Greetings everyone,
Since the CASTLE mode transmission in Spectrum Lab seems to work now,
here is how to transmit it with just a soundcard (no DDS exciter
required). Of course your transmitter must support audio modulation
(USB), or use an I/Q modulator.
The new SpecLab version with CASTLE mode for the soundcard is here:
http://www.ssl7.com/dl4yhf/speclab/install_speclab_070104.zip
To switch to CASTLE mode, open the digimode terminal (from the main
menu: "View/Windows"..."Digimode Terminal". Then, in the digimode
terminal's menu, select
"Settings" .. "Predefined Modes" ... "Slow CW / DFCW / CASTLE" ... and
switch to one of the CASTLE modes (CASTLE 3, 10, 30, 60 ; where the
number is the symbol time in seconds ).
This sets the symbol time *and* the offset (= "shift" = frequency
difference between 2 tones) according to ZL1BPU's suggestion. But you
can alter them on the "Digimode Configuration", for example to make the
signal a bit narrower than suggested. The default shift for each tone is
8 divided by the symbol time; for example 8 / 3 seconds = 2.666 Hz . But
on Markus' grabber the CASTLE pattern was easily recognizeable with a
smaller shift, so this is something to play with. Especially in the
"inner-EU" 137.700 kHz window, a narrower shift should be used.
As Uwe already mentioned, the reference frequency (in SL: labelled "fTX"
= audio "transmit" frequency) is actually never transmitted. Morse
dashes are above that frequency, dots are below that frequency. The n-th
dash is n times the offset ABOVE the reference, the n-th dot is n times
BELOW the reference, etc.
The general usage of SL's digimode terminal is described in the manual
(how to enter text, how to switch to TX, etc).
Best regards and hpe cul,
73 Wolf DL4YHF .
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