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Application of WLAN in navigation mark telemetry and monitoring system in the Three Gorges Reservoir area of the Yangtze River

Abstract: according to the characteristics of WLAN and its successful application in the field of industrial monitoring, the navigation mark telemetry and monitoring system in the Three Gorges Reservoir area of the Yangtze River adopts the data communication link of wlan+gprs, which effectively solves the data communication problem when the GPRS signal in the reservoir area is weak or no signal. This paper focuses on the group structure, data transmission and main technical parameters of WLAN in telemetry monitoring system

key words: WLAN Untitled Document of telemetry and monitoring application in the Three Gorges Reservoir Area I. application of WLAN in various fields WLAN (wireless local area network) is a solution for fixed wireless access. That is, without using traditional cables, microwave is used as the transmission medium combined with spread spectrum technology to provide users with Ethernet function. It adopts IEEE802.11 standard, provides 1 ~ 11m transmission speed, and has good confidentiality, anti-interference, easy erection and maintenance. It is applicable to the occasions that need to be connected in mobile and roaming between, and provides strong network support in places where it is difficult to wire and nodes that need long-distance data processing. Due to the irreplaceable wireless advantages of WLAN, its technology and products are widely used. In the field of petroleum industry, WLAN wireless connection can provide a data link from the drilling rig to the compressor room; In the financial service industry, JGJ 109 (9) 6 technical regulations for cone rib joints of banks, securities and steel bars. Futures trading businesses can connect institutions through WLAN wireless networks and use handheld communication devices to conduct transactions directly; In terms of hotel management, WLAN can be used to provide timely and considerate services for customers at any time and anywhere. Customers can update the accounting system through the waiter's handheld communication terminal no matter they are carrying out any activities in any place within the region; In particular, gprs+wlan launched by China Mobile makes WLAN more widely used. Various engineering examples provide us with rich practical experience that can be used for reference in the application of WLAN technology in the telemetry and monitoring system of AIDS to navigation. 2、 Overview of the navigation mark telemetry and monitoring system the implementation scope of the navigation mark telemetry and monitoring system in the Three Gorges Reservoir area of the Yangtze River is from the Three Gorges Dam to the bream river section, which is mainly used to monitor and control the operation status of navigation marks and related supporting equipment. The system adopts wireless digital communication technology, satellite positioning technology and computer automatic control technology to realize the remote positioning monitoring and working status monitoring of shore marks and buoys in the channel Remote telemetry monitoring and automatic alarm in case of buoy drift out of range and abnormal working state of beacon light. The system forms a four level network structure of "beacon, station, office and bureau", which realizes the communication coverage of AIDS to navigation and the sharing of resources with the average service life of all aids to navigation data high-speed railway locomotives of about 30 ~ 40 years. Through the implementation of the system, the navigation aids distributed along the Yangtze River will be organically connected with the channel stations, offices and bureaus, so that the management of navigation aids can achieve the goal of "communication modernization, intelligent management, and technological evolution". 3、 Application of WLAN in Telemetry and monitoring system the beacon telemetry and monitoring system is composed of telemetry and monitoring platform, wireless data transmission network and management software (see Figure 1 for details). WLAN is applied to the wireless data transmission network of the telemetry monitoring system, which mainly solves the problem of establishing the communication data transmission chain. Combined with GPRS, WLAN equipment is used as the data transmission relay in the blind area of the public network to form a communication network covering the whole river section, so as to solve the problem of wireless transmission network in the telemetry monitoring system. The following is a brief introduction according to the basic structure of the telemetry monitoring system

Figure 1 structural diagram of Yangtze River Navigation Mark telemetry and monitoring system

1. The function of telemetry and monitoring platform (front-end controller) is to complete the collection of various working information and parameter data of navigation marks. It includes three modules to test the charging voltage and current of solar cells, the power supply voltage of batteries, the light quality and working current of navigation marks, as well as the communication module for data transmission with the land center, namely gprs/wlan. In addition, In order to meet the positioning requirements of the buoy, a GPS single point positioning module is added. 2. The wireless data transmission network mainly solves the data transmission between the telemetry platform and the telemetry monitoring management center. The loss or error of data will lead to the abnormal navigation aids, which requires that the data transmission network must have a high degree of reliability. The Three Gorges Reservoir area of the Yangtze River belongs to the mountainous reach of the upper reaches of the Yangtze River. The economy of the cities and towns along the river is relatively backward, and the construction of communication facilities is not perfect. Through the communication signal test, at present, Unicom has no network signal or unstable network signal in most areas of the upper reaches of the Yangtze River. Only mobile communication can basically cover the channel of the upper reaches of the Yangtze River, but some shore markers are set at a relatively partial position (such as at the foot of high mountains), The mobile public signal may have blind spots or signal instability. In order to meet the goal of stable and reliable communication networks, we have conducted extensive research. At present, there are four kinds of auxiliary networks that can be used, including WLAN, data transmission radio, VHF and wireless data frequency modulation technology (FHSS). According to the actual use of AIDS to navigation power supply (4v200ah), solar power supply and sunshine conditions in the reservoir area, relay communication equipment must have the characteristics of low voltage and low energy consumption. Data transmission radio Very high frequency (VHF) and wireless data frequency modulation technology (FHSS) do not meet the requirements of low voltage and low energy consumption (the voltage of the three devices is 9 ~ 1, with high alignment accuracy of 2V and working current of 1 ~ 2a). Only the working voltage of WLAN device is 4V and the working current can be controlled below 800mA, meeting the requirements of telemetry monitoring system for equipment. The technical scheme of combining wireless private (WLAN) and public (GPRS) is selected to achieve the goal of no blind area in the communication network and ensure the high reliability of the data transmission of the navigation mark telemetry and monitoring system. This kind of network combination has the following advantages: installing WLAN equipment without common signal or with poor signal can achieve the goal of no blind area in the whole network; You don't need to establish your own base station, apply for a dedicated channel, and maintain your network. You can enjoy timely network upgrade. The technology is relatively mature and the power consumption is relatively small. At present, WLAN is widely used in cities, and the equipment and related technologies are relatively mature. Low cost. At the same time, in order to achieve safe and reliable GPRS data transmission, no packet switching occurs

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