【摘要】 介绍了数字卫星电视传输系统结构及其抖动特性的建模,提出了一种刻画系统抖动特性模型的精确模拟方法,给出了利用直接数字频率合成器(DDS)AD9952的设计方案。设计研制了抖动模拟器,可以分别对系统抖动特性和卫星多普勒频偏进行模拟,并给出了模拟器模拟性能的理论计算。研究结果表明,设计方案切实可行,已被用于数字电视传输网络测试中,运行效果良好,具有较高的实用价值。更多还原

【Abstract】 Firstly,the structure of the digital satellite TV transmission system is briefly introduced and the total jitter of the system is characterized in this paper.Then a precise method of jitter simulation by characterizing the distribution of the total jitter is proposed.A simulator which is based on a direct digital frequency synthesizer(DDS),AD 9952,is designed to simulate the jitter characterization and the simulator could also model the Doppler frequency shift when using a nongeostationary satellite.The bounds of the simulation performance of the simulator are also calculated.Results show that the simulator could feasibly emulate the total jitter and the Doppler shift of the system,and meet the practical interests.The simulator has been applied in the digital satellite TV system for measurements and obtained satisfactory results.更多还原