[Elecraft] SSB - Fooie!

[Ron D'Eau Claire]

George, W5YR wrote:

I don't know where the 20 dB advantage figure for CW over SSB comes
from, but both Larry and I were around during the early days of the
AM/SSB wars. A number of analysis papers were published in all the ham
literature, but as I recall the consensus was that sideband offered an
overall 9 dB over DSB AM in terms of S/N and some intangibles like power
consumption, final amplifier efficiency, etc....

--------------------------

Ha! I had forgotten about the equations that included the final
amplifier efficiency (or supposed efficiency) back when virtually no Ham
had much of an idea how much power the rig put OUT, but only how much
power the final amplifiers CONSUMED!   Your age is showing <G>.

You are perfectly right, George. The advantage of one mode over another
is basically a difference in bandwidths, assuming no interference. What
is a workable bandwidth for any mode is largely up to the operator's
tastes. Some ops hate the sound of SSB with less than 3 kHz of audio
bandwidth. Others like 2 kHz. Some ops run their CW rigs at 200 Hz or so
bandwidth. Others (including me) tend to use 1 or ever 1.5 kHz unless
QRM forces me to narrow down the bandwidth. 

Another variable with voice vs. CW is the fact that you must hear MORE
of the SSB to make sense of what is being said. With CW, you can QRS and
make out what is going on with very weak signals. There is a higher
degree of  redundancy in the CW signal that allows more data to be lost
before the meaning is lost than with a voice. While it is theoretically
possible to hold a SSB QSO in which the stations spell every word
phonetically and repeat them, I suspect that it's a lot more common for
a CW operator to QSZ automatically when conditions are bad. 

So the dB "advantage" of one mode over another includes a lot of
subjective operator choices. 

If one wants an "absolute" statement that holds up under any conditions,
it is that CW can be read more easily by a skilled operator than SSB
under weak signal conditions. Beyond that it's a debate!

That said, I am not suggesting that it isn't possible to hold an SSB QSO
spanning the earth with a few milliwatts of RF. I am suggesting that it
will happen more often with a narrower-bandwidth mode like CW. Nothing
more.

Ron AC7AC
K2 # 1289