power spectral density

[manasiri]

power spectral density of square wave

Dear reader

How I can subtract two power spectral density. (noise fft from signal fft).
could the methode help me in noise reduntio?
the frequency band is 30-600 MHz.

thanks.[/code]

How I can separate two signal spectrum from a measured spectrum in spectrum analyzer?
the data of measuered spectrum are available. one signal is a square wave and another is an image signal that added to the square wave (in time domaine).

Like computer graphic card: RGB green signal.

Dear sir i cant use filter because the signal (square) has wide band spectrum.

 

[tiger_shark]

subtract power spectral densities

Hi,

Are you doing this in simulation? is your noise white? Because if your noise is white (like randn function in MATLAB) then you cannot eliminate the noise by subtraction. Subtraction for white noise is like addition and just adds to the power of noise.

Does filtering the out of band noise work for you? Then you can subtract the filtered version of your signal from your original signal and what is left is the noise with almost same level of power in the out-of band and more power (almost double) in the in-band.

Did I understand your question properly?

Regards - TS