How to calculate SNR of a signal

Hi Friends,

I'm working on a project where i want to add some white noise to my signal

for testing purpose.

I've designed the noise generator and everything is working fine.

But what are the means through which i can know what exact is the noise
power w.r.t signal that my signal is changing behavioral of signal

on way i thought of is SNR.
But I'm not quit sure how to calculate it practically.


Or to put it in different way is how to calculate Noise Power.


Thanks for your help !


Raj

raj1795 wrote:
> Hi Friends,
>
> I'm working on a project where i want to add some white noise to my
> signal
>
> for testing purpose.
>
> I've designed the noise generator and everything is working fine.
>
> But what are the means through which i can know what exact is the
> noise power w.r.t signal that my signal is changing behavioral of
> signal
>
> on way i thought of is SNR.
> But I'm not quit sure how to calculate it practically.
>
>
> Or to put it in different way is how to calculate Noise Power.
>
>
> Thanks for your help !

Consider some simple relationships:

- The noise power is proportional to the magnitude squared.

- For white noise, it helps to define the spectral density.  Because, after 
all, the power is divided up over frequency.  Thus, we talk about noise 
power in a unit bandwidth.

- Noise adds as the square root of the sum of the squares.

- If you double the bandwidth in which you observe noise (and the noise is 
white so that the spectral density remains constant), then the noise power 
doubles and the noise amplitude increases by sqrt(2).

So, you need to at least define the bandwidth over which the noise resides. 
Then you need to define the bandwidth over which the observation of S+N will 
be done - as it affects the noise level.

fred

On Jan 5, 5:29&#4294967295;pm, "raj1795" <mangesh.j.jad...@emerson.com> wrote:
> Hi Friends,
>
> I'm working on a project where i want to add some white noise to my signal
>
> for testing purpose.
>
> I've designed the noise generator and everything is working fine.
>
> But what are the means through which i can know what exact is the noise
> power w.r.t signal that my signal is changing behavioral of signal
>
> on way i thought of is SNR.
> But I'm not quit sure how to calculate it practically.
>
> Or to put it in different way is how to calculate Noise Power.
>
> Thanks for your help !
>
> Raj

hope this link will help
http://www.dsprelated.com/showarticle/20.php