Errors Improvement Of Laser Rangefinder Based On TDC-GP2

The laser does not exist in the nature world. When subject to a certain excitation, wecould get laser light.Laser have good directivity, high brightness. Laser distancemeasuring system use laser as the light source, emits a laser beam toward the target, thena photoelectric receiving circuit receives and processes the signal reflected from thetarget, by calculating the laser emission, diffusion, returns, receiving flight time we couldget the distance.This paper introduces the working principle of laser ranging system. Phase laserranging and pulsed laser ranging are the most commonly used.Phase laser ranging systemhas high precision, but it is not appropriate for long distance measurement;Pulse laserrange system could measure a long distance, but the accuracy is relatively low. The finalpurpose of this paper is to improve the measurement accuracy of the pulse laser rangingsystem, so that the range and precision can satisfy more applications.To solve this problem, this paper makes a detailed analysis on the pulsed laserranging system. The errors of the pulse laser ranging system comes mainly from thefollowing two aspects. The time discrimination accuracy and the precision of timeinterval measurement. The change of external environment and some other interferencemake the amplitude of echo signal instability. That will ultimately affect the accuracy oftime discrimination system. There are some time discrimination methods, the frontmoment discriminant method, the zero moment method and a constant ratio method.There has a detailed explanation about the advantages and disadvantages of variousdiscriminant method in the part of the body. Many factors would affect the time intervalmeasurement accuracy,such as counter clock frequency, quantization error andfrequency stability of crystal oscillator. This paper introduces four kind of timing method,the direct count method, interval extension method, time to amplitude conversion methodand time to digital conversion method.Through this comprehensive analysis, the paper research choose the constant ratio moment discriminant method and the high precision timing chip TDC-GP2based on timeto digital conversion.Control of TDC-GP2is done by the micro-controller. Relay on thissystem, then analysis other factors that can effect the measurement accuracy of pulsedlaser ranging system.