Provided by: glfer_0.4.2-2build1_amd64 bug


       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

       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 changed.

   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: 1024)

       -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

       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 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
       See the GNU 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