快速fourier变换.ppt

文档介绍：Fourier theory made easy (?)
5*sin (24t)
Amplitude = 5
Frequency = 4 Hz
seconds
A sine wave
5*sin(24t)
Amplitude = 5
Frequency = 4 Hz
Sampling rate = 256 samples/second
seconds
Sampling duration =
1 second
A sine wave signal
An undersampled signal
The Nyquist Frequency
The Nyquist frequency is equal to one-half of the sampling frequency.
The Nyquist frequency is the highest frequency that can be measured in a signal.
rier/j2/
Fourier series
Periodic functions and signals may be expanded into a series of sine and cosine functions
The Fourier Transform
A transform takes one function (or signal) and turns it into another function (or signal)
The Fourier Transform
A transform takes one function (or signal) and turns it into another function (or signal)
Continuous Fourier Transform:
close your eyes if you don’t like integrals
The Fourier Transform
A transform takes one function (or signal) and turns it into another function (or signal)
Continuous Fourier Transform:
A transform takes one function (or signal) and turns it into another function (or signal)
The Discrete Fourier Transform:
The Fourier Transform