FM and phase/frequency deviation

I have a small understanding issue here, so I would be very glad if someone could help me a bit!

We are given this FM modulated signal to volts;

Xfm (t) = cos[2*pi*(10^8)*t + 5*sin(pi*t(10^4)) + 3*sin(2*pi*t(10^4)) ] , on a R=50 Ohm.


Find phase and frequency deviation.

I have solved similar exercises, bet there was only one sin(...).

We know that Ufm(t) = Acos(ωt + βsinωt).

Which one here is the β? is it the max value?

For frequency deviation, I know that I have to take the derivative of phase in regard to time. But here is looks like there are two phases on the signal? Do I have to get the one with higher coefficient?

• I'm not a radio guy, but is that even an FM signal? Shouldn't it be a central carrier 100MHz and sidebands. (FM sidebands are cool.. the modulation index contains Bessel functions.) to the OP, I'm sorry I don't know the definition of the frequency or phase deviation. The bandwidth of a real FM signal depends on the modulation index. Sep 15, 2014 at 22:45