impulse_rs.1

speech signal process tools

.\" @(#)impulse_rs.1	1.1 (EPI) 12/17/86
.TH IMPULSE_RESP 1\-SPS 12/17/86
.ds ]W "\fI\s+4\ze\h'0.05'e\s-4\v'-0.4m'\fP\(*p\v'0.4m'\ Entropic Processing, Inc.
.SH NAME
.PP
impulse_resp \- Compute unit impulse responses of filters in FILT file.
.SH SYNOPSIS
.PP
.B impulse_resp
.BI \-n " size"
[
.BI \-x " debug_level"
]
[
.BI \-f " range"
]
[
.B \-i
]
[
.B \-s
]
.I input.filt
.I output
.SH DESCRIPTION
.PP
For each record in the specified range in the input FILT file,
.I impulse_resp
reads the filter zfunc (see FILT(5-SPS), SPS(5-SPS)) and computes a
specified number of points of the unit impulse response by using
.IR block_filter (3-SPS)
to filter a sequence consisting of a single 1 followed by zeros.
Normally the result is written as a zfunc with null denominator
in a record in the output, a FILT file.  Tags are copied from input to output.
.PP
Alternatively, output to a sampled-data file may be specified.  In that case,
if there is more than one filter in the input, the output consists of several
sampled-data segments that are simply catenated.  (To recover a particular
segment, it is necessary to use knowledge of the number of points per
segment.)
.PP
If the input or output filename is given as ``\-'', the standard input or
output is used.
.SH SPS PARAMETERS
.PP
The SPS parameter file is not referred to.
.SH SPS HEADERS
The input file is included as the only source file of the output file, and
the reference file of the input file becomes the reference file of the output
file.  The command line is included as a comment in the output file header.
.PP
The generic header item
.I start_rec
in the output header records the number of the starting input record
(counting from 1 for the first in the file).
.PP
The generic header item
.I invert
records the
.I \-i
option (1 if the option was specified, 0 if not).
.PP
When output is to a filter file, the value of
.I hd.filt\->max_num
in the output header is taken from the
.I \-n
input option.  That of
.I hd.filt\->max_den
is zero.  The other items in the filter-file-specific part of the output
header are given null values such as NONE.  The corresponding values from
the input header are available, since the input file is given as the source
of the output file.
.PP
When output is to a sampled-data file, the generic output header item
.I size
records the value specified with the
.I \-n
option, which equals the length of the sampled-data segment written for each
input record.  The sampling frequency
.I hd.sd\->sf
in the output header is arbitrarily set equal to 1.0.
.SH OPTIONS
.PP
The following options are supported.  Values in brackets are defaults.
.TP
.BI \-n " size" "\fR [(no default)]"
This is the number of points of the output impulse response function;
for filter-function output, it equals
.I nsiz
of the output zfunc.  (See SPS(5-SPS).)
.TP
.BI \-x " debug_level" "\fR [0]"
A nonzero value may invoke various debugging messages on the standard error
output.
.TP
.BI \-f " first" : "last" "\fR [(first in file):(last in file)]"
.TP
.BI \-f " first" :+ "incr"
.TP
.BI \-f " first"
In the first form, a pair of unsigned integers specifies the range
of records to be processed.
Either
.I first
or
.I last
may be omitted; then the default value is used.
If
.IR last " = " first " + " incr,
the second form (with the plus sign) specifies the same range as the first.
The third form is equivalent to
.BI \-f " first" : "first;"
it specifies a single record.
If the specified range contains records not in the file,
.I impulse_resp
complains and quits.
.TP
.B \-i
Causes the impulse response of the inverse of each input filter to be
computed, rather than that of the filter itself.
.TP
.B \-s
Specifies output to a sampled-data file rather than to a filter file.
.SH "SEE ALSO"
.PP
block_filter(3-SPS), FILT(5-SPS), SD(5-SPS), SPS(5-SPS)
.SH DIAGNOSTICS
.PP
impulse_resp: unknown option:
.RI \- letter
.br
Usage: impulse_resp \-n size [\-x debug_level][\-f range][\-i][\-s] input.filt output
.br
impulse_resp: output length unspecified or negative
.br
impulse_resp: can't open
.IR filename ": " reason
.br
impulse_resp: 
.I filename
is not an SPS file
.br
impulse_resp: input file
.I filename
is not a filter file.
.br
impulse_resp: bad range:
.I n
records in
.I filename
.br
block_filter: poles[0]=0. Exiting.
.br
impulse_resp: premature EOF encountered.
.SH AUTHOR
.PP
Rodney W. Johnson, Entropic Processing, Inc.