投弃式海流电场剖面仪中模拟电路的研制

doi:10.19657/j.geoscience.1000-8527.2022.076

摘要/Abstract

摘要：

投弃式海流电场剖面仪(XCP)是利用海流切割地磁场产生感生电场的原理进行快速测量海流的观测仪器,在地磁场稳定的情况下,感生电场的大小主要取决于海流的速度。因此,通过测量海流产生的感生电场便可以研究海流的运动特征。本文研制了用于XCP中的模拟电路,实现了对XCP中电极信号、罗盘线圈信号及温度信号的采集预处理。所设计模拟电路主要实现以下功能:(1)通过INA128放大电路实现对电极信号与罗盘线圈信号的多级放大处理;(2)考虑到电极信号与罗盘线圈信号均为频率16 Hz左右的信号,在电路中加入中心频率点为16 Hz的二阶带通滤波电路以提取有效信号;(3)进行硬件电路补偿,在一定程度上克服XCP探头下沉引起感生电场的强干扰。实验测试结果表明,所设计模拟电路稳定可靠,可以实现滤除噪声,提取前端微弱信号并进行多级放大,满足实际应用需求。

关键词: 投弃式海流电场剖面仪, 模拟电路研制, 信号采集, 微弱信号

Abstract:

Expendable current profiler (XCP) is an observation instrument for rapid measurement of ocean current based on the principle that ocean current cuts the geomagnetic field to produce induced electric field. When the geomagnetic field is stable, the magnitude of the induced electric field predominantly rests with the velocity of the ocean current. Therefore, the motion characteristics of the current can be explored by measuring the induced electric field originated from the ocean current. In this paper, the analog circuit used in XCP was developed, and the acquisition and preprocessing of electrode signal, compass coil signal and temperature signal in XCP were realized. The main functions of the analog circuit are as follows: (1) the multi-stage amplification of the electrode signal and the coil signal is realized through the INA128 amplification circuit; (2) considering that the frequency of the electrode signal and the coil signal is 16 Hz, a second-order band-pass filter circuit with a central frequency of 16 Hz is added to the circuit to extract the effective signal; (3) compensate hardware circuit is adopted to overcome that strong interference of the induced electric field resulted from the sinking of the XCP probe. The experimental results show that the analog circuit is stable and reliable, and it can filter the noise and extract the front-end weak signal for multi-stage amplification to meet the needs of practical applications.

Key words: expendable current profiler, development of analog circuit, signal acquisition, weak signal

中图分类号:

P631

李鹏宇, 张启升, 周珂宇, 林祖灿, 蒋兴远. 投弃式海流电场剖面仪中模拟电路的研制[J]. 现代地质, 2023, 37(01): 107-113.

LI Pengyu, ZHANG Qisheng, ZHOU Keyu, LIN Zucan, JIANG Xingyuan. Development of the Analog Circuit in Expendable Current Profiler[J]. Geoscience, 2023, 37(01): 107-113.

图/表 11

图1 海水流动方向示意图(据文献[14]修改)

Fig.1 Schematic diagram of the direction of ocean current (modified from ref.[14])

图2 XCP中前端传感器及模拟信号处理部分整体框图

Fig.2 Overall block diagram of front-end sensor and analog signal processing in XCP

图3 减法电路示意图

Fig.3 Schematic diagram of the subtraction circuit

图4 滤波电路示意图

Fig.4 Band-pass filter circuit

图5 模数转换电路原理图

Fig.5 Schematic diagram of analog to digital conversion circuit

图6 5 V电源纹波测试(a) 和-5 V电源纹波测试(b)结果

Fig.6 Results of 5 V power ripple test (a) and -5 V power ripple test (b)

图7 电阻衰减网络

Fig.7 Resistance attenuation circuit

表1 电极通道放大倍数

Table 1 Electrode channel magnification test

电路板编号	信号频率/Hz	衰减电路衰减倍数	电极通道放大倍数
1	16	3766.478343	120527.30
2	16	3735.524841	119462.09
3	16	3769.317753	111209.96
4	16	3732.736096	115752.14
5	16	3756.574005	119083.40
6	16	3769.317753	111209.95

表2 线圈通道放大倍数

Table 2 Coil channel magnification test

电路板编号	信号频率/Hz	线圈通道放大倍数
1	16	2529
2	16	2704
3	16	2655
4	16	2623
5	16	2769
6	16	2600

图8 线圈通道输出波形

Fig.8 Coil channel output waveform

图9 电压比较器测试

Fig.9 Voltage comparator test

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