User`s guide

FFT
5-180
convolve signals by taking the FFT of time domain data, multiplying
frequency-domain data, and inputting the product to an IFFT block.
The following model shows the implementation of the Overlap-Save FFT Filter
block. The implementation uses the FFT block in conjunction with an IFFT
block, so the FFT block is set to output in bit-reversed order, and the IFFT
block is set to accept inputs in bit-reversed order. Note that the
bitrevorder
function is used to reorder a vector processed with the FFT outputs.
Click here in the MATLAB Help browser to open the demo model.
Alternatively, type the following command in MATLAB.
olapfilt % Open the following demo model
To see the implementation of the Overlap-Save FFT Filter block, right-click on
the Overlap-Save FFT Filter block, and select
Look under mask. Look under
the mask of the Overlap-Add FFT Filter block as well, which also uses an FFT
block that outputs in bit-reversed order.
Implementation of the Overlap-Save FFT Filter Block
FFT block set to output
in bit-reversed order.
IFFT block set to accept
inputs in bit-reversed
order
bitrevorder function used to
comply with ordering of FFT output