Lowered acoustic Doppler current profiler with acoustic telemonitoring function

Abstract

The invention relates to a lowered acoustic Doppler current profiler (LADCP) with an acoustic telemonitoring function, wherein, an underwater acoustic communication technology is adopted to transmit the data of depth and height from the bottom of an LADCP suspension system in real time to a water surface control unit by code and decode with code division multiple access for monitoring the positionin water of the suspension system in real time. The lowered acoustic Doppler current profiler comprises an underwater main body part and a water surface telemonitoring part; a master LADCP is internally provided with a communication encoding module, wherein, the master LADCP circularly measures a current profile at fixed time and obtains the height to the bottom according a bottom tracking resultand a depth value by a pressure sensor at the same time; the communication encoding module carries out CDMA code modulation on the height value and the depth value and then outputs the values by a high-speed DA every 1-10s or so, preferably 5s, and emits out the values through a watertight cable and an underwater acoustic communication transmitter; and the underwater acoustic communication transmitter at a water surface telemonitoring part carries out amplification, automatic gain control and filtration on the received signal and then sends the signal to a deck unit through a Kevlar cable.

Description

technical field [0001] The invention relates to an ocean current observation instrument, in particular to a downward acoustic Doppler ocean current profiler with the function of acoustic remote measurement and monitoring. Background technique [0002] The LADCP system is to lower the self-contained ADCP winch from the sea surface to the near bottom at a certain speed, and then lift it from the near bottom to the sea surface. ADCP continuously measures the ocean current profile during the lowering and recovery process, and obtains the entire depth profile after data post-processing The velocity of the ocean current. [0003] In 1989, Eric Firing et al. from the University of Hawaii [Firing, E. and R. Gordon, 1990: Deep oceanacoustic Doppler current profiling. Proc. IEEE Fourth Working Conf. on Current Measurements, Clinton, MD, Current Measurement Technology Committee of the Oceanic Engineering Society , 192-201] first tried to bundle the self-contained ADCP and the Conducti...

AI Technical Summary

Problems solved by technology

[0005]The LADCP system requires the measurement of the absolute flow velocity of the near-seabed current layer relative to the ground. The lifting system hits the bottom, resulting in equipment damage, or even the loss of the entire lifting system; another operational risk of the lifting system is that the lifting system flies out of the water due to unclear current depth of the lifting system during recovery, resulting in "speeding"

Usually, these two problems can be solved by returning the data of depth and height from the bottom by hoisting the cable, but this requires the support of a 10,000-meter cable winch, and many experimental ships do not have such conditions, which limits the application of LADCP

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