The three images above show
some examples of QRSS signals as they appear on the screen of a PC
running suitable audio spectrum analyzer software. In the first example
(above left)
Argo has
been used to display the QRSS signals, in the second example (above
center)
Spectran
has been used and in the third example (above right)
Spectrum Lab
has been used. Argo (by I2PHD) is perhaps the easiest to use and
recommended for those who are new to
QRSS, Spectran (also by I2PHD) is slightly more complex but offers
additional features not found in Argo. Spectran is very versatile and can
be used for other modes and applications. Spectrum Lab (By DL4YHF) is a
very professional package and can also be
used to generate tones and complex signals making it suitable for QRSS
TX applications. This would be the package of choice for those wanting
to generate the more "exotic" QRSS modes.
In each of the examples above the software performs the FFT described
earlier and presents the user with a display of frequency
(vertical axis) with respect to time (horizontal axis), the display
scrolls horizontally so that the results can be observed over an
extended period of time. Typically, the display will be set-up to show
just over 100 Hz of the received audio bandwidth containing the QRSS
signals. This 100 Hz window is user definable in all cases. In the case
of a CW carrier you might expect to see a straight white line running
horizontally across the screen, if the signal is frequency shift keyed
(FSK) then you may expect to see FSK encoded Morse characters or
patterns similar to the examples shown above. Receiving equipment for
QRSS must have exceptionally good frequency stability to be effective.
A more
in-depth discussion about the hardware/software requirements for
successfully receiving QRSS and links to suitable QRSS receiving
equipment projects can be found here.
Receiving QRSS