Branch Unit for Seafloor Observatory Network

Abstract

Abstract-One key issue of seafloor observatory network is to ensure that the whole system operates normally when some equipment failure exists. Branch Unit can cut off the connection between the failure parts and the backbone network automatically and protect other equipment of the network from the impact of equipment failure. This paper proposes a design of the Branch Unit. The Branch Unit uses zener diode to provide power for the control circuits and constructs DWDM system with the help of the OADM. One Branch Unit model was built in this paper. Experiments verify the principle and functions of the Branch Unit and prove the feasibility of the design. The design provides a reference for the realization of the seafloor observatory network.Keywords-seafloor obseratory network; Branch Unit; DWDM; zener diode I. INTROUCTIONOceans cover 70 percent of the earth's surface; the seafloor is rich in natural resources such as manganese nodules, hydrothermal sulfide, oil and gas, and natural gas hydrate. Exploration and exploitation of marine resources is very important for human survival and sustainable development [1]. Following the ground/ocean and space, seafloor observatory network becomes the third platform of observing the earth system. The North Eastern Pacific TimeSeries Undersea Networked Experiment (NEPTUNE) and ESONET are two sub-sea networks, which were initiated by the USA and Canada (NEPTUNE) and European Union respectively [2][3]. Seafloor observatory network is gradually becoming a new hot spot in the field of marine science and technology. Compared with foreign countries, seafloor observatory network construction starts relatively late in China. But some important progress in some key technology has yet been made.Seafloor observatory network has broken the constraints of energy and data transmission, and makes that it is possible to obtain long-term, real-time, large range, large amount data observation of the seafloor. Seafloor observatory network adopts the single-stage medium-voltage DC parallel transmission mode and Dense Wavelength Division Multiplexing (DWDM) technology (Figure 1) [4][5]. It has important practical significance to explore how to separate the submarine cable fault in the parallel mode and distinguish the separate and coupling of different wavelength in space. II. THE STRUCTURE OF BRANCH UNITThe seafloor observatory network has two main portions: power supply subsystem and communication subsystem. The power supply portion of the shore station produces medium voltage of 10kV direct current. The power is transmitted to the main Junction Box for underwater sensor device through fiber-optic/power composite cable, the Branch Unit, the branch cable. The communication portion of the shore station adopts DWDM technology that uses Wavelength Division Multiplex (WDM) to composite different wavelengths into the same fiber to achieve communication with the subsea sensors. The main portion of the repeater is Erbium Doped Fiber Amplifier (EDFA) [6], which is used to enlarge the transmission optica...