From: "Mike Dennison" <mike.dennison@rsgb.org.uk>
To: rsgb_lf_group@blacksheep.org
Date: Thu, 1 Jun 2000 16:08:23 +0100
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Subject: Re: LF: Slow CW vs. BPSK etc.
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> When you say "machine" modes, are you meaning CW decoded by software or by
> the brain (be it aurally or visually) ? There is a profound difference...
> 73, Alberto    I2PHD

This is all-important. Extremely weak stations require considerable 
additional work by the 'computer between the ears' to decipher 
what is signal and what is noise on the screen - just like aural 
Morse, but visual. This accounts for several extra dB of gain, and 
however slow you send the Morse, this advantage is still available. 
It would take a very sophisticated computer to be as good. 

There are, of course, advantages in having modes with little or no 
manual intervention. Suppose, for instance, it were possible to 
monitor for a transatlantic beacon and raise an alarm when a 
callsign (or some pattern) was recognised by the computer. This 
may be where BPSK comes into its own as being superior other 
purely machine-read modes.


Mike, G3XDV (IO91VT)
http://www.dennison.demon.co.uk/activity.htm