<FONT face=Verdana>Modulation index estimation has important significance in demodulation

FM/PM classification of angle modulation signals

etc. First

angle modulation signals using monotone

PSK

FSK and so on as message signals

are analyzed in time and frequency domain. Then

uniform mathematical representation is constructed for angle modulation signals. Finally

a blind estimation algorithm for modulation index without any prior knowledge is deduced. Simulation results indicate that the algorithm is effective for modulation index estimation with above message signals.