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Filter input signal in the frequency domain

**Library:**DSP System Toolbox / Filtering / Filter Implementations

The Frequency-Domain FIR Filter block implements frequency-domain, fast
Fourier transform (FFT)-based filtering to filter a streaming input signal. In the time
domain, the filtering operation involves a convolution between the input and the impulse
response of the finite impulse response (FIR) filter. In the frequency domain, the
filtering operation involves the multiplication of the Fourier transform of the input
and the Fourier transform of the impulse response. The frequency-domain filtering
becomes more efficient than time-domain filtering as the impulse response grows longer.
This block uses the overlap-save and overlap-add methods to perform the frequency-domain
filtering. For filters with a long impulse response length, the latency inherent to
these two methods can be significant. To mitigate this latency, the
Frequency-Domain FIR Filter block partitions the impulse response
into shorter blocks and implements the overlap-save and overlap-add methods on these
shorter blocks. To partition the impulse response, select the **Partition
numerator to reduce latency** check box. For more details on these two
methods and on reducing latency through impulse response partitioning, see Algorithms.

[1] Stockham, T. G., Jr. "High Speed Convolution and Correlation."
*Proceedings of the 1966 Spring Joint Computer Conference,
AFIPS,* Vol 28, 1966, pp. 229–233.

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