What purpose is for a sliding FFT on windowing data?

Hi,

I read some codes from some formal demonstration sample project. It is found
 that there are 4 data blocks (one is the present data block). After the 4
 block data windowing, it is sent to an FFT function. The interesting thing
 is that the FFT function is not the same with the windowing block. In fact,
 the FFT is cycled with a fixed data block position (as one data block is 
 getting old in the 4 data blocks). That is, the FFT block begins at 0, 1, 2,
 3 if block 0 is always the latest data block position. I don't know the 
 reason for this arrangement. Can you tell me something about it?

 Thanks, 

On Sun, 12 Apr 2015 16:00:25 -0700 (PDT), fl <rxjwg98@gmail.com>
wrote:

>Hi,
>
>I read some codes from some formal demonstration sample project. It is found
> that there are 4 data blocks (one is the present data block). After the 4
> block data windowing, it is sent to an FFT function. The interesting thing
> is that the FFT function is not the same with the windowing block. In fact,
> the FFT is cycled with a fixed data block position (as one data block is 
> getting old in the 4 data blocks). That is, the FFT block begins at 0, 1, 2,
> 3 if block 0 is always the latest data block position. I don't know the 
> reason for this arrangement. Can you tell me something about it?
>
> Thanks, 

Hello fl,
     It looks like you've received no replies 
to your post.  There are guys here who know something 
about Sliding FFTs.  But I don't think they understand 
the words and phrases you used in your question.
For example, what does "4 block data windowing" and 
"FFT function is not the same with the windowing 
block" mean?

If you can tell us EXACTLY, specifically, what you are 
doing I imagine someone here can provide you with 
a little help.

By the way, the word "window" means different things 
to different people, so when you use the word "window" 
you should carefully describe what that word means to you.

[-Rick-]