Research Of Laser Phase Method Ranging Based On Cpld

Along with the rapid development of technology in the fields of semiconductor laser, optical detection and integrated circuits, which promote constantly the laser range fmder towards miniaturization, automation and digitization. As the phase-shift laser range finder has the characteristics of high precision, high speed, low cost and suitable for measurements in the short-range, it has been widely used in the areas such as military, aviation and industry.In this thesis, the basic principle of phase-shift laser range-finding is discussed. Based on the dual-scale measurement and differential frequency phase measurement, a laser ranging system which uses CPLD (Complex Programmable Logic Device) is designed. Moreover, the hardware circuit and the software program of the system are implemented.The hardware circuit includes frequency integrated circuit, laser modulation transmitter circuit, photoelectric detection circuit, filter and amplifier circuit, the waveform shaping circuit, the CPLD circuit and the Single Chip Microcomputer circuit. Among them, the advanced technology of DDS (Direct Digital Frequency Synthesizer) is used in frequency integrated circuit. The frequency generated has the feature of stability, high resolution and fast switching. In the optical receiving system, fine-scale-frequency signal and coarse-scale-frequency signal are amplified and shaped by the same set of circuit. It simplifies complexity of the system and reduces the cost. The differential frequency module and automatic digital phase discriminator are designed in CPLD. Combined with the previous research, for the traditional phase discriminator, a method is proposed to improve its stability. Then, the value of the phase discriminator is sent to the Single Chip Microcomputer. The Single Chip Microcomputer is the control core of the system, and it plays the role of controlling the DDS chip, driving the phase discriminator in CPLD, progressing data from phase discriminator and displaying the results of ranging.Each circuit module, which has been debugged, achieves good result and basically satisfies the request of the design. Finally, the inadequacies of the system have been analyzed, and the appropriate improving ways have been given.