Reciprocity Calibration Of Underwater Acoustic Transducer In A Reverberation Field

The calibration of underwater acoustic transducer is an important research work in underwater acoustic measurement.Calibration method as a measurement method of acoustic measurement is widely used.It becomes increasingly difficult to achieve more low frequency underwater acoustic transducer measurement in finite size pool.The current widespread use of acoustic transducer calibration is free field calibration method in the GB.It has the advantages of convenient operation,mature technology,but due to the calibration frequency affected by factors such as the size of the pool,low frequency or difficult to break the lower limit.Low frequency limit is still very difficult to break through.Reverberation pool is another important experimental facility in underwater acoustic laboratory.In the reverberation pool,the sound waves are reflected at the boundary to form a reverberation sound field.This is widely used in the field of sound power measurement and so on.In the reverberation tank,the reflection of the boundary is separated in time,and the calibration technique is based on the pulse sound.This calibration method is greatly influenced by the size of the pool,which is effective for the high frequency test.The reverberation field can be constructed by using the reflection sound in the reverberation pool,which can be used for the calibration of the underwater acoustic transducer.Based on the reverberation field,research method to carry out the calibration of underwater transducer.The advantage of the calibration of reverberation field is that it can reduce the frequency of calibration limit in the limited space,the operation is simple and quick,and the calibration of multiple hydrophone can be carried out simultaneously,so as to save the cost and improve the working efficiency.The main work of this paper will be derived from the theoretical derivation and simulation method to analyze the characteristics of the sound field in an ideal reverberation tank,study of sound field distribution.According to the boundary condition of the actual tank,the measurement frequency range of calibration test is determined,and the content of the calibration is measured.The reverberation time and reverberation radius are measured.The second study of reverberation field reciprocity theory,put forward the methods of calculation and measurement of reciprocity constant: reverberation time and comparative law,and then the reverberation pool space average method is adopted to improve the method of calibration.The transmitting transducer and receiving transducer space average in the area of the reverberation,get the corresponding electrical parameters,and then calculated for the reciprocity of transducer and receiving sensitivity of hydrophone under test.Finally,according to the measurement conditions and measurement procedures,to form a complete set of reverberation field acoustic transducer calibration method and calibration of a group of underwater acoustic transducer in three different sizes of the reverberation pool,was measured by continuous sinusoidal signals and broadband white noise signal,and the calibration results were compared with the free field calibration results,and the uncertainty is analyzed.The results showed that: compared with the free field calibration method,the calibration method of reverberation frequency is lower;in the calibration frequency range,the reverberation field calibration results and free field calibration results error is less than d B,with the increase of frequency,the error is smaller.Uncertainty of A class is not more than ±0.17 dB,B class uncertainty is not more than±0.47 dB,the synthetic uncertainty is 0.5dB.To verify the feasibility and accuracy of field calibration of reverberation acoustic transducer.