refcof.1

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.TP
.BI \-c " conv_test\fR[1e-5]\fP"
Specifies, for the STRCOV method only (not including STRCOV1), 
a convergence test value.  The lower the value, the smaller the 
change required on each iteration before the estimator terminates, 
and the more iterations that normally will result.  
.TP
.BI \-i " max_iter\fR[20]\fP"
Specifies, for the STRCOV method only (not including STRCOV1), the 
maximum number of iterations that the estimator will run through 
before terminating.  A warning will indicate if the estimator
terminates because max_iter has been exceeded. 
.TP
.BI \-o " order\fR[15]\fP"
Specifies the order (number of reflection coefficients), and
overrides the value that may be in the parameter file.  The default
applies only if there is no value in the parameter file.  
.TP
.BI \-s " sinc_n"
For the AUTOC, STRCOV, and STRCOV1 methods, the autocorrelation 
the autocorrelation function is multiplied by the function
.I sin (x / sinc_n) 
before computing the reflection coefficients.  In the frequency
domain this has the effect of convolving the spectrum with a boxcar
function of width
.I "f / sinc_n,"
where
.I f
is the sampling frequency.  The value of
.I sinc_n
is recorded in a generic header item.
.TP
.B \-d
Specifies that the dc component of each frame is removed before 
the analysis is performed.  DC revmoval takes place before windowing.
.TP
.B \-Z
If the last frame normally would overrun the stated range,
\fIrefcof\fP reads past the range to fill up the last frame; if the 
the last would go past the file end, the frame is filled with zoes. 
Use of \fB-Z\fP, inhibits this behavior by processing one less frame.
The result is that the end of the last frame falls short of the stated
range.  A common use of \fB-Z\fP is to avoid getting unwanted zeros
in training sequences.  
.TP
.B \-z
Specifies that /fIrefcof/fP operate silently, without issuing various 
warnings. 
.TP
.BI \-x " debug_level" "\fR [0]"
A positive value specifies
that debugging output be printed on the standard error output.
Larger values result in more output.
The default is 0, for no output.
.br
.SH ESPS PARAMETERS
.PP
The parameter file is not required to be present, as there are 
default parameter values that apply.  If the parameter file 
does exist, the following parameters are read:
.TP
.I "start - integer"
.IP
The first point in the input sampled data file that is processed.  A
value of 1 denotes the first sample in the file.  This is only read
if the \fB\-p\fP option is not used.  If it is not in the parameter
(or Common) file, the default value of 1 is used.  
.TP
.I "nan - integer"
.IP
The total number of data points to process.  If 
.I nan
is 0, the whole file is processed.  
.I Nan
is read only if the \fB\-p\fP option is not used.  (See the 
discussion under \fB\-l\fP).
.TP
.I "frame_len - integer"
.IP
The number of points in each frame.  This parameter is not read if the
.B \-l
option is specified.  A value of 0 indicates that a single frame of length
.I nan
is processed; this is also the default value in case
.I frame_len
is specified neither with the
.B \-l
option nor in the parameter file.
.TP
.I "step \- integer"
Initial points of consecutive frames differ by this number of samples.
This parameter is not read if the
.B \-S
option is specified.
If the option is omitted and no value is found in the parameter file,
a default equal to
.I frame_len
is used (resulting in exactly abutted frames).
.TP
.I "window_type \- string"
The data window to apply to the data.
This parameter is not read if the command-line option
.B \-w
is specified.
If the option is omitted and if no value is found in the parameter file,
the default used is "RECT", for a rectangular window with amplitude one.
Other acceptable values include
"HAMMING", for Hamming, and "TRIANG", for triangular;
see the window(3-ESPSsp) manual page for the complete list.
.TP
.I "order - integer"
.IP
The number of reflection coefficients computed for each frame of input data.
If no value is given in the file, a default value of 15 is used.  This value 
is not read if the command line option \fB\-o\fP is used.  
.TP
.I "method - string"
.IP
The spectrum analysis method to use.  The available methods are
autocorrelation ("auto"), covariance ("covar"), Burg ("burg"),
modified Burg ("mburg"), fast modified Burg method ("fburg"),
stuctured covariance ("strcov" and "strcov1"), and vector Burg
("vburg", a fast approximation to structured covariance.  If no value
is given in the file, the autocorrelation method is used by default.
The \fImethod\fP is not read from the parameter file if the command
line option \fB\-m\fP is used.
.TP
.I "preemphasis - float"
.IP
The preemphasis factor to be applied to input signal.
.TP
.I "strcov_test - float"
.IP
If STRCOV is used, this is the convergence test value (the lower 
the value, the smaller the change per iteration before termination).  
This is not read if \fB-c\fP is used. 
.TP
.I "strcov_maxiter - int"
.IP
If STRCOV is used, this is the maximum number of iterations allowed
before the estimator terminates.  This is not read if \fB-i\fP is
used.
.PP
The values of parameters obtained from the parameter file are printed
if the environment variable ESPS_VERBOSE is 3 or greater.  The default
value is 3.
.SH ESPS COMMON
.PP
ESPS Common is read provided that Common processing is enabled and 
that the 
.I filename
entry in Common matches 
.I file.sd,
in which case parameters present in Common override values from
the parameter file, which in turn may be overriden by command
line options (see the discussion in ESPS PARAMETERS and under
each option).
Common is not read if 
.I file.sd
is standard input.  
If 
.I file.rc
is not standard output and 
.I file.sd
is not standard input, the Common parameters 
\fIfilename\fP (= file.sd), \fIprog\fP (= refcof), 
.I start,
and
.I nan
are written to ESPS Common.
.PP
ESPS Common processing may be disabled by setting the environment
variable USE_ESPS_COMMON to "off".  The default ESPS Common file 
is .espscom in the user's home directory.  This may be overidden by
setting the environment variable ESPSCOM to the desired path.  User
feedback of Common processing is determined by the environment
variable ESPS_VERBOSE, with 0 causing no feedback and increasing
levels causing increasingly detailed feedback.  If ESPS_VERBOSE is not
defined, a default value of 3 is assumed.
.SH ESPS HEADER
A new file header is created for the FEA_ANA file.  The sampled data header
from the input header is added as a source in the output file header, and
the command line is added as a comment.  The input file \fIfile.sd\fP is
set as the reference header for tags.
.PP
The program writes the usual values into the common part of the
output header.  
.I Refcof
writes the following values into the specified generic header items
in the output FEA_ANA file:
.nf
.sp
\fIorder_vcd\fP = 0
\fIorder_unvcd\fP = order
\fImaxpulses\fP = 1
\fImaxraw\fP = 1
\fImaxlpc\fP = 1
\fIspec_rep\fP = RC
\fIstart\fP = start
\fInan\fP = nan;
\fIfrmlen\fP = frame_len;
\fIsrc_sf\fP = sample frequency of file.sd
.fi
.PP
In addition, the following generic header items are created
and filled with values used by \fIrefcof\fP: \fImethod, window_type, 
DC_removed, step.  \fPAll of these are CODED types, except for \fIstep\fP, 
which is LONG.  If a non-zero preemphasis factor is used, then
the header item \fIpreemphasis\fR of FLOAT type is also written.
.PP
The generic header item \fIstart_time\fP (type DOUBLE) is written in
the output file.  The value written is computed by taking the
\fIstart_time\fP value from the header of the input file (or zero, if
such a header item doesn't exist) and adding to it the offset time
(from the beginning of the input file) of the first point processed
plus one half of \fIframe_len\fP (thus, \fIstart_time\fP is middle of
the first frame, which is appropriate since the output data represent
the entire frame; without this adjustment for \fIframe_len\fP,
\fIwaves\fP+ displays would not line up properly.  
.PP
The generic header item \fIrecord_freq\fP (type DOUBLE) is written in
the output file.  The value is the number of output records per second
of input data.
.SH  SEE ALSO
.PP
\fIget_resid\fP (1\-\s-1ESPS\s+1), \fImask\fP (1\-\s-1ESPS\s+1),
\fIget_f0\fP (1\-\s-1ESPS\s+1), 
.br
\fIps_ana\fP (1\-\s-1ESPS\s+1),
\fItranspec\fP (1\-\s-1ESPS\s+1), \fIspectrans\fP (1\-\s-1ESPS\s+1),
.br
\fIme_spec\fP (1\-\s-1ESPS\s+1), \fIplotspec\fP (1\-\s-1ESPS\s+1),
\fIexprompt\fP (1\-\s-1ESPS\s+1), 
.br
\fIexpromptrun\fP (1\-\s-1ESPS\s+1),
\fIfft\fP (1\-\s-1ESPS\s+1), \fIcompute_rc\fP (3\-\s-1ESPS\s+1),
.br
FEA_ANA (5\-\s-1ESPS\s+1), FEA (5\-\s-1ESPS\s+1), FEA_SD
(5\-\s-1ESPS\s+1)
.sp
.SH BUGS
.PP
None known. The program will not compute reflection coefficients of complex
signals; if presented with complex input data, it will warn and exit.
.SH FUTURE CHANGES
.PP
None contemplated.
.SH REFERENCES
.PP
.TP
[1] 
L. R. Rabiner and R. W. Schafer, 
\fIDigital Processing of Speech Signals\fP,
Prentice Hall, NJ. 1978.
.TP
[2]
J.P.Burg, D.G.Luenberger, D.L.Wenger, "Estimation of Structured
Covariance Matrices" \fIProceedings of the IEEE\fP, Vol. 70, No. 9
September 1982
.TP
[3]
Shankar Narayan and J.P. Burg, "Spectral Estimation of Quasi-Periodic
Data", \fIProceedings ICASSP 87\fP, pp. 944-947.  
.sp
.SH  AUTHOR
.PP
Original program by Brian Sublett. 
.PP
Modified extensively by John Shore.