The Research Of Doppler Log's Velocity Measurement And Software Design Of Display And Control System

Doppler log is a precise instrument, which is used to measure ship's velocity and accumulate its voyage on the theory of sound wave's Doppler effect. It not only has the advantages of high accuracy velocity measurement,but also can work in shallow water and measure the lower speed. By the emergence of multi-beam system represented by JANUS system,the interference caused by ship's bump and gurgitation can be greatly weakened. The applicantion of phased-array technology makes the problem that compensation of sound's velocity solved in theory,which has greatly improved the performance of the traditional Doppler log. In this thesis,we researched on the design of its display and control system,the study of velocity measurement (frequency measurement) and the analysis of test data in lake.The theory of Doppler log is introduced detailedly and the application of JANUS configure and phased-array technology are researched. We discuss the thought of display and control system of Doppler log,thoroughly expatiate primary function which is implemented by display and control system and the scheme of its workflow; the design of several important function modules such as signal sampling,serial port communication, postpositioned data processing of frequency measurement, velocity's resolution are emphasizely introduced; three common methods of frequency measurement,i.e.zero-crossing detector, complex covariance, self-adapting are contrastively researched theoretically.Finally,in accordance with the test data, we analysis the Doppler log's accuracy of velocity measurement under zero-crossing detector.The test sailing in lake shows that the system is accuracy and reliability and provides an useful inspiration for future.