FFT for chunk of data from large data

Hello

I have large amount of acceleration data with time

I have sampling rate of 51.2k sample per second. this is for 10 second, total data=512000.

when plotting fft I want to see fft for small periods of data only , say first 1000 periods.

I am able to get fft for whole data (10seconds) but, how to get fft for small perids(1000) and compare it with whole fft?

also, how to increase frequency resolution?

Regards

Vishal

Answer 1

[Sai Sri Pathuri]

I assume you are asking how to get fft of first few samples of the acceleration data. Consider X as your acceleration data. To get fft of first 'n' samples of X, you may use

Y = fft(X(1:n));