Topband: Digial mode spurious issues

[Tom W8JI]

> I have been using WSJT since 2001 and cringe every time I hear it called a 
> "QRP mode".

I want to put this to rest with just a few more comments.

While we call these digital modes, they are really baseband audio 
transmissions run through SSB transmitters. They are subject to all the 
dynamic range problems and limitations of SSB transmitters processing the 
same types of audio tones.

The usual "cure" offered for the poor or limited performance of the SSB 
systems that process the encoded audio is to turn the power down. That 
doesn't always work to eliminate problems, plus low power obviously limits 
the potential range.

This stuff is really all just an audio signal processed by a SSB rig. That's 
why it can go into the SSB transmitter! SSB transmitters are just not that 
good, and that is why these systems create adjacent channel problems and 
will always create problems. They should be off someplace out of the way of 
weak CW signals, not nestled up against weak signal CW areas. A receiver 
cannot filter out transmitter flaws, no matter what some might claim or 
imagine. If a spurious signal is right on top of a weak station, it is on 
top of it.

These are just the hard, cold, facts of life. It's just disappointing we 
have no technical people who think things through before picking frequencies 
for "new modes".

73 Tom