sum of signal noise ratio?

[hh]

If you have two system, one SN is a, another is b. If they are summed, what is SN?
Assuming they can be summed for same properties.


Hui

 

[Joe McElvenney]

Hi,

If you have two system, one SN is a, another is b. If they are summed, what is SN?
Assuming they can be summed for same properties.

In the case of two uncorrelated noise sources mixed with
identical signals of the same amplitude, I think there should be
a 3dB improvement in S/N ratio. The voltage resulting from two
such noise signals would be equal to the square-root of their
sum but the signals alone would add normally.

That is, uncorrelated noise powers add normally but the sum of
their voltages do not.


Cheers - Joe

 

[Joe McElvenney]

Hi,

Oops! the last sentence should read -

That is, uncorrelated noise powers add normally but
their voltages do not.


Cheers - Joe