Too many people are preoccupied with RF power; i.e, WATTS. What they don't
realize is that the MODE of operation is far more important than power...

AM (Amplitude Modulation) is composed of three parts: The carrier, the lower
sideband and the upper sideband. The carrier stays constant while the sidebands
vary in power according to the modulation. When a 4 watt carrier is modulated to
100%, there will be 1 watt transmitted in each sideband, for a total of 6 watts
of RF power that is being transmitted. But the voice can't modulate the carrier
to 100% all the time -- speech does not have a constant amplitude. Average
modulation is usually somewhere around 30%, so the average RF power that is
transmitted is closer to 4.6 watts.

Now AM works fine if you don't mind wasting power. This is because the audio is
carried only in the sidebands, not the carrier. And because the two sidebands
are mirror images of themselves, only one sideband is needed and the other is
wasted. If we eliminate the carrier and one sideband (resulting in the mode
called Single Sideband, or SSB), we are left with a 1 watt sideband that will
work just as well as if we burned 6 watts to transmit two sidebands and a
carrier. In other words, SSB is -AT LEAST- 6 times more efficient than AM. But
remember that average modulation is more like 30%, which means that a 0.3 watt
SSB transmission has the same effect as using 4.6 watts to transmit that very
same sideband using AM. Therefore, with normal speech, SSB is closer to 15 times
more efficient!

Let's translate all this into watts. CB permits 12 watts for SSB. For speech
communication, the average power is the same as the average modulation, or about
30%. So using voice on SSB the average power will be about 4 watts. Now since we
already know that SSB modulated with normal speech is 15 times more efficient
than AM. Therefore, 4 watts of SSB is equivalent to 60 watts of AM power, or 52
watts of carrier power with 4 watts in each sideband. And under 100% modulation
the SSB power will be 12 watts, while it takes 72 watts to do the same job on AM
(48 watts of carrier with 12 watts in each sideband).

But SSB has another advantage: Because it only uses one sideband, it uses half
the bandwidth of AM (6 KHz for AM vs 3 KHz for SSB). That means it receives half
the noise of AM, thereby doubling the all-important signal-to-noise ratio, and
effectively doubling the power of the transmitted signal.

All summed up, a stock CB with SSB has the same range and talk-power as the same
CB using AM with a 100 watt linear -- and it's LEGAL!





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