用SY87721实现城域网波分复用系统的多业务接入

为了使城域网的DWDM（密集波分复用）系统可以接入多种信号速率和格式，以满足用户的要求，首先介绍了一种波长转换板的设计方法，使用SY87721自适应提取28Mbit／s～2.7Gbit/s之间任意速率信号的时钟，其次介绍了SY87721提取时钟的工作原理、与单片机和CPLD（复杂可编程逻辑器件）的接口方式、对寄存器的配置和读出方式。最后介绍了使用参考时钟测量接入信号频率的方法，这会在系统维护时带来较大的方便。

Realization of Multi-service Connection of the WDM System by Using SY87721

In order to meet user demands of connecting DWDM system with muhi-signal with arbitrary rate, this paper firstly introduces a design concept of wavelength conversion board, which is to use SY87721 clock to get signal adaptively at any speed from 28 Mbit/s to 2.7 Gbit/s of the clock signal. Secondly, it introduces the principles of the clock extraction, the method to connect MCU to CPLD, the register allocation and read out of the modalities. Finally, an introduction to the method of testing the reference clock signal frequency when using the reference clock is also mentioned, which will help a lot to the system maintenance.