Narrow Results

In binary Differential Chaos Shift Keying (DCSK), the reference and information bearing chaotic wavelets are transmitted in two consecutive time slots. This TDMA approach provides two independent channels for the transmission of reference and information bearing wavelets but requires a delay component both in the modulator and demodulator circuits, furthermore, it halves the data attainable data rate. The wideband Radio Frequency (RF) delay lines at receiver are extremely difficult to implement with CMOS technology, therefore, the DCSK modulation cannot be exploited in many applications, such as ultra-wideband. To avoid the use of wideband RF delay lines at receiver, an alternative solution is proposed here where both the reference and information bearing wavelets are sent in the same time slot. The two wavelets are separated by Walsh codes instead of time delay. The new modulator and demodulator configurations are given, analytical expressions for the Bit Error Rate (BER) are derived and the derived BER expressions are verified by computer simulations over Additive White Gaussian Noise (AWGN) and multipath Rayleigh fading channels.

The chaotic delta sigma modulator is a way to suppress the limit cycle oscillation caused by the input of a null or constant signal. By changing integrator gains, the output sequence becomes chaotic and the noise characteristic of the output is changed. This noise characteristic is an important factor for evaluating the performance of delta sigma modulation. The aim of this study is to analyze the noise characteristic of chaotic double loop delta sigma modulation when the null signal is input. We use a bifurcation diagram and FFT analysis to obtain the parameter dependence of the output state and noise characteristic, respectively. The output status of the chaotic double loop delta sigma modulation can be guessed from a bifurcation diagram with the brute force method. We also investigate the noise characteristic of the output signal of the chaotic modulator with FFT analysis and classify the various noise characteristics by changing the integrator gains of the double loop delta sigma modulator. We use FFT and the bifurcation diagram to classify these noise characteristics into three categories: suppressed tone (affected by the chaos), divergence, and the appearance of the limit cycle oscillation. We also confirm the existence of an unusual noise-shaping characteristic caused by the intermittent chaos.

This paper gives a review on the methodologies of using the continuous power spectrum feature of chaos to suppress electromagnetic interference (EMI), which have been extensively studied in the past 15 years, and their practical applications in power electronic converters of various topologies and powers, which have been widely employed in various electrical and electronic devices in our daily lives and thus form the main sources of EMI. This paper not only points out that chaotic modulation is effective and feasible in improving the electromagnetic compatibility (EMC) of various types of power electronic converters, but also gives the circuit design methodologies for different kinds of converters, especially the design methods of modules and chips. It can serve as a guide for engineering applications.