Hello David and LF-group,
where might this software be?
no lf in usa, but 160m can be a bear too !
david<
today, Markus, DF6NM and I have performed the first succesful 2-way LF QSO
in slow-voice. Markus used a software named Goldwave (don't know where that
can be found but Markus said it is shareware, so have a look in the
Internet search machines ...). I used Cool Edit 2000, that can be
downloaded at http://www.syntrillium.com (it is also shareware, the demo
version comes with two functions only, you need to register to have full
access to all features).
We started at 137.350 to 137.600, where Markus was able to read my signal
(8 times slower than normal voice) with 57. When I tried to receive him I
found that the 1.7 kHz filter that I use in my MV62 Level Meter was too
wide to prevent DCF39 from causing heavy QRM. The build-in 100 Hz filter is
too narrow for the 250 Hz bandwidth we used. The 250 Hz filter that I use
in the IC-746 that comes behind the level meter on 200 kHz is narrow
enough, but it comes too late, the band is already spoiled by the Burg
transmitter.
The solution was to move 500 Hz further down, with our transmission
spectrum situated between 136.850 and 137.100 kHz. I hope we did not cause
any inconvenience to anyone tranmitting there. We have accompagnied our
slow-voice transmissions with CW to steer the QSO. All in all it took about
2 1/2 hours to complete the QSO, whereby my report for Markus was 35,
however, in a later transmission I could read him better than that
(probably 45).
The QSO mainly too that long because I had to fiddle around with the
appropriate adjustments. For the transmission I used macros, so it took
only one or two minutes to be able to transmit a 3 minute over. For
reception I did not prepare anything and had to do some experimentation.
For future transmissions we will need to find another way or a better clear
spot, maybe even further reducing the bandwidt to 100 Hz and make use of
the narrow filter ...
I know that SSB QSOs have been performed in the band some years ago in the
U.K., but this slow-voice transmission helps us to
- overcome the bandwidth limitation in Germany (max. 800 Hz)
- helps to prevent QRM aking best use of the availabel spectrum
- increases the signal-to-noise ratio relative to the bandwidth used
- ... and is a lot of fun ... hearing the other's voice clearly readibly
despite the low signal strength!
I will post some further information on my website (http://www.qru.de).
So, a new field of experimentation. We will conduct further tests and
improve the operating procedures. Maybe someone who has fun programming the
Soundblaster card might want to develop a slow-voice software that allows
more-or-less realtime QSOs ...
Best 73, thanks to Markus, DF6NM for the nice experience, to Walter, DJ2LF
for his reception report and a very happy New Year 2001 to you all!
Geri, DK8KW (W1KW)
Slow-Voice data of the QSO today (December 31, 2000):
- transmitted audio bandwidth 300-2300 Hz (2000 Hz total bandwidth)
- speed: 8 times slower than the normal voice
- transmition mode: USB
- total radio frequency bandwidth 250 Hz with 300 Hz audio equal to the
lower frequency of the spectrum, 2300 Hz to the upper freqeuncy
- QSO control by CW in the middle of the spectrum used
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