How to measure the deviation frequency of a Fm-PLL wave?

[rellutzu]

devation frequency

Can anyone indicate me how to measure the deviation freq of a Fm-PLL wave?
I mean I have the unmodulated wave, the modulated one and i must measure this deviation.
I tried on a LeCroy oscillopcope and I obtained the sigma parameter, which is the standard deviation.
From now on, I need a math formula (FFT or something) to calculate the deviation!

Anyone?

THX!

 

[flatulent]

Re: Deviation Frequency

There are certain combinations of modulating frequency and deviation that make the carrier amplitude go to zero. You will have to look this up somewhere to find the argument of the Jo Bessel function. My rusty memory says the argument is the ratio of deviation and modulating frequency and Jo goes to zero around two.

Use a spectrum ananlyzer or a FFT function on your scope to measure the carrier amplitude.