xenial (1) signalgen.1.gz

Provided by: siggen_2.3.10-6build1_amd64 bug

NAME

       signalgen - a simple signal generator program

SYNOPSIS

       signalgen [flags] waveform freq
              waveform is sine, cosine, square, triangle, sawtooth, noise

       signalgen [flags] pulse freq [Mark/Space]
              pulse has extra param Mark/Space % - def. is 10 (%)

DESCRIPTION

       signalgen  is  a  simple  signal generator program, that can digitally generate standard waveforms on the
       LINUX /dev/dsp device. 8 or 16 bit samples can be generated, in mono or stereo. In stereo the two signals
       can be in phase or in anti-phase (180 degrees). The frequency is specified as an integer number of Hertz.
       Fractional Hertz frequencies are not supported. Of course, only frequencies less than half the samplerate
       (number of samples/sec) can be generated.

       The waveforms that can be generated are:

       sine   A standard sine wave

       cosine a sine wave with a 90 degree phase shift

       square a standard square wave with a 50% mark space ratio

       sawtooth
              a ramp waveform with 'infinately' fast flyback (:-) An ideal oscilloscope timebase signal.

       triangle
              shaped like equally spaced teeth on a saw (:-)

       noise  This  is  weak.  All  it  consists  of  is one second of pseudo-randomly generated samples, played
              repeatedly. I'd love to do proper white/pink noise, but I don't know enough, and I don't think the
              structure of the program is conducive to accurate noise generation.

       pulse  A square waveform where the mark/space ratio (as a percentage) can be specified. The default value
              is 10% (mark/space ratio of 1:9).

       signalgen creates one second's worth of generated output in a buffer and  plays  the  buffer  repeatedly,
       until it is terminated.

       A  lot  of thought has gone into the algorithms for generating the waveforms.  I believe the sin/cos wave
       to be very pure (modulo your sound card :-), but I don't have access to a THD meter to  measure  it.  For
       best  signal accuracy NEVER use the gain factor option (-A). The generator will then make the wave's peak
       value fit the maximum digital values allowed. Use a mixer program to control the  output  volume,  or  an
       external attenuator.

       The gain factor option can be useful for simulating a signal that has been subject to clipping. Specify a
       gain of > 100%. In fact a trapezoid signal can be made by  generating  a  clipped  triangular  wave.  The
       greater the gain, the closer the signal approaches a square wave (the rise and fall times decrease).

       Defaults
              output to /dev/dsp, 22050 samples/sec, mono, 16 bit samples if possible, else 8 bit.

OPTIONS

       -h     display usage and help info

       -v     be verbose

       -o file
              write digital sample to file ('-' is stdout)

       -w file
              as '-o' but written as a WAVE format file. -a (append) is not valid with this option.

       -f,-a  force overwrite/append of/to file.

       -C file
              use "file" as the local configuration file (see below).

       -s samples
              generate with samplerate of samples/sec

       -8/-16 or -b 8|16
              force 8 bit or 16 bit mode.

       -1,-2,-2a
              mono (def), stereo or stereo in antiphase

       -A n   scale samples by n/100, def. n is 100 (i.e. percentage of full scale output)

       -t N|Nm
              generate output for either N secs or Nm millisecs only.

       -x10 or -x100
              Scale frequencies down by a factor of 10 or 100. This allows fractional Hz values to be generated.
              See EXAMPLES below for its use. It is a Kludge.

EXAMPLES

       signalgen -v sin 440
              generate a sin wave of 440Hz at 22050 samples/sec, 16bit samples on 16 bit card, 8 bit samples  on
              an 8 bit card.

       signalgen -v -s 44100 -w sin444.wav sin 440
              as  above  but  at  a  samplerate  or 44100/sec and save a one second of samples as a WAVE file in
              sin440.wav

       signalgen -v -A 500 saw 1000
              generate a 1000Hz sawtooth wave severely clipped. The waveform will look like a square wave with a
              rise and fall time of one tenth of the wave period. (I think that's what the scribbled calculation
              on the back of this envelope gives :-)

       signalgen -v -2a sin 1000
              generate 2 1000Hz sine waves out of phase by 180 degrees, one on each stereo channel.

       signalgen -v pulse 1000 95
              generate a 1000Hz pulse wave with the 'on' period  being  95%  of  the  waveform  period,  i.e.  a
              mark/space ratio of 19:1.

       signalgen -v -x10 sin 2616
              generate  middle  C  261.6Hz  (2616/10)  from  the  equally  tempered scale. Yes it's a royal pain
              remembering to scale all freqs. by a factor of 10, but I needed it in a hurry and didn't have time
              to do it better.

CONFIGURATION FILES

       Three  possible  configuration  files  can be used: a LOCAL config file (usually in current directory), a
       HOME config file in user's $HOME directory and a GLOBAL config file.

       All the siggen suite of programs are compiled with the names of the config files built in. By default the
       configuration files are:

       ./.siggen.conf
              is the LOCAL config file.

       $HOME/.siggen.conf
              is the HOME config file.

       /etc/siggen.conf
              is the GLOBAL config file.

       signalgen -h
              will indicate which config files will be searched for.

       The  config  files  do  not  have  to exist. If they exist and are readable by the program they are used,
       otherwise they are simply ignored.

       The config files are always searched for configuration values in the  order  LOCAL,  HOME,  GLOBAL.  This
       allows  a scheme where the sysadmin sets up default config values in the GLOBAL config file, but allows a
       user to set some or all different values in their own HOME config file, and  to  set  yet  more  specific
       values when run from a particular directory.

       If  no  configuration  files exist, the program provides builtin default values, and most of these values
       can be set by appropriate command line switches and flags.

       See siggen.conf(5) for details of the configuration files.

       signalgen looks for configuration values CHANNELS, DACFILE, SAMPLERATE, SAMPLESIZE, VERBOSE.

       CHANNELS
              sets either mono or stereo mode like the '-1|-2' options.

       DACFILE
              allows the name of the DAC/DSP/PCM device to be changed from /dev/dsp

       SAMPLERATE
              sets the number of samples/sec for the DAC device

       SAMPLESIZE
              sets whether 8 or 16 bit samples to be generated

       VERBOSE
              sets whether or not to run in verbose mode.

SEE ALSO

       siggen.conf(5)

BUGS

COPYING

       Copyright 1995-2008 Jim Jackson

       The software described by this manual is covered by the GNU General Public License, Version 2, June 1991,
       issued by :

              Free Software Foundation, Inc.,
              675 Mass Ave,
              Cambridge, MA 02139, USA

       Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice
       and this permission notice are preserved on all copies.

       Permission is granted to copy and distribute modified versions of this manual under  the  conditions  for
       verbatim  copying,  provided  that  the entire resulting derived work is distributed under the terms of a
       permission notice identical to this one.

       Permission is granted to copy and distribute translations of this manual into another language, under the
       above conditions for modified versions, except that this permission notice may be included in translation
       instead of in the original English.

AUTHOR

       Jim Jackson

       Email: jj@franjam.org.uk