The Simulated Research Of Real-time Laser Short Range Finding Based On FPGA

The thesis is based on the project of Real-time laser short range finding. Through theoretical analysis and simulation, the main key-technologies of the Real-time laser short range finding are systematically researched. The traditional methods are found unsuitable for real-time short range finding. Doing research on the Real-time laser short range finding technology is very important for both military uses and commercial applications.In the sections of the design theories, the different types of function mechanism of laser fixed distance are contrast studied, we choose the phase shift and identification mode of fixed distance because the inside time delay can be easily compensate, convenient to the digital circuit design and the false alarm rate is low. The design of the transmitting and the receiving system are also discussed, in the receiving system we design a circuit of two AD603 cascaded achieved AGC to meet the small volume, low-power design requirements. At the same time the anti-jamming of the system are also discussed.The other main work of the thesis is the design of digital signal processor. The frequency of the counting clock in the processor is the main factors of precision. It is also the difficult and important point of the design. The processor use the internal PLL module of FPGA to make the frequency multiplication as the basic clock, we get the high frequency clock under the premise of not changing basic clock by the same frequency four-phase counting method. At the same time it also can increase the precision of the system. The subject demands of the 0.5m-1.5m from the scope, 0.2m from the precision, the equivalent clock frequency is greater than 1.5GHz, so we select Altera's Cyclone FPGA-EP1C6 series, finally the equivalent clock frequency is 1.6GHz, the precision less than 0.1m. The whole circuit system is in the internal FPGA with VHDL language programming, does not need extra to increase system's cost and the volume.At last, in QuartusII environment, the producing process of phase difference signals,the producing process of high frequency clock,the function of the whole system and the measurement error have been simulated, the result of the simulation coincides the signal processing system can fix distance at the setting distance, and the precision is high. The result also has proved the correctness and feasibility of the design.