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通过对频率源稳定度的时域测量进行极低频谱分析是一种有效方法。哈德玛方差的传递函数由于具有选频特性,因而可用来进行频率源相对频率噪声谱S_y(f)分析。本文从最佳“频窗”传递函数出发,利用沃尔什函数的性质,获得了频率短期稳定度的新表征——沃尔什正弦方差。它能够充分发挥微型计算机优良的数值计算和系统控制功能,灵活、方便地获得频率源短期稳定度的各种表征,特别在测试S_y(f)时,基本克服了哈德玛方差传递函数的谐波及其旁瓣所带来的误差,并可通过数据复用大大缩短测试时间。文中给出了沃尔什正弦方差与阿仑方差及哈德玛方差的关系,指出它在获取频率短期稳定度方面具有内在含义。
Very low frequency spectrum analysis by time-domain measurements of frequency source stability is an effective method. The Hadamard variance transfer function can be used to analyze the relative frequency noise spectrum S_y (f) of the frequency source because of its frequency selectivity. In this paper, starting from the best “window” transfer function and using the properties of the Walsh function, a new characterization of the short-term stability of the frequency-Walsh sine variance is obtained. It can give full play to microcomputer numerical and system control functions, flexible and easy to obtain a variety of short-term stability of the source of the characterization, especially in the test S_y (f), basically overcome the Harmonic variance transfer function harmonic Its side lobe brought about by the error, and can greatly reduce the test time multiplexing of data. The paper gives the relationship between the Walsh sine variance and the Allan variance and the Hadamard variance, and points out that it has intrinsic meaning in obtaining short-term frequency stability.