Field Calibration Device Design And Calibration Method Research Of Acoustic Doppler Current Profiler

Acoustic Doppler Current Profiler(ADCP)is currently the most effective instrument for measuring the flow velocity of multi-layer profiles at home and abroad.It is widely used in marine surveys and hydrological monitoring.At present,the technical indicators of commercial ADCP products are often the test results in a specific experimental environment,and most ADCPs need to work in a more complex environment on site and are difficult to disassemble.At present,the measurement and calibration procedures for ADCP need to be carried out under the harsh environmental conditions of the Laboratory,and there is no field calibration method in use of ADCP,and the accuracy and reliability of ADCP in long-term field environment cannot be guaranteed.This paper introduces the development status of ADCP and its calibration technology at home and abroad.According to the principle of ADCP flow measurement,in order to solve the problem of ADCP field calibration,this paper proposes an field calibration method of ADCP flow velocity based on frequency offset response.Signal transponder,set the delay and frequency offset of the returned signal relative to the transmitted signal to achieve the simulation of the depth of the water layer and the velocity vector,and perform frequency calibration on the signal transmitted by ADCP and the frequency offset signal returned by the transponder,using the frequency Realize the traceability of the value,and then achieve the measurement calibration of the flow velocity.An ADCP field calibration device was developed,including an acoustic receiving sensor array,a cage support,and a test hardware platform.The calibration software program was written and debugged,and a field calibration system was constructed.The ADCP flow velocity calibration experiment was performed in the laboratory muffler pool environment.The source of the error in the flow velocity calibration process was analyzed,and conducted an uncertainty analysis.The results show that the uncertainty of the device in the calibration of flow velocity is better than 3‰×flow velocity value+0.005m/s,which verifies the feasibility of this calibration method.The near-field acoustic holography algorithm was used to calibrate the directivity of a single beam,and then the angles of the four beams were calibrated,and the uncertainty analysis was performed.