The paper introduces the principle of frequency measure based on double-counter and multi-periods pulse synchronization method, and the designing with microprocessor is offered.
介绍了双计数器多周期同步法频率测量原理，给出了用单片机实现的具体实现方案。
2
For many astronomers, interested in studying specific locations in the sky for extended periods of time, the multi-beam receiver offers no particular advantages.
许多天文学家对长期研究空中的特殊区域都很感兴趣，多波束接收器不提供这方面的特殊便利。
3
The volcanoes in Cenozoic Era of Tengchong have features of large number, wide area, multi types, multiperiods of activities.