# Acoustics Bessel Functions

Tags:
1. Dec 19, 2016

### TekWarfare

1. The problem statement, all variables and given/known data
For the FM modulation, the amplitudes of the side bands can be predicted from

v(t)=ΣAJn(I)sin(ωt)

Where is a sideband frequency and Jn(I) is the Bessel function of the first kind and the nth order evaluated at the modulation index .Given the table of Bessel functions, assuming A=1, and a modulation index of 2, calculate the voltage amplitude in dB for one of the side bands frequencies relative to the amplitude at 500 Hz.

2. Relevant equations
I=frequency deviation/modulator frequency
fc=+/- nfm

3. The attempt at a solution

Reading the table where x=I=2 (modulation index): n=0 gives 0.224 and n=1 gives 0.577 I assume n=1 would correspond to the first pair of sidebands. I don't know what to do beyond this point though.