LPC/RC to Autocorrelation

Convert linear prediction coefficients or reflection coefficients to autocorrelation coefficients

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Libraries:
DSP System Toolbox / Estimation / Linear Prediction

Description

The LPC/RC to Autocorrelation block can convert linear prediction coefficients (LPCs) to autocorrelation coefficients (ACs) or reflection coefficients (RCs) to autocorrelation coefficients (ACs). Set the Type of conversion parameter to LPC to autocorrelation or RC to autocorrelation to select the domain for converting your coefficients.

Ports

Input

A — LPC coefficients

vector | matrix

Specify the LPC coefficients as a vector or a matrix. The block treats each column of the matrix as a separate channel. When you specify an unoriented vector, the block treats the input as one channel.

Dependencies

To enable this port, set Type of conversion to LPC to autocorrelation.

Data Types: single | double

K — RC coefficients

vector | matrix

Specify the RC coefficients as a vector or a matrix. The block treats each column of the matrix as a separate channel. When you specify an unoriented vector, the block treats the input as one channel.

Dependencies

To enable this port, set Type of conversion to RC to autocorrelation.

Data Types: single | double

P — Prediction error power

scalar | vector

Specify the non-unity prediction error power P for each channel as a vector through this port. The length of this vector must equal the number of channels in the input.

Dependencies

To enable this port, set Specify P to Via input port.

Data Types: single | double

Output

AC — Autocorrelation coefficients

vector | matrix

Autocorrelation coefficients, returned as a vector or a matrix.

Data Types: single | double

Parameters

Type of conversion — Type of conversion

LPC to autocorrelation (default) | RC to autocorrelation

Specify the domain for converting the coefficients as one of these:

• LPC to autocorrelation

• RC to autocorrelation

Specify P — Method of specifying prediction error power P

Assume P = 1 (default) | Via input port

Specify the prediction error power P using one of these options:

• Assume P=1 –– Specify the value of P to 1.

• Via input port –– Use the P port to input the value of the actual non-unity prediction error power for each channel. The length of this vector must equal the number of channels in the input.

If first input value is not 1 — Action to take if first input value is not 1

Replace it with 1 (default) | Normalize | Normalize and warn | Error

Specify the action to take if the first coefficient of the LPC coefficient vector is not 1. You can set this parameter to one of these options:

• Replace it with 1 — The block changes the first value of the coefficient vector to 1. The rest of the coefficient values are unchanged.

• Normalize — The block divides the entire vector of coefficients by the first coefficient so that the first coefficient of the LPC coefficient vector is 1.

• Normalize and Warn — The block divides the entire vector of coefficients by the first coefficient so that the first coefficient of the LPC coefficient vector is 1. The block displays a warning message stating that the vector of coefficients has been normalized.

• Error — The block displays an error telling you that the first coefficient of the LPC coefficient vector is not 1.

Dependencies

To enable this parameter, set Type of conversion to LPC to autocorrelation.

Block Characteristics

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

References

[1] Orfanidis, S.J. Optimum Signal Processing. New York, McGraw-Hill, 1988.

[2] Makhoul, J. Linear Prediction: A tutorial review. Proc. IEEE. 63, 63, 56 (1975).

[3] Markel, J.D. and A. H. Gray, Jr., Linear Prediction of Speech. New York, Springer-Verlag, 1976.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced before R2006a