy of measured series is calculated and analyzed to study the chaotic characteristics of the channel.Secondly, the reversed-phase overlay demodulation scheme is put forward in this paper based on the pseudo retransmission characteristic of DCSK. The existing research and classification of chaos modulations are presented in this paper. Then the bit-error rate(BER) performance of DCSK scheme is studied in the L-PLC channel model made by the help of MATLAB. A phase inversion demodulation scheme is employed in the automatic repeat request(ARQ) system to reduce the noise effects, and it works. In the reversed-phase overlay demodulation scheme, the first and the second half-symbol signals within a code period are reversed-phase overlapped firstly. Then the variable for judgments is gotten from the related operations results of the overlaid signal with the first half-symbol signal. Theoretical analysis of the noise suppression capabilities of the program, and were carried out in the MATLAB simulation of BER performance.Thirdly, the software programme schemes of DCSK modem system with the core of TMS320F2812 for the L-PLC is designed and developed. The rich peripherals and DSP chip make the system high reliability, high-speed computing power and data processing capabilities. The chaotic signal is generated in the software part. Besides, the modulation, demodulation, communications with the PC, is as well as completed in the software.