Design And Implementation Of High Speed A/D Acquisition And Processing Circuits For Digital Laser Range Finder

Laser range finder refers to a kind of equipment that utilizes laser impulses targeted at objective or continuous wave laser beam to measure distance. Traditional laser range finder usually adopts analog circuit, which is relatively simple but easy to be disturbed by noises, emerge "fake up" or "miss check" phenomena, resulting poor measurement accuracy. Digital laser range finder, on the other hand, by applying digital signal processing technology, can increase anti-jamming capability, and improve range measurement accuracy. The core of digital laser range finder measurement reception circuits is to implement high speed data acquisition and processing.The design of high speed A/D acquisition and processing circuits for digital laser range finder consists of modules such as high speed A/D conversion, FPGA control, data cache as well as DSP process etc. Based on the principle of three pulses range measurement, in order to meet the performance requirement and future function extension, the following design factors should be considered,(1) for A/D conversion rate500MSPS, ADC081000made by National Semiconductor Corporation is selected as the main chip of ADC;(2) for FPGA, Virtex-4series chip XC4VLX40-10FF668I made by XILINX is used and Layered Modular Design is achieved by VHDL language;(3) considering the speed, capacity, cost and implementation complexity, DDR2data cache circuit module is used, and high speed accessing to DDR2is achieved by IP CORE provided by XILINX;(4) for time complexity and flexibility, hybrid FPGA+DSP design is employed to handle the echo signal processing, signal filtering and averaging, discriminant calculation, etc, where the DSP is chosen as ADFs TS101s with working clock frequency200MHz. As the sampling clock frequency of ADC circuit is as high as500MHz which belongs to high-speed circuit, this thesis analyzed the possible problems and challenges in high speed PCB circuit design, including reflections, crosstalk, ground bounce etc. Finally, actually circuit was tested and evaluated. Some perspectives for future development are also presented.