Research And Design Of The Laser Ranging System Based On The Nios Ii Soft Core Processor

Laser is extensively used in all kinds of field of human living because of the good coherence, direction, and high-brightness, since it was invented in 1960s. Laser rang finding technology is one of the application of laser in military field. Now main laser rang finding methodology include pulse laser rang finding technology, phase laser rang finding technology and some others. With the development and progress of electronic technology, the design methodology of electronic system has greatly changed, and IC is rapidly developing toward high speed, high integration, low power and system integration. The chip design methodology based on SOC and SOPC is becoming the mainstream of electronic system design. Traditional laser range finder is composed of separated cell circuit, which lead to a high cost and complexity. So, laser range finder is developing toward small size and high integration recently.This paper aims to design a full digital integration project of laser range finder, and tries to integrate signal processing unit into a FPGA chip. We use an embedded soft core CPU-NiosⅡ, which is designed by Altera Corporation, and divide the signal processing unit into seven modules: signal processing module based on NiosⅡ, controller module, delay unit module, data memory module, UART communication module based on RS-422, system control signal module and clock signal module. This paper details function and design method of every modules. Compared with the laser range finder composed of separated cell circuit, this project could reduce system cost and size, minish design difficulty, and increase flexibility of system.We also study a number of detection arithmetic of weak laser pulse signals, and design a detection method based on digital FIR filter and correlation detection, which is used to be a solution of low power issue of long distance laser pulse signal. This paper introduces the principle and design method of this arithmetic, and realizes this arithmetic using C language in NiosⅡIDE. Simulation and actual test result shows that the new arithmetic could detect weak laser pulse signal effectively, increase the SNR and expand measuring range of laser range finder.Finally, we have a test of this laser range finding system, explain the experiment result and causation of wrong data, analyze measuring precision and minimum period of laser range finder, and introduce several method to improve the system, which will be helpful for system upgrade in future.