I ran Spectrogram to view the part of the band
that Geri was transmitting in and got this excellent copy at the start of the
Later on the noise came up a bit and made things less clear but still copyable.
Here is Geri's reception of my
It was also nice to get a report from Ko Versteeg, his screenshot of my signal
I shall have to find out what settings he used to
get the very clear copy. You can tell my old IC735 is drifting LF as the
message slopes down!
My TX power was about 600W PEP
with the antenna in its low (15mtrs high) position due to bad weather. The WAV
files producing the text were generated by Markus DF6NM's Qbasic program and
played out via the soundcard to the IC735 which has been modified to produce a
small amount of RF at 136kHz from the transverter socket. This is then
amplified to about 5W by a TDA2030 audio chip which drives the usual Mosfet PA
biassed into "linear" mode.
Geri kindly translated the
instructions for use of the software into English so that I could set it up. It
worked first time, once I'd found an old copy of QBasic!
The bandwidth of the signal as
seen here was about 10Hz although this can be altered when the WAV files are
Thanks to DF6NM and
Have a go yourself.
software and unzip it into a folder called C:\Hell then you won't have
to edit any of the files. There's a readme in there with all the info. (not for
those frightened of DOS!)
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