A Laser Ranging System

With the improvement of economic level and the accelerating rhythm of life, the efficiency and accuracy of instruments gradually become the core issues. The technology of measuring distance plays a pivotal role in surveying and mapping, auto reversing system, construction industry etc., and this technology will be more and more important due to people’s pursuit of high quality of life. In this case, it’s necessary to develop a long-distance and highly precise rangefinder without contacting to replace the traditional inefficient method. Based on the basis of this, the thesis combined with the theory of photoelectric technology, direct digital synthesizer, mixing, high-speed sampling, fast Fourier transform technique etc. and successfully designed a laser ranging system.Firstly, the thesis analyze the principle of laser ranging, then compares the advantages and disadvantages of various measuring principle. Finally, it selects the principle of phase measuring based on FFT spectrum analysis to realize the scheme of distance measurement and provides the system block diagram. After highlighting the characteristics and working principle of different lasers, the thesis details the composition of the various parts of the system, moreover it emphatically discusses power module, the driving method of a semi-conductor laser diode, generation of sine wave, frequency mixing module, high-speed sampling module of smallest single-chip system and the core hardware circuit’s principle diagram of the DSP minimal system, the interior structure and operating principle of the main chip of this system.Also, this thesis introduces the communication between MCU and DSP system, generation of sine wave, frequency mixing module, high-speed sampling module, the design diagram of the program which achieves the parts of the software application of FFT on DSP and the code of the main functions. What’s more, it introduces the implementation principle of inter-system communication protocol and the FFT in detail. Finally, the thesis gives part of effect drawings of circuit board and debugging methods of circuit module, provides expected schemes of possible problems in the process of debugging, conjectures ways of improving system performance, and puts forward directions of upgrading system in three aspects, finally gives the debugging result, which shows that the debugging result meets completely requirements and the error can be limited to 2mm.The ranging system this thesis provides has solved the problem of low efficiency, short-stroke and low precision. After the improvement, this system can be used in the fields of topographic mapping, industrial architecture, and automotive electronics. In a word, it has a broad prospect.