基于信号重采样频移处理的宽带ADCP分层校准方法

Calibration of broadband ADCP for multi-cell based on frequencyshift processing by signal resampling

针对宽带声学多普勒流速剖面仪(ADCP)现有校准方法无法有效实现流速分层校准的问题,提出基于信号重采样频移处理的声波应答校准方法,通过应答换能器组分别接收ADCP各波束换能器发射信号,经分段重采样、时间窗补偿等处理,产生包含多普勒频移信息的模拟回波信号,实现对宽带ADCP流速分层校准。为更符合真实水体散射情况,基于主动声呐方程建立了回波信号幅度计算模型。搭建了可适用于陆上和水下的宽带ADCP分层快速校准装置,对两个ADCP样机开展了校准实验,流速范围在0.01~10 m/s,测量不确定度优于0.3%v+5 mm/s(v为流速测量值)(k=2),并与水槽拖车法进行了对比验证。

The current calibration methods of broadband ADCP cannot effectively realize the measurement of flow rate stratification.An acoustic response calibration method based on frequency shift processing by signal resampling is proposed in this paper.This method utilizes a group of response transducers to receive the signals transmitted by each transducer of the ADCP to be calibrated,then some simulated echo signals which contain Doppler shift information are generated by the process of signal segmentation and time-window compensation.In order to be consistent with the real water scattering situation,a calculation model of the echo signal amplitude is given based on the active sonar equation.A broadband ADCP calibration system for multi-cell is established,which could be applied in on-land and underwater,and two ADCP devices are calibrated by designing some experiments.The measurement uncertainty of the calibration system is less than 0.3%v+5 mm/s(v denotes the flow velocity)(k=2)in the flow velocity range of 0.01~10 m/s.The proposed method and calibration system are also verified by comparing to the flume towing method through experiment.