From: "Mike Dennison" <mike.dennison@rsgb.org.uk>
To: rsgb_lf_group@blacksheep.org
Date: Wed, 21 Mar 2001 12:30:32 -0000
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Subject: LF: WOLF - Transmit?
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Ok, so having cracked the receive side, how do I transmit WOLF?

As I understand it there are three methods:

1 - Audio from the soundcard is fed into a 136kHz SSB transmitter, including 
of course an HF SSB Tx with a transverter. Presumably the transmission is 
independent of which sideband is selected.

2 - Audio from the soundcard can be combined with the 'VFO' in an XOR gate 
and fed into an amplifier - presumably linear. This looks useful to me as I have 
a 200W linear amp.

3 - The M0BMU method that allows the use of a non-linear Class D Tx. How 
and why does this work?

All three methods are potentially simple, but are made complex by the need for 
very careful bandwidth tailoring to keep the transmission to about 20Hz wide. 

Have I got any of this wrong? Is there anything published on the subject? 
What is in use? 

I understand that some Lowfers have used WOLF, but I suspect that 
bandwidth has not been an issue because of the total width of the allocation 
and the low ERP. I believe that Larry, VA3LK, has transmitted WOLF, but 
again perhaps the bandwidth was not a problem. Jim, will you publish your 
circuits? Or perhaps they are rig specific?

It appears relatively easy to get going on receive but practical transmit has an 
information black hole.

Advice, please.


Mike, G3XDV (IO91VT)
http://www.lf.thersgb.net