[[alternative]]The signal analysis and circuit design of Laser Range Finder

碩士機電工程學系[[abstract]]雷射測距包含括相位法、脈衝法以及三角量測法，相位法適用於短距離的量測，脈衝法則用於中長距離的量測。不論是相位法或脈衝法，欲獲得高精度的距離量測，兩者都需要相當高的電路設計技術才能達成。 本實驗中，利用相位式雷射二極體測距法，主要針對相位計的模擬與設計，以及改進先前所設計的測距電路。相位計是用來計算兩相位差而設計，因為發射與接收兩訊號在混頻後會有相位差的產生，經過相位計後再由微處理機計算距離顯示在LCD面板上。 電路設計上以類比訊號處理為主，因為混頻完的訊號太差，即使後端作的再好也是徒勞無功。所以本實驗將先前的電路修改不良的地方以及降低EMI的影響。最後實驗後的電路實現在電路板上，這樣也可減少訊號在電路上的損失以及美觀上也大大改善。[[abstract]]The laser range finder operates in ways: phase-detecting, pulse measuring, and triangulation. The phase-detecting method is suitable to measure short distances and the pulse method is measures middle or long distances. In the past, every method wanted to measure distance□accurately. To reach this goal, all of them have to cooperate 100％. The phase-detecting method is used in our laser diodes range-finder. The experimental simulations we designed the phase meter, and then we improved the design. The phase meter measures phase shift between two phases, during the theorinesare from the emitter and receiver. After all processes, the microprocessor computes the phase shift and shows the distance on the LCD. Circuit design focuses on the processing analogy signal, because quality of the mixed signal is too bad. All the experiments are in vain, even if the MUC has been designed perfectly. For these reasons, we read some reference about circuit design and listen to the professionals’ suggestions. After researching, we redesign the circuit and reduce the EMI. Finally, the circuit converts into a PCB board