深海走航抛弃式测量仪器时变信道对传输性能的影响

由于环境的要求,深海走航抛弃式测量仪器信号传输大多使用有线信道,然而,信道的电阻抗随放线长度不断变化,严重影响了深海走航抛弃式测量仪器信道传输的稳定性.本文以国家海洋技术中心自主研发的走航抛弃式温度、盐度、湿度(XCTD)剖面仪的传输信道为原型,提出了一种动态分析有线信道对传输信号幅值和相位影响的方法.首先推导出各电路参数随信道长度变化的规律,建立简化的传输电路模型和该模型的传输函数.通过定性分析得出传输频率、分布电容和缠绕电感对信号相位的影响.利用MATLAB软件分析XCTD在动态放线过程中信道对信号幅值和相位的影响.研究结果可进一步指导抛弃式走航测量系统的电路设计,提高测量数据的精度和信号传输的稳定性.

Analysis of time-varying channel effects on transmission performance of deep-sea abandoned measuring instrument

Because of the environmental requirements, deep-sea abandoned measuring instrument mostly uses the cable channel. However, the stability of the channel transmission is seriously affected by length change in electrical impedance of the channel. In this paper, a new method is presented, which is used for dynamically analysing the effects of the cable channel on the amplitude and phase of the transmission signal by using XCTD (expendable conductivity, temperature and depth) profiler transmission channel. Firstly, regulations about the parameters of each circuit varying with the channel length is proposed. Meanwhile, the simplified transmission circuit model and its transfer function are established. Through qualitative analysis we can conclude that the transmission frequency, distributed capacitance and winding inductance have an influence on the signal phase. Finally, in this paper we analyse and discusse how the cable influences the transmission of signal, and present the reason of the influences with MATLAB, which can further guide the design of the XCTD measuring system and improve the accuracy of the measurements and the stability of signal transmission.