Measurement Method of Sound Velocity Based on Seabed Sediment

Abstract

The invention relates to an acoustic velocity measurement method based on marine bottom sediment. The method is mainly technically characterized in that a sediment sample tube is placed on a transmitting transducer support, a precision ball screw drives a linear slider to perpendicularly move through a crank handle, so that a receiving transducer is contacted with the top of the sediment sample tube, and a signal processing module calculates the actual distance between a transmitting transducer and the receiving transducer according to a count value measured by a distance measuring sensor; the signal processing module calculates a waveform time delay truth value of the receiving transducer and the transmitting transducer with a time delay measuring method of double-frequency CW (clockwise) pulse; and an acoustic velocity of the marine bottom sediment is calculated through a relation that the acoustic velocity is equal to a quotient obtained by dividing the distance by the time. According to the acoustic velocity measurement method based on marine bottom sediment, the sediment sample tube is placed between the receiving transducer and the transmitting transducer, the distance between the receiving transducer and the transmitting transducer is measured by the distance measuring sensor, the acoustic velocity of the marine bottom sediment is measured with the signal time delay measuring method of double-frequency CW pulse, higher time delay measuring accuracy is achieved, and an automatic detection function is realized.

Description

technical field [0001] The invention belongs to the technical field of sound velocity measurement, in particular to a sound velocity measurement method based on seabed sediments. Background technique [0002] At present, there are mainly the following two measuring devices for sound velocity measurement of seabed sediments: one is a sound velocity measurement device constructed by the State Oceanic The School of Mechanical and Electrical Engineering of the Industrial University and the South China Sea Institute of Oceanology of the Chinese Academy of Sciences jointly developed a sound velocity measurement device for seabed sediments based on an acoustic wave probe. The above two sound velocity measuring devices are described respectively below: [0003] The sound velocity measurement device built with WSD-3 digital acoustic wave instrument adopts the time delay estimation method of pulse front detection. The frequencies of the transmitting transducers are 25kHz, 50kHz, 100...

AI Technical Summary

Problems solved by technology

The advantages of this measuring device are: the sample length is large, the precision requirements for the length measuring device are low, and the structure is simple; the disadvantages of the measuring device are: the transducer is small, the working frequency is low, the sample length is too large, and the measurement result is that each layer of sediment Combined results of sound velocity, affecting measurements

The disadvantages of this measurement device are: low sensitivity of the acoustic wave probe, additional disturbance to the sample; low frequency, complex sound field in the medium

[0005] In summary, the existing seabed sediment sound velocity measurement device mainly has the following problems: (1) the planar emission transducer is adopted, but the relationship between the acoustic frequency, the emission beam width and the sample size is not considered; the emission beam The width is generally too large relative to the sample size, and the sound wave is reflected at the sample boundary, resulting in disordered received waveforms

(2) The time delay estimation adopts the method of detecting the arrival time of the first wave. On the one hand, due to the influence of the system bandwidth and phase shift, the first wave is easily missed, resulting in errors in time delay measurement; on the other hand, the detection of the first wave Mainly rely on human observation, it is difficult to realize automatic detection

(3) Since the manufacturing process of special-shaped transducers in China is still not very mature, the price and performance of special-shaped transducers still cannot meet practical needs

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