Zhiguo Shi

Error feedback synchronization of chaotic Colpitts circuit

Synchronization plays an important role in chaotic communications because it offers a potential advantage over noncoherent detection. In this paper we studied the synchronization of two coupled chaotic Colpitts circuits with linear error feedback scheme. The error dynamic system of the two coupled circuits was studied and the nonlinear junction in it was linearized for the sake of simplifying the problem. Based on a generic criterion of global chaos synchronization between two coupled chaotic systems from a unidirectional linear error feedback coupling approach, this paper derived the sufficient conditioner two coupled Colpitts circuits to obtain synchronization. Circuit simulations haw been carried out to verify the results

Compact Dual-Band T-Slot Antenna for 2.4/5 GHz Wireless Applications

In this paper, we present the investigations on a compact dual-band T-slot antenna for 2.4/5 GHz wireless applications. The antenna is composed of two orthogonal slots with a compact size of about 17 mm x 10 mm, which only occupies less than 4% of the ground plane (80 mm x 50 mm, area of a typical PC wireless card). In this way the antenna can be easily integrated in one circuit board with other electric circuits as a whole. To understand the characteristics of the proposed antenna, the influences of different geometric parameters on the antenna resonant frequency is investigated. It is shown by HFSS simulation that the proposed antenna can completely cover both 2.4/5 GHz bands with satisfactory radiation characteristics for 2.4/5 GHz indoor wireless applications.

Single-channel communication scheme based on dual synchronization of chaos

A novel single-channel digital secure communication scheme based on dual synchronization of chaos in Colpitts circuits is proposed. Two binary messages, modulated by the OOK scheme and mixed together with two chaotic waveforms, serve as the only transmission signal through a single channel. Simulation results show that two messages can be successfully recovered at their respective receivers. The proposed scheme shows tremendous advantages in terms of effective utilization of spectrum resource for multi-user communications and potential applications in secret sharing systems.

Synchronizing chaotic Colpitts oscillators pair and Chua's circuits pair simultaneously using one scale signal

In this paper, we show that one pair of Colpitts oscillators and one pair of Chuas circuits can be synchronized simultaneously using one scale signal. The cross coupling method is used, where the voltage difference between the sum of two master oscillators (one Colpitts oscillator and one Chuas circuit) and one slave oscillator is converted to current and then fed into the other slave oscillator. Topics such as how to select the coupling signal and what is necessary for the two different pairs can be synchronized easily are discussed. This synchronization scheme provides a possible way of multiplexing mixed chaotic signals generated by difference electronic oscillators.

Adaptive synchronization of chaotic Colpitts oscillators combating circuit parameters mismatches

In this paper, synchronization of chaotic Colpitts oscillators, using adaptive controllers to combat circuit parameter mismatches, is studied by numerical simulations. Synchronization errors caused by different main circuit elements are compared, and compensation for constant and time-variant circuit parameter mismatches are demonstrated. Simulation results indicate that the synchronization performance of chaotic Colpitts circuits can be greatly improved by applying adaptive controllers when constant or slow time-variant circuit parameter mismatches are considered.