Design of Auto Gain Control Circuit with Two-stage Amplification Feedback

设计了一种适用于移动水声通信接收系统的两级放大反馈自动增益控制电路。该电路采用初级放大—滤波—次级放大的信号调理机制,反馈回路同时对两级放大电路进行增益控制,使输出信号稳定在期望值附近,能有效解决移动水声通信中由于收发端相对距离变化、声传播衰减、信道频率选择性衰落、收发端电路频率响应不均匀等因素引起的接收信号时域和频域起伏变化大的问题。海上试验表明:该电路具有良好的幅度均衡性能,能显著提高水声通信质量。An auto gain control(AGC) circuit with two-stage amplification feedback for the receivers of underwater acoustic mobile communication system was presented.The circuit uses the conditioning mechanism of primary amplification—filter—secondary amplification,and the feedback loop controls gains of the two stages amplifiers,making the output signal be stable near the dexpectations so as to effectively solve the problem of signal fluctuation in the time and frequency domains caused by the distance change between transmitter and receiver,sound propagation attenuation,frequency selective fading of underwater acoustics channel and the uneven frequency response of transmitting and receiving circuit.The sea test shows that the circuit has a good performance at amplitude equalization,and can greatly improve the quality of underwater acoustic communication.国家自然科学基金项目(41376040);; 福建省中青年教师教育科研项目(JA15001);; 国家海洋局海洋公益项目(201505027-2

电荷放大器对压电式水声换能器测量的影响分析

为考察电荷放大器对压电式水声换能器测量的影响,通过电荷放大器转换后采集和数据采集卡直接采集的水声声压信号实测实验数据的比对分析,表明受水声换能器线缆的分布电容较大和数据采集卡输入阻抗相对较小等因素影响,数据采集卡直接采集压电式水声换能器信号会对信号的幅值和相位产生影响,且在低频段影响较大,进而给出在各类常见海洋水声应用中的考虑因素和使用建议。中国国家自然科学基金(NO:41676024和41376040);;国家海洋局公共科技研究基金(NO:201505027-2

Application of Multi-channel Sampling and Processing System in Fish Cage Monitoring

深水网箱中的鱼群安全是深水网箱养殖发展中的一个重要问题.提出了一种采用多波束水声换能器(8波束)分区扫描深水网箱对网箱中鱼群分布状态进行实时监测的新方法,设计了一个基于先入先出技术(fIfO)和虚拟仪器技术(lAbVIEW)的多通道数据采集、传输和处理系统,实现了深水网箱鱼群实时监测系统中8个通道回波信号的并行采集和实时处理、深水网箱海上养殖现场与陆地岸站之间的无线数据传输及终端显示等功能.海上现场试验结果表明:系统性能稳定,多通道数据采集与处理系统实时性强、操作使用方便,通过无线数据传输在岸站能实时监测到深水网箱内的鱼群分布和网衣状态,在推广深水网箱养殖安全配套设施上具有广泛的应用前景.Fish security is always an important issue that should be considered throughout the development of offshore aquaculture fish cages.In order to monitor fish activity and distribution in offshore aquaculture fish cage,this paper introduced a novel cage monitoring system which brought forward a new multi-beam(8 beam) divisional acoustic scanning mode to replace of the existing single-beam mechanical scanning mode.Based on the new scanning mode and the techniques of first in first out memory(FIFO) and virtual instrument(LabVIEW software),this system finished 8-channel echo signal processing and sampling,wireless data transmission,real time digital signal processing and image displaying.Comparing with the existing system of mechanical scanning mode,it has a more simplified architecture,an easier power supply and a higher scanning speed.The tests were carried out in the lab and the field of Quanzhou Weitou harbor.Results show that the system has good performance in monitoring the fish activity,distribution and the status of the net cages under different environment condition.国家高技术研究发展计划“863”(2006AA09Z108)专题课题;福建省科技重点项目(2006N0042)资