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引言利用贝塞尔函数零值法测量频偏可以获得较高的精度,而且方法简单易行,因此一般用来作为频偏计量标准。但是由于贝塞尔函数的第一个零点值为2.4048(即零阶贝塞尔函数的第一个根值),因此对于测量小调制指数的频偏就有一定的困难,虽然利用定K′_f值法可以用作检定小频偏,但是对于调制指数最大也达不到2.4048的调制器,则直接利用贝塞尔函数零值法就无能为力了。本文在贝塞尔函数零值法的基础上利用倍频法则可以解决小调制指数频偏的测量。
Introduction The use of Bessel zero-value method to measure the frequency offset can obtain high accuracy, and the method is simple and easy, it is generally used as the frequency offset measurement standard. However, since the first zero point value of the Bessel function is 2.4048 (that is, the first root value of the Bessel function of the zeroth order), there is a certain difficulty in measuring the frequency offset of the small modulation index. However, The _f value method can be used as a test for small frequency offsets, but for modulators with a maximum modulation index of less than 2.4048, it is useless to use the Bessel function zero value directly. Based on the zero-value method of Bessel function, this paper can solve the measurement of frequency offset of small modulation index by using frequency multiplication rule.