# oversampling

Started by May 22, 2009
```Assume i receive a signal and perform direct conversion from passband
to baseband with a front end analog filter with bandwidth +/- B for my
signal.  In my ADC I sample at 2B and have a signal plus noise limited
to the band +/-B with each noise sample assumed to be uncorrelated.
If i instead decide to sample the signal at the output of the analog
filter at 10B i will have correlated noise on the samples.

Does this mean that if i have a simulation with oversampling greater
than 2B, i have to add non-white noise prior to performing any signal
processing on the samples?

CW
```
```On Fri, 22 May 2009 07:03:53 -0700, CW wrote:

> Assume i receive a signal and perform direct conversion from passband to
> baseband with a front end analog filter with bandwidth +/- B for my
> signal.

This must be homework, because only in a homework problem or a classroom
do you encounter a perfectly bandlimited signal.  They simply don't occur
in nature (feel free to explain why).

> In my ADC I sample at 2B and have a signal plus noise limited
> to the band +/-B with each noise sample assumed to be uncorrelated. If i
> instead decide to sample the signal at the output of the analog filter
> at 10B i will have correlated noise on the samples.

Will you?  Where is the noise coming from?  Will _all_ the noise in a
_real_ system come from _just_ the sources that are spelled out in a
homework assignment?

> Does this mean that if i have a simulation with oversampling greater
> than 2B, i have to add non-white noise prior to performing any signal
> processing on the samples?

Maybe.  What are you simulating?

--
www.wescottdesign.com
```