# Autocorrelation

Started by November 17, 2008
```Hi,
I am trying to understand the autocorrelation function for better timing
resolution. I am bit confused how to find out the auto correlation PEAK
from the output of M-Sequence? and What is the impact of distance between
the two peaks? In other words, the impact of the length of the M-Sequence?

Thanks,

```
```For M-sequences the autocorrelation should have a peak after every
2^M-1 symbols.
"How to find auto-correlation"?? I don't get the question.
Autocorrelation is always defined as..
r(tau) = Sum_t { x(t) x(t+tau)}.
The impact of distance between two peaks is the ambiguity resolution.
We know the exact timing of the signal excepting the ambiguity of
2^M-1. In practical systems we make M big enough that we don't see the
other peak.

Regards
Piyush

On Nov 17, 9:01&#2013266080;pm, "angelredrose" <el...@leeds.ac.uk> wrote:
> Hi,
> I am trying to understand the autocorrelation function for better timing
> resolution. I am bit confused how to find out the auto correlation PEAK
> from the output of M-Sequence? and What is the impact of distance between
> the two peaks? In other words, the impact of the length of the M-Sequence?
>
> Thanks,

```