| Recently reading meter of all kinds of user's meter is basically on the condition of artificial reading meter,it is difficult to guarantee the simultaneous and accurate of reading meter , and characteristics of user's meter is disperse,generous and high building. The work of artificial reading meter is large and inefficient,it not only makes user inconvenient,but also has the appearance of missing reading,mistaking reading,estimating reading.With the development of electronic,computer and communication technology,user and administrative department urgently demand the intervention of modernized management means. That will put forward a new problem for administrative department in the respect of management normalization,automation and charge network,thus it will promote reading meter's electronization,information and network,the task is base on this background,the automatic reading meter of combining low voltage power line carrier with wireless data communicationRemote automatic reading meter system need not personnel go to the user's spot, it combines computer technology with communication technology,network technology and microelectronics technology ,sets up communicate connection through stated network equipments,it has high integration,merge into a whole with software and hardware,automatic rightly collect,transmission,statistics and synthetical analyse for the information of user's real time using amount in all scope and all kinds failure information data.The communicate channel scheme of remote automatic reading meter system include the bottom communicate channel between collecter and sampler and the top communicate channel between management center and collecter. The bottom communicate channel often uses the mode including of infrared ray communication,RS-485 bus,meter bus and low voltage power line carrier communication,etc. The top communicate channel often uses the mode including of telephone line,fibre-optical,wireless and Metropolitan Area Network etc. As the automatic reading meter system's communication scheme will directly affect the reliability of transmission data in all system,we synthesize consider some above schemes in this paper,choose low voltage power line carrier as the bottom communication,use GSM network as the top communication. Because the bottom communication and top communication are the key of all system, we will put stress on this two communication technologies in this paper.Using low voltage power line carrier as the bottom communication channel between collecter and sampler,just low voltage power line composed the most common net because it connects thousands of households. People need not to build other communication channel and provide special radio frequency for it when using power line to transfer data and information. Compared with other communication channel, power line carrier has broader future because it costs less money and less working and can be repaired easily.Power line medium is not suitable for communication. Characteristics of power line medium is first analyzed in this paper. Having researched on signal transmission characteristics of low voltage power line (input impedance,attenuation and disturbance). In this paper,we compare the advantage and disadvantage of power line carrier communication technology using three ways: narrow band communication,Spread Spectrum and OFDM. It is found that OFDM is better if the data transferring rate is high, and Spread Spectrum is more suitable if the data is low. Automatic reading meter system in this paper demands for transferring speed not highly,so we can use spread spectrum to achieve. And we choose a spread spectrum chip—SSC P300 based on it,design modem based on this chip。SSC P300 of Intellon Company in American is a high-performance spread spectrum carrier chip. It uses chirps of scan frequency to make carrier.Power line is a special communication channel,although it adopts modulate,spread spectrum and another technology to strengthen anti-disturb in commu...
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