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       glfer - spectrogram display and QRSS keyer


       glfer [OPTIONS] ...


       glfer  is  a  program that displays the power spectrum of a signal as a
       function of time in a format known as a waterfall display; this is also
       called  a  spectrogram.   The horizontal axis represents time. The time
       scale depends on the sample rate and the number of points per FFT.  The
       vertical  axis  represents  frequency, from DC to the Nyquist frequency
       (half the sample rate).  The estimated power of  the  input  signal  is
       indicated  by  the  color; the spectrogram window has an automatic gain
       control (AGC) that ensures  always  the  maximum  visual  contrast  and
       which, in the current version, cannot be disabled.

       Resizing  the  main window in the horizontal direction just changes the
       length of the  time  scale;  resizing  it  in  the  vertical  direction
       enlarges  the  portion  of  spectrum  shown  in  the window. The entire
       spectrum can be seen by scrolling  the  spectrogram  window  using  the
       scrollbar  on  the  right.  Moving the mouse pointer on the spectrogram
       window shows the frequency corresponding to the  pointer  position  and
       the signal power at that frequency on the status line at the bottom.

       The  first  time  glfer  is  run  it  will ask to select a control port
       (serial or parallel) for the TX  keying  functions;  if  the  mouse  is
       connected  to the serial port be sure NOT to select its serial port for
       controlling the TX otherwise the system may hang.  All the settings can
       be   saved  to  a  configuration  file;  in  this  case  they  will  be
       automatically loaded when glfer is launched.

       Please note that the program must be run as root (or suid root) to gain
       access to the transmitter control (parallel or serial) port.

       You may have to use a separate mixer program to adjust the input volume
       and to enable the desired input.


       glfer can use several different  spectral  estimators  to  compute  the
       input signal power spectrum:

       the "classical" periodogram, which is obtained as the squared amplitude
       of the discrete Fourier transform,  after  tapering  the  data  with  a
       "window  function"  selectable  among  the Hanning, Blackman, Gaussian,
       Welch, Bartlett, Rectangular, Hamming and Kaiser types. As  usual,  the
       FFT  number of points and the overlap between data blocks can be freely

   Multitaper method
       The  multitaper  method  is  a  weighted  combination  of  periodograms
       computed  with  different windows, all belonging to the same family and
       having certain peculiar properties.

       This method was described by David J. Thomson in  "Spectrum  Estimation
       and Harmonic Analysis", Proc. IEEE, vol.70, Sep. 1982.  Besides the FFT
       size and overlap, it is possible to change also  a  relative  bandwidth
       parameter and the number of windows to use for the analysis.

       This method requires more CPU power than the first one, due to the fact
       that several FFTs are performed  on  the  same  block  of  data,  using
       different  windows.  The  resulting  spectrum is similar to a classical
       periodogram, but with much less variance (i.e. less  variation  in  the
       background  noise  [speckle]).  Performances  are  also  similar to the
       periodogram, maybe it makes detection of QRSS signals a little  easier,
       but this doesn’t means they are always more readable.

   High performance ARMA
       The  (so  called)  "high performance" ARMA model assumes that the input
       signal is composed only  of  white  noise  plus  a  certain  number  of
       sinusoids  and  tries  to  extract  the  relevant parameters (sinusoids
       frequency and strenght) from the data.

       Reference   article   for   this   implementation   is   "Spectral   An
       Overdetermined  Rational  Model Equation Approach", by James A. Cadzow,
       Proc. IEEE, vol.70, Sep. 1982.

       At present this method is still experimental. There are two  parameters
       that  can  be varied: t is the number of samples used for computing the
       samples autocorrelation and p_e is the order  of  the  AR  model.  This
       latter  must  be less than t, and both number should be fairly small in
       order not to overload the CPU. The number  of  sinusoids  is  estimated
       autimatically  from  the  samples  autocorrelation.   Use  the  default
       numbers  as  a  starting  point  and  experiment!   Unfortunately  this
       spectral  estimator  performs  poorly  with non-white noise (as we have
       usually in the RX audio, due to the IF filters) and high noise  levels.
       On  the  other hand it provides a very good visual SNR with signals not
       buried in the noise

       This method is experimental


       -d, --device FILE
              use FILE as audio device (default: /dev/dsp)

       -f, --file FILENAME
              take audio input from FILENAME (WAV format)

       -s, --sample_rate RATE
              set audio sample rate to RATE Hertz (default: 8000)

       -n N   number of points per FFT to N (preferably a power of 2, default:

       -h, --help
              print the help

       -v, --version
              display the version of glfer and exit


              User startup file.


       There  was some report of problems in the audio acquisition routine, it
       seems that some audio card/driver don’t work  well  with  select;  this
       needs further investigation


       Maybe  the  Spectrogram  should  scroll  as  in other programs, all the
       picture moving right to left

       Jason decoder (in progress)

       Spectrogram speed independent of FFT size


       This man page documents glfer, version 0.4.2


       glfer was written by Claudio Girardi <>


       You  are   welcome   to   send   bug   reports   to   Claudio   Girardi
       <>.   It  would  be  helpful  to  include  with  the  bug
       description also the output of the configure script.


       Copyright © 2010 Claudio Girardi <>

       This program is free software; you can redistribute it and/or modify it
       under  the  terms of the GNU General Public License as published by the
       Free Software Foundation; either version 2 of the License, or (at  your
       option) any later version.

       This  program  is  distributed  in the hope that it will be useful, but
       WITHOUT  ANY  WARRANTY;  without   even   the   implied   warranty   of
       General Public License for more details.

       You should have received a copy of the GNU General Public License along
       with this program; if not, write to the Free Software Foundation, Inc.,
       51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA