Research & Implement Of Military Second Order Time-clock

The network synchronization is one of the key technologies for digital communication and the clock is the most important equipment in the network synchronization. Nowadays the demand for steady clock is becoming more and more exigent, especially in military communication system. This paper bring forward a new second order time-clock implement project, and do much in the design of the clock PLL. We try our best to provide the communication equipments that are well-work, easy mobile and contingency in wartime. The main work of this dissertation is as follows:Firstly, we introduce the basic knowledge of network synchronization technology and the clock's important status in the communication system. Then we explain the performance target of the clock and the demand for every order clock.Secondly, we show the basic structure and the principle of the PLL. Then we analyze the old fashion clock system and find out its problem, especially in the military communication clock system.Thirdly, to satisfy the demand of the military communication, this paper proposes a new project that separates the hardware from the software. In this project, most of the clock function is implemented in the CPLD, which reduce the clock depender on the micro-CPU. Moreover, through using more than one clock board at the same time, we increase the reliability of the clock system.Fourthly, in the PLL project, this paper use double loops instead of simple loop. One is used for catching the benchmark frequency and the other adjust the phase in the track state. The double loops project makes the clock working better than before, especially in the track state.Fifthly, we analyze the working performance of the novelty PLL. In this part, we pay much attention to corresponding of the two loops. This novel PLL has narrow band. And it is a loose coupling one. After testing, we get a conclusion the newly clock has satisfied the demands of the military second order clock.