Signal Processing Blockset™

LPC/RC to Autocorrelation - Convert linear prediction coefficients or reflection coefficients to autocorrelation coefficients

Library

Estimation / Linear Prediction

dsplp

Description

The LPC/RC to Autocorrelation block either converts 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 from which you want to convert your coefficients. The A port corresponds to LPC coefficients, and the K port corresponds to the RC coefficients.

The block input must be a sample-based row vector, which is treated as a single channel, or a matrix, which is treated as a single channel per column.

Use the Specify P parameter to set the value of the prediction error power. You can set this parameter to 1 by selecting Assume P=1. When you select Via input port, a P port appears on the block. You can use this 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.

The If first input value is not 1 parameter specifies the behavior of the block when the first coefficient of the LPC coefficient vector is not 1. The following options are available:

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 telling you that your 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.

Dialog Box

Type of conversion: From the list select LPC to autocorrelation or RC to autocorrelation to specify the domain from which you want to convert your coefficients.
Specify P: From the list select Assume P=1 or Via input port to specify the value of prediction error power.
If first input value is not 1: Select what you would like the block to do when the first coefficient of the LPC coefficient vector is not 1. You can choose Replace it with 1, Normalize, Normalize and Warn, and Error.

References

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

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

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

Supported Data Types

Double-precision floating point
Single-precision floating point