# Deep-Sea Underwater Cooperative Operation of
## 4 Support System  
Underwater wireless communication is crucial to ensure the interconnection of underwater manned/unmanned submersibles and surface vehicles. Although the underwater wireless optical communication can achieve high-speed communication, the transmission distance is short, usually only a few hundred meters. As it is difficult for electromagnetic waves to propagate through seawater, underwater acoustic communication is the only solution for long-distance underwater wireless communication. Four communication methods are integrated for the UACS to meet different needs: (1) coherent underwater acoustic communication, with a variable transmission rate from 5 to 15 kbps, to transmit images; (2) non-coherent underwater acoustic communication, with a transmission rate of 300 bps, to transmit texts, instructions, and sensor data; (3) spread spectrum underwater communication, with a transmission rate of 16 bps, to transmit instructions; and (4) underwater voice communication, using single sideband modulation, to transmit human voice. Coherent, non-coherent, and spread spectrum underwater acoustic communications are forms of digital communication, while underwater voice communication is a form of analog communication. Furthermore, the transmission distance of conventional radio communication is limited due to the curvature of the earth. The communication between the USV and the research vessel R/V mainly relies on the communication satellites in the sky. To complete the three cooperative operational modes, the research vessel R/V, USVs, lander, and HOVs need to be installed or equipped with a complete cooperative operational command and monitoring system. This can realize on-site information summarization, real-time data display, and command output and data storage of underwater cooperative operation through the integration of water surface monitoring, underwater acoustic communication, and underwater navigation and positioning. In this way, it provides decision support for the on-site commander and forms a complete on-site command and monitoring system for the cooperative operation of manned and unmanned submersibles. Figure 10 illustrates the schematic diagram of the cooperative operational command and monitoring system. It is installed on the research vessel R/V and can receive data from the shipboard integrated positioning sonar, shipboard compass, shipboard GNSS, UACS, shipboard video server, and other equipment. The cooperative operational command and monitoring system is connected to the research vessel R/V's area network, and the water surface monitoring server provides services for the whole research vessel R/V network. It can receive data from the USBL server, UACS server, GNSS signal, satellite communication signal, and the gyro sensor from onboard networks. These data are integrated and displayed externally by the surface monitoring display matrix, which can be used and analyzed by the surface commanders. When manned and unmanned submersibles work together underwater, the command and monitoring system plays the role of providing a map display and data support for surface commanders. The hardware part of the cooperative operational command and monitoring system includes the water surface control box and the water surface integrated display and controller matrix. The water surface control box is the core unit of the water surface monitoring unit. As the operating carrier of the water surface monitoring software, it is responsible for comprehensive processing of multi-source data, such as shipborne, underwater acoustic, position indication, and satellite communication data. The surface integrated display matrix is responsible for visually displaying the integrated information of the submersibles and the research vessel R/V. The surface monitoring software collects the data provided by the research vessel R/V through the research vessel R/V area network, such as GNSS, USBL, and gyro data.