Overview

Inverse FFT of real data on fixed point

Discussion

Computes the inverse fast Fourier transform of a complex half spectrum yielding a real-valued result. The blockSize, N, of the real valued output must be a power of 2 in the range [4...1024]. The input pin is complex with a blockSize of N/2+1 complex samples. The input contains the complex transform at samples k=0, 1, ..., N/2. The DC (k=0) and Nyquist (k=N/2) samples always have an imaginary component of 0.

Type Definition

typedef struct _ModuleIfftFract32
{
    ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
    fract32 onebyBlockSize;                       // value of 1/BlockSize in fractional value
} ModuleIfftFract32Class;

Variables

Properties

Name	Type	Usage	isHidden	Default value	Range	Units
onebyBlockSize	fract32	derived	0	0.25	Unrestricted	onebyBlockSize

Pins

Input Pins

Name: in

Description: Complex input

Data type: fract32

Channel range: Unrestricted

Block size range: 3, 5, 9, 17, 33, 65, 129, 257, 513, 1025

Sample rate range: Unrestricted

Complex support: Complex

Output Pins

Name: out

Description: Real input

Data type: fract32

Scratch Pins

Channel count: 1

Block size: 8

Sample rate: 48000

MATLAB Usage

File Name: ifft_fract32_module.m

 M=ifft_fract32_module(NAME)
 Computes the inverse FFT of a real time domain Fractional sequence.  The input
 block is complex valued with a blockSize of N/2+1.  The output is
 real data of length N.  The module supports multichannel signals.
 Arguments:
    NAME - name of the module.