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Measurements >> Phase Noise and Jitter Measurements >> How to calculate phase noise of a frequency modulate signal
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Message started by icemc2008 on Apr 18^th, 2011, 1:09am

Title: How to calculate phase noise of a frequency modulate signal
Post by icemc2008 on Apr 18^th, 2011, 1:09am

Hello everyone,

I am a newbie in phase noise and jitter. I want to ask how to calculate the phase noise of a frequency modulate signal.

Ex: I have a sine wave of 10MHz and 0.5V - > - 0.5V amplitude. a modulation signal: a sine wave with 10kHz frequence and 1MHz amplitude(deviation).

I want to calculate the phase noise of this modulated signal. please give me a expression and example to calculate it with the data above.

please help me, thanks a lot for your kind and patience!!!

Title: Re: How to calculate phase noise of a frequency modulate signal
Post by raja.cedt on Apr 18^th, 2011, 11:11am

hi,
most of the noise in oscillators coming from phase so forget about amplitude noise. Coming to the phase noise, it is the single side band noise to carrier power ratio. But for the present scenario you have given its mainly spur level rather than calling as phase noise, because there only one noise component @ 10k so it reflects as noise spur at your oscillator o/p. spur level is 20log(beta), where beta=frequency deviation/center frequency. Just read FM basics.

get back to m if you have any questions..
Thanks.
Raj.