Algorithm Research And Software Implementation Of Microwave Vehicle Detection Based On FMCW Mode

Microwave vehicle detector has many advantages, such as being installed and maintained conveniently, working in all weather, having strong ability of detection and so on. It has broad application prospect.The FMCW mode microwave vehicle detector is chosed as the object to conduct related research on basic principle, system implementation, algorithm design etc. Firstly, the basic theories of FMCW microwave vehicle detection technology, including the ranging principle, the mathematical model of the intermediate frequency signal under the triangle wave modulation in the ideal case, the windowed FFT algorithm, and interferences in the system are expounded. In addition, according to the stationary clutter that may exist in the actual environment, the basic principle of the dual slope triangle wave modulation signal is discussed. Then, the FMCW mode microwave vehicle detector is implemented. IVM-297 sensor is selected as the microwave transceiver module, the circuit of the triangular wave modulation signal is designed based on DDS technology to generate the dual slope triangle wave which can be amplified linearly, and for the reason that the reflection energy of the microwave decay fast with the increasing of distance, the reflected signal of the far lane can be compensated by the circuits. The sampling frequency is set by the FPGA, and to operate efficiency and enhance the scalability of system, the data processing circuit uses FPGA+ ARM mode as its structure, and each circuit module is realized. In addition, the design of Linux drivers for FPGA interface is also discussed.Finally, the intermediate frequency signal processing algorithm based on FMCW mode microwave vehicle detector is studied. In order to display the intermediate frequency signal and its spectrum, and also to set the relevant parameters conveniently, the intermediate frequency signal processing software is developed in the PC end. To analysis the spectrum of the IF signal, windowed FFT operation is used, and the relationship between the IF signal and the target distance and the ranging accurancy of the microwave vehicle detector are verified by the distance detection experiments of single object and multi object. The background subtraction method and maximum spectral peak detection method are used for target detection, the detection threshold settings is discussed. At last, the vehicle classification principle and the methods for experiments are discussed. In summary, the FMCW microwave traffic detector is designed and teseted, the results lay a foundation for further research.