The Application Research On DSP System In Vehicle Flow Detector

Intelligent Traffic System (ITS) is a key aspect of urban planning. The vehicle flow detector is a very import part in the system, and it has been changed from a single contact loop to a mixed non-contact mode. Vehicle flow detection radar system as one of accesses for road information will have broad application prospects in ITS .The Whole system conists: radar, cutting intermediate frequency circuit board, digital signal circuit board and computer operation interface. This paper mainly studies the end part of vehicle flow detector (digital part), focused on how to using DSP chip to realize the principles and methods of vehicle flow detecting with the radar signal. This paper analysis the work principle of radar: FMCW(Frequency Modulated Continuous Wave) , introduces the characteristics and development platform of TMS320VC5416 from Texas Instruments Company, then an application of the digital signal processor in this radar sigal processing is presented in this paper. We designed the digital circuit board of Microwave vehicle detector based on TMS320VC5416 to fulfill the requirement of ITS. Finally, the data got from experiment is compared and analysed and summary and prospects of system is presented.The digital circuit board of Microwave vehicle detector mainly consists the following modules: Power management module circuits, it provides DC power supply for various devices; Clock generating circuits, it generate DSP core clock; The AD converter circuit, it is continuously sampling the IF signal and changing analog signals to digital signals; The DSP module, it executes radar signal processing algorithms, also contrals other related devices, communicates with PC; Memory module, it uses two NOR Flash, The one is used to store code of traffic flow detecting, the code will be loaded to RAM by bootloader program in ROM when the system is powered then excuted in RAM of DSP , the other is used to store data of traffic information; Serial communication circuit, it is responsible for changing parallel data to serial data and communicate with computer; Triangular wave circuit, triangular wave is created by McBSP of DSP and a serial DAC,and it is sent to VCO(Voltage Controlled Oscillator); RTC circuit, which is used to record real-time; CPLD is used to achieve circuit logic contral.The software is developed under the Integrated Development Environment CCS2, which aimed at the Ti's TMS320 Debug Interface standards, Software realizes main process as follows: collect and store IF signal, that is, put sampled data from ADC into RAM of DSP chip; After a certain amount of data is collected, using fast Fourier transform to have spectrum analysis,and using adaptive thresholding algorithm to calculate thresholds; then get statistic result about vehicle flow information according to the theory and experience of vehicle flow.