An Algorithm for Measuring FM Signal Frequency Modulation Index by Bessel Function Ratio Method

In this paper, by combining the first kind of Bessel function with the principle and characteristics of FM signal, the spectral image characteristics of FM signal can be observed, the mathematical relationship between carrier frequency components and different side frequency components and the first kind of Bessel function is obtained, and the ratio method of Bessel function is improved. In order to verify the accuracy and measurement accuracy of the method, The simulation experiment is carried out based on MATLAB simulation software and the test is carried out by STM32H750 series single chip microcomputer. Bessel function ratio method is simple and clear, the measurement error of FM index is less than 0.1, the precision is high, the running speed is fast, and the hardware limitation is reduced.