SDH E1固定时隙下的时间信息编解码设计与实现

Design and implementation of time information coding and decoding in SDH E1 fixed time slot

SDH(synchronous digital hierarchy)光纤网络是一种同步复用的光综合信息传送网络。采用SDH E1业务信道构建时间同步系统不仅能够保证时间同步精度,而且具有较好的稳定性。本文设计了一种E1帧在固定时隙中传输时间信息的结构,然后在这种结构下通过FPGA(field programmable gate array)实现了时间信息的HDB3(third order high density bipolar codes)数据编码和解码。本文通过数学模型分析,在E1帧的时间同步信号组合效率上,这种结构比可选择时隙的组合效率高约6.7%。基于E1线路构建的时间同步系统,经实验结果验证,时间同步精度在500ns以内。

SDH(synchronous digital hierarchy)optical fiber network is a synchronous multiplexing optical integrated information transmission network.Using the SDH E1 service channel to build a time synchronization system can not only ensure the time synchronization accuracy,but also have better stability.In this paper we design a structure in which E1 frame transmits time information in fixed time slot,and then realizes HDB3(third order high density bipolar codes)data encoding and decoding of time information through FPGA(field programmable gate array)under this structure.By establishing a mathematical analytic model,the combination efficiency of this structure is about 6.7%higher than that of the selectable time slot in the time synchronization signal of the E1 frame.The constructed time synchronization system based on the E1 line is verified by the experimental results,and the time synchronization accuracy is within 500 ns.