Design & Implementation Of Data Acquisition System In Digital Imaging Sonar

Underwater acoustic imaging teclmology has played an irreplaceable role inmany situations. Wth wide applying foreground, it has been paid more attention.HoweveY, it is not easy to realize it because of its request for high resolution. Inrecently years digital teclinology has greatly imProved, so it will make great senseto study in digital acoustic imaging system. The purpose of this thesis is to makean attemPt on the aspect.Acquiring high resolution means fOrming narrow and dense beams by use ofhigh-frequence signals. According to normal digital time-delay beamforming, it islinPossible to do that because of its rigorous request in hardware. Digitalinterpolation beamfOrming is feasible. By using it, the result as same as by usinghigh sampling rate can be got after passing a interpolation filter with the premisethat Nyquist Sampling Theorem should be satisfied and the frequence response ofthe filter is good enough. In the thesis digital interpolation beamfOrming isexplained in detail, and the feasibility of acoustic hoaging is demonstrated, too.The working range of acoustic imaging system is short generally. Sofocusing has to be taken into account, or the result will be bad. The above problemis also discussed in the thesis.Higli sPeed multi-channel data acquisition system is a very Anportant part ofthe acoustic imaging system. The thesis has made a research on the design andlinplementation of data acquisition system, which is based on underwater acousticAnaging. The contents include the design of the system struCture, the design ofcircuits of every part, the design of timing as well as the choosing of comPonent.Some problems met during the course of design are also discussed. It has beenproved that in a high-speed system, signal IntCgrity has a great affect on thesystem. Something must be done to solve it.