[Elecraft] PSK31 -- ghost image:

[Julian (G4ILO)]

Many sound cards have sound "enhancement" features intended to give a 
pseudo-3D effect and suchlike. On some of the cheaper ones it may not be 
possible to turn this off. I've never encountered this myself but I've read 
about it. Goodness knows how they go about creating these effects but I 
can't imagine it does much good to a PSK signal. On top of that, the 
average sound card is not a high quality product and the A-D conversion may 
be anything but linear. Either of these things could be the cause of 
"ghosts" on the transmitted signal, even if the user has correctly adjusted 
the level, as well as on the received signal.

The only real way to tell if you are in the clear is to transmit into a 
dummy load and monitor yourself. I did that once, and was impressed at how 
clean the K2 was. However I no longer have a second ham receiver so it is 
no longer possible. For most people, I guess, the difficulty in doing this 
will be not having a second computer.

73,
--
Julian, G4ILO. (RSGB, ARRL, G-QRP, K2 #392)
G4ILO's Shack: http://www.qsl.net/g4ilo

Rich Lentz wrote:

I will agree that when you overdrive the transmitter you will produce =
ghosts
and all kind of other spurious signals. But, if the person(s) =
transmitting
causes all the "ghost(s)" that I observe how does that explain my
observations.