Research On Distributed Radar Based Onmicrowave Photonics Technology

Distributed radar is an important development direction of the future radar, since it can effectively improve the survivability and operational performance of the radar system. Distributed radar using multi-base form has widely distributed transmitters and receivers in the detection zone and obtains the target information by jointly processing the received data at the data processing center. The highly precise position requirement of distributed radar gives rise to several challenges, which include highly reliable distributed system architecture, highly precise time synchronization of multiple stations, generation of large bandwidth orthogonal waveforms and the long distance transmission of broadband signals from multiple stations. Microwave photonics technology can forcefully support the development of distributed radar, since it can overcome the electronic bottleneck of traditional microwave systems in processing speed and transmission bandwidth. It also has the advantages of low loss and immunity to electromagnetic interference.The research direction of this paper is the microwave photonics technology based distributed radar system, and new photonics-assisted methods were proposed in distributed radar system and its key technology. The main research contents of this paper include the following two aspects:1. The wavelength-division multiplexing(WDM) technology based distributed signal source localization system was proposed. Highly precise position of the signal source was realized by introducing WDM technology and radio-over-fiber technology based novel distributed multi-station time difference of arrival(TDOA) localization system architecture.The principle of the TDOA localization technology was analyzed. The impacts of the errors of the estimated TDOAs and the length of the baseline were also investigated. The experimental system consisting of three sensor nodes was built, and an experiment for two-dimensional localization of a wireless fidelity signal source was demonstrated. Location accuracy of 16.21 cm was achieved.2. The WDM technology based multiple-input multiple-output chaotic radar was proposed. Highly precise position of the target was realized by introducing the photonics-assisted generation of wideband orthogonal waveforms and combining it seamlessly with the WDM technology based radio-over-fiber system.The chaotic signal generation based on optoelectronic oscillator was realized and the properties of the chaotic signals were experimentally studied. The impacts of the errors of the estimated time of arrivals and the length of the baseline were also investigated. The experimental system consisting of two transmitters and two receivers was built, and the direct signal suppression was realized based on adaptive filtering. An experiment for two-dimensional localization of a metal target was demonstrated, and location accuracy of 6.49 cm was achieved.