comparison man/man1/fft.1 @ 0:5242703e91d3 tip

Initial checkin for AIM92 aimR8.2 (last updated May 1997).

+.TH FFT 1 "15 September 1993"
+
+.SH NAME
+fft \- Fast Fourier transform of contiguous frames.
+
+
+.SH SYNTAX 
+fft  [arguments]  [file]
+
+
+.SH DESCRIPTION
+Several forms of fft processing are provided, according to the "spectrum"
+option. Unless verbose output is requested, all input and output is in
+binary shorts.
+
+Each input frame is padded with zeroes to the next power of 2 larger than
+the input framewidth.
+If necessary, extra padding can be enforced using the (silent) padding option
+to add extra zeroes, padding to a larger power of 2.
+The amount of extra padding is "exponential", expanding the basic size to:
+
+      ( framewidth + padding ) * 2**n
+
+where the padding option is n.
+
+(n=0 by default, so that no extra padding is added. When n=1 then padding is
+added to double the size, and when n=2 the size is quadrupled, etc.).
+The input and output frame sizes in sample points may be printed using the
+"size" option.
+
+
+.SH OPTIONS
+
+The spectrum option selects a form of processing from the list:
+
+1. magnitude: magnitude spectrum
+
+2. log: log10 of magnitude spectrum
+
+3. phase: phase spectrum.
+
+4. complex: full complex spectrum, in <real,imag> pairs.
+
+5. inverse: inverse fft, reading framewidth numbers which are interpreted as
+<real,imag> pairs, (ie framewidth/2 complex numbers),
+and outputs the inverse transform scaled by 1/framewidth.
+
+6. verbose: prints the spectrum in ASCII on the stdout.
+
+.SH EXAMPLES
+.nf
+1. To print the input and output frame sizes in sample points,  
+   eg for a subsequent plotting program, use the size option:
+
+fft ... size=on
+
+
+2. An fft of a waveform sampled at 10kHz, computed within a 
+   frame of 12.8ms, plotting the 2nd frame in a sequence of 
+   frames with half-frame overlap.
+
+fft samp=10kHz width=12.8ms frstep=6.4ms frame=2 file | x11plot
+
+
+3. An animated plot of successive fft spectra of a waveform 
+   sampled at 10kHz, each computed within a frame of 12.8ms, 
+   and shifted by 2 sample points.
+
+fft samp=10kHz width=12.8ms frstep=2p file | x11play -n64
+
+
+4. Using the complex output from fft, and inverse transform 
+   without windowing to recover original input.
+
+fft samp=10kHz frame=2 spec=complex window=off file > foo
+fft samp=10kHz frame=1 spec=inverse window=off foo | x11plot
+
+.fi
+
+.SH COPYRIGHT
+.LP
+Copyright (c) Applied Psychology Unit, Medical Research Council, 1995
+.LP
+Permission to use, copy, modify, and distribute this software without fee 
+is hereby granted for research purposes, provided that this copyright 
+notice appears in all copies and in all supporting documentation, and that 
+the software is not redistributed for any fee (except for a nominal 
+shipping charge). Anyone wanting to incorporate all or part of this 
+software in a commercial product must obtain a license from the Medical 
+Research Council.
+.LP
+The MRC makes no representations about the suitability of this 
+software for any purpose.  It is provided "as is" without express or 
+implied warranty.
+.LP
+THE MRC DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING 
+ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL 
+THE A.P.U. BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES 
+OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, 
+WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, 
+ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS 
+SOFTWARE.
+