| With the development of electronic communication technology and computer technology, our meter (including the meter, water meter, and gas meter) copying, charges and management is toward centralization, automation, remote-oriented direction. Currently the modern management level of New Residential Quarter in city has improved continuously, residential customers meter, water meter, gas meter and other meter installation that is achieved in the centralized management, and has data communication interface, to facilitate centralized data collection. Present mainly in support of GPRS/CDMA network equipment to complete the centralized collection, and through public networks and the main station management system data exchange. But meter installation of most common housing residents, especially the rural residents'users with the characteristics of scattered, for this kind of user to use centralized collection equipment such as GPRS or CDMA costs are too high. For these users, we need to develop a new meter collection system. This dissertation focuses on meter-reading system based on the three layers framework, a short distance wireless communication technology-based, combining a variety of means of communication, with covered a wide range, easy to use, save manpower, remote monitoring, remote maintenance features.The whole system consists of main station software and remote meter-reading device. The main station software remote control the users'terminals, editing and distributing the collecting or load plan, receiving the alert data of the terminals, to achieve power loss, cable loss, consumption statistics and a variety of comprehensive statistical analysis of data. The system of remote terminal unit includes collector and concentrator. Installed in scene, the collectors collects monitors and manage the users' power meters at real time followed by the commands of main station software. Concentrator will achieve more than the data collector Collecting, operation management, tasks issued, parameter setting and other functions, generally installed in the center of multiple collector. The means of communication between concentrators and collectors is micro-power wireless, concentrator with the main station to communicate with wireless public network. This paper discusses the design and implementation of low-voltage wireless meter reading system, specifically including the main station software design and terminal hardware design, and highlights the terminal software design.In a network composed of many collectors and one concentrator, their communication through the micro-power wireless. The quality of communication between the devices is different from the actual operation of the wireless network there are various possible complicated situations, affected by operation environment such as housing, trees, buildings, jamming equipment and other factors, not all of collector communicates directly with concentrator. The collector farther from the concentrator or interference, signal loss of the larger collector must pass the other collector that closer to concentrator as a communications relay equipment. In order to improve the system stability and reliability, the system uses a variety of advanced technology to solve the problem of wireless communications. Include wireless module frequency compensation technique, frequency hopping, long data processing system, network adaptation, establishment and maintenance of automatic relay table, automatic processing of the source of interference and other technical means, which in the present system is similar to other more advanced of Key issues specified below:●Data unpacking mechanismInterference problems for wireless communications and the loss problems of long data packets, automatic way to deal with sub-frame. The length packets split into a number of short data packets, and then click to send, receive data packets for the completion of the combination, the composition of the full length data.●Network adaptiveAccording to different wireless network signal strength, the data packet sent to allow the maximum length can be different. Concentrator can be automatically tested under the current situation, identify the data to send the highest stability, lowest error rate, the appropriate data length of the network automatically adapted to local conditions.●Automatic creation of relayWireless communications, for the collectors farther from concentrators and communications is not easy to reach must be relay through the other collectors. How to find each collector to reach the concentrator multiple communication paths, and get an optimal path? According to the actual condition, this paper puts forward a feasible route layered recursive search algorithms to solve this problem. Collecting data in the routine maintenance when the relay table updated to ensure that all other than equipment failure outside the collector may communicate normally●InterferenceLead to poor quality of wireless communication, an important reason for the bit error rate is wireless interference from other devices. When a concentrator work, if. surrounded by other concentrator or wireless device with the same frequency at the same time to work, often the consequence of two devices can not communicate normally. So the question for the interference needs to undertake handling. System of this kind of problem mainly adopts frequency hopping to avoid the interference source frequency.●Flash read and write balancedMeter reading terminal embedded platform, using the Flash chips for data storage, because this system concentrator capacity of the chips that store only 4M, but the amount of data you need to store very much, and therefore this paper a dynamic space allocation scheme to achieve more Flash on small optimized storage. In addition, for a limited number of Flash erase, prone to bad blocks and other issues, we also present the idea of intermediate components to achieve a balanced and effective for Flash read and write bad block management.In this paper, concentrator, collector's software design methods discussed in detail. The main station software made a general description. In this paper put forwards effective solutions for the wireless communication terminal technical and difficult problems, large amounts of data storage efficiency. Finally for the current number of popular computer software technology in the low-voltage wireless meter reading system was discussed. |
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