| Multibeam echo sounder system is a kind of sea bed surveying instruments which can work efficiently and accurately Its development originally bases on single beam echo sounder This kind of system is very suitable for massive sea floor surveying The technique behind multibeam echo sounder system has achieved its maturity with time passage. The main bottom detection technique mainly adopts amplitude detection technique combined with phase detection technique for the mainstreaming multibeam echo sounders, and its use can accomplish ultra-wide coverage for surveying In our country the multibeam echo sounder system gets a late start, and the main technique for sea bottom detection is based on amplitude detection For the theoretical analysis and realization of phase detection method there is no feasible scheme available at present , and it seems that no progress has been achieved This paper presents a systematic research upon the phase difference method for sea bottom detection As a result , detailed technique for fulfilling the sea bottom detection with phase difference method has been given Firstly the author gives a theoretical analysis for phase difference sequence, in order to find the principle behind the phase difference curve The relationship between the acquisition of non-confusion range for phase difference sequence and the zero point location length of the non-confusion range array transducers number, and the angle of array installation has been considered Subsequent tests have been given for the validity and possible applications of the analysis When it comes to estimation of TOA(time of arrival) at given direction, this paper purposes a perpendicular polynomial fit be taken And it also points out that the model for fit should undergo the tests from variance analysis and surplus analysis and repeated experiments Based on those considerations the paper has proved that the phase difference curve is two order for flat sea floor or alternatively one order for rough sea bed Furthermore the paper contends there should be a combination of one and two order fit for actual applications of phase difference With the aid of variance analysis, repeated sea data has been used to compare the effects of WMT method and phase difference method. The claim has been made upon the results that the WMT method should be used in the area near the vertical, while the phase difference method in slant beams And a rule has been given to select among those two methods according to the "effect value" oncondition the depth is knownFor the consideration of improving the measurement precision, this paper studies the factors which affect the TOA measurements, and three expressions of precision has been introducedAs to applications of phase difference method, this paper introduces an automatic hunting method based on amplitude power to get the range of echo arrival . Experimental results show it can find the rough TOA rangeIn order to lessen the computation burden, while getting rid of glints and disturbing components attached to the phase difference signals, the paper suggests a data compression procedure combined with dynamic smoothing . And this processing has been verified by variance analysisIn sea data procession, the WMT method has been used along with phase difference method . The results from the processing of H/HCS-017 multibeam echo sounder data has shown that this combination method can detect a wide horizontal range up to 75 angle to the vertical and obatain the so called ultra-wide coverage detection The precision of measurements has been given under 0.3% generally when surveying angle is under 60?angle in simulation data, while under 0.5% for deep sea detection in the same angle range Therefore this method accomplishes high precision measurements...
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