Hi,

I'm a mechanical engineer, and just enroll in digital signal processing this year. I was never into signal stuff before.

I was trying to figure out the highlights on my attachment. After looking for them on Google, I was more confusing. Could you give me
a guideline or the quickest way or how to start learning these?

 

The purpose of an auto-correlation function is to identify the level of correlation between one part of a signal and another part. As you can imagine it is very good at identifying signals with repetitious patterns in them.

https://en.wikipedia.org/wiki/Autocorrelation

They can be computed as either a continuous function or a discrete function, depending on the input data, if the functions are square integrable or square summable.