Abstract—FM/PM signal is widely used in communications, so the detection of FM/PM signal is very important. Modulation index estimation is of great significance for identification and demodulation of FM/PM signal. Based on the analysis of existing algorithms, this paper proposes an improved algorithm by introducing wavelet transform into FM/PM modulation index estimation. The existing modulation index estimation algorithms can be easily affected by noise and the estimation accuracy is too poor to meet the actual demand. The improved algorithm using wavelet transform to reconstruct signal can effectively suppress noise and improve the accuracy of modulation index estimation. Simulation shows that using the proposed algorithm, the estimation accuracy for modulation index is greatly improved with RMSE (the root-mean-square error) of the modulation index estimation being less than 0.05 when SNR≥15dB (the signal-to-noise ratio). 

Index Terms—information processing technology, modulation index estimation, wavelet transform, FM/PM signal

Cite: Zengmao Chen and Shijian Wang, "An Improved Algorithm of Modulation Index Estimation for FM/PM Signal," International Journal of Signal Processing Systems, Vol. 7, No. 2, pp. 49-53, June 2019. doi: 10.18178/ijsps.7.2.49-53