getatal.3

speech signal process tools

.\" Copyright (c) 1987 Entropic Speech, Inc.; All rights reserved
.\ @(#)getatal.3	1.5 07 Nov 1990 ESI
.TH GET_ATAL 3\-ESPSsp 07 Nov 1990
.ds ]W "\fI\s+4\ze\h'0.05'e\s-4\v'-0.4m'\fP\(*p\v'0.4m'\ Entropic Speech, Inc.
.SH NAME
get_atal \- get reflection coefficients from auto-correlations using Levinson.
.SH SYNOPSIS
.ft B
get_atal (r, order, c, rc, pgain)
.br
float    c[], rc[], *pgain;
.br
double  r[];
.br
int     order;
.SH DESCRIPTION
This routine computes the reflection coefficients,
.B
rc[1], ..., rc[order],
and the lpc filter coefficients,
.B
c[1], ..., c[order],
corresponding to the given set of normalized auto-correlation coefficients,
.B
r[1], ..., r[order],
using standard Levinson's algorithm.
If stability problem is encountered in the computation of reflection
coefficient
.B
rc[k],
the reflection coefficients
.B
rc[k]
to
.B
rc[order]
are set to zero and a message is displayed on
.I
stderr.
.SH BUGS
None
.SH COMMENTS
The auto-correlation coefficients needed can be obtained from the data using
.I
get_auto
function.
The maximum value of
.B 
order
allowed is 1000. User should be aware of it.
.SH FUTURE CHANGES
The restriction on
.B
order
will be removed. If instability is noticed during Levinson recursion,
this information should be transmitted back to the calling program
by appropriately changing the parameter
.B
order.
.SH SEE ALSO
get_auto (3-ESPSsp).
.SH REFERENCES
[1] L. R. Rabiner and R. W. Schafer,
.I
Digital Processing of Speech Signals.
Prentice Hall, NJ. 1978.
.SH AUTHOR
Shankar Narayan