Microwave Chaotic Circuit And Its Applications In Ranging Technology

In the ranging technology, wideband chaotic signal possess the advantages of high precision and good antijamming property for its broad spectrum, noise-like waveforms, and delt-like correlation properties. There have been two main methods of wideband chaotic signal generation:photonics or electronic technologies. However, these photonics-based methods are so costly, incompact, and sensitive to environmental fluctuations, which are not suitable for widely application in the ranging detection. Electronic chaotic systems can overcome these shortages above and thus more desirable in practice.Focusing on the research project of microwave chaotic circuit and its applications in ranging technology, this thesis is mainly summarized in the following:1. Numerical study of the principle and the dependence of chaotic oscillation on the circuit parameters are presented, which build the theoretical basis for designing the microwave chaotic circuit. 2. We implement the generation of chaos in a classical Colpitts chaotic oscillator. And Chaos with different fundamental frequencies are observed. Moreover, By tuning of the supply voltages, we observe a series of complex nonlinear dynamics.3. We report an experimental study of the ultrahigh frequency chaotic dynamics in an improved Colpitts oscillator. Reliable and reproducible chaos can be generated at the fundamental frequency up to2GHz using two types of broadband bipolar junction transistors, namely BFG520XR and BFG425W. Furthermore, we experimentally and numerically study the nonlinear dynamical characteristics of the circuit. The bifurcations diagram and some of the typical dynamic states are obtained. The simulation results are consistent well with the experimental results.4. Experimental study of the testing wire fault using electronic chaotic signal is performed. Using chaotic signal generated by the Colpitts oscillator as a probe signal, and the correlation technique as measurement method, we achieve detection of the cable faults such as open circuit, impedance mismatch and real damage. We also demonstrate the ability for testing live cable using this method. Background noise of the measure correlation trace is compressed by using the average method and discrete elimination method, and the signal to noise ratio is improved.5. A novel chaotic radar system based on improved Colpitts oscillator is proposed and studied. By using the chaotic signal as the probe signal, and correlation technique as the measurement method, we achieve a8cm range resolution and a7.3m detection range.