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Date: Fri, 05 Jan 2007 12:03:54 +0100
From: Wolf DL4YHF <dl4yhf@freenet.de>
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To:  rsgb_lf_group@blacksheep.org
Subject: LF: How to send CASTLE mode with SpecLab
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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 .