The Research Of Time Transfer In Low Voltage Power Line

From the view of time transfer technology, time signal transfer in low voltage power line (LVPL) is studied, and the analysis of channel characteristic, communication technology and protocol, the design of time transfer system, the error control of time signal, and the transmission and distribution of standard time are discussed in detail. The main works can be summarized as follows:1. By the analysis of LVPL's impedance, noise and attenuation, a channel model in low voltage power line is given.2. Based on modern communication technology, linear FM in spectrum is chosen, and linear FM signal transmission characteristic is analyzed. Furthermore, CEBus protocol, which is physics signal transfer standard in power line communication, is discussed.3. A time transfer system in LVPL is designed, and synchronization precision of the system is analyzed. The system can transfer time-code information in short distance (50m) in LVPL, and its synchronization precision is about 5ms. These show that time transfer in very bad power line channel can be realized.4. Transmission protocol and error protocol of data link layer are studied in LVPL. The stability of time transfer system is improved with Tow-State ARQ protocol, dynamic adjusting of link state and code compounding. Simulation results prove: the efficiency of TS-ARQ is prefer to one of stop and wait ARQ protocol.5. The project of standard time transfer and distribution are brought forward in LVPL. Owing to very bad channel of power line and incertitude of other time transfer technology synchronization precision, the project's synchronization precision is about 10ms. The project can be applied to single transformer power supply area.