Real Cepstrum

Compute real cepstrum of input

• 

Libraries:
DSP System Toolbox / Transforms

Description

The Real Cepstrum block computes the real cepstrum of the input.

Ports

Input

Input — Input

vector | matrix

Specify the input u as a vector or a matrix of size M-by-N. The block treats each column of the input as an independent channel containing M consecutive samples. The block always processes unoriented vector inputs as a single channel, and returns the result as a length-M column vector. The block does not accept complex-valued inputs.

Data Types: single | double

Output

Output — Real cepstrum output

vector | matrix

Real cepstrum output, returned as an M_o-by-N matrix.

When you clear the Inherit FFT length from input port dimensions parameter, M_o is the value you specify in the FFT length parameter. When you select the Inherit FFT length from input port dimensions parameter, M_o = M, where M is the frame size (number of rows) of the input signal.

Each output column contains the length-M_o real cepstrum of the corresponding input column.

The output port rate is the same as the input port rate.

Data Types: single | double

Parameters

Inherit FFT length from input port dimensions — Match the FFT length to the dimensions of the input port

on (default) | off

When you select this check box, the output frame size M_o matches the input frame size M.

FFT length — Compute FFT length

64 (default) | positive integer

The number of frequency points at which to compute the FFT, which is also the output frame size M_o.

Dependency

To enable this parameter, clear the Inherit FFT length from input port dimensions parameter.

Block Characteristics

Data Types	double | single
Direct Feedthrough	no
Multidimensional Signals	no
Variable-Size Signals	no
Zero-Crossing Detection	no

More About

Real Cepstrum

The real cepstrum is the inverse Fourier transform of the real logarithm of the magnitude of the Fourier transform of a sequence.

Here is the equivalent MATLAB^® code for computing the real cepstrum.

y = real(ifft(log(abs(fft(u,Mo)))))

or, more compactly,

y = rceps(u,Mo)

where,

• u –– Input

• y –– Real cepstrum output

• M_o –– Output frame size

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using Simulink® Coder™.

Generated code relies on the memcpy or memset function (string.h) under certain conditions.

Version History

Introduced before R2006a