Bill's information is entirely correct. Thank you for that clear
explanation.
Now back to what I think was the intent of the original question - even
if the terms were incorrect.
Hams commonly use two different considerations for power - PEP - Peak
Envelope Power - that is the peak power that we (at least here in the
US) need to use when considering our power limits, and that is the
specified power output for most if not all amateur transceivers and
amplifiers.
The other term is Average Power, and we can use that for a measure of
the amount of compression used in SSB transmissions - more compression
will bring the Average Power up closer to the PEP, but too much will
create muffled speech (listen during a SSB contest for the
unintelligible signals using too much compression).
As Alan Bloom indicated, the narrow bar indicates the PEP value, while
the other bar will be more of an indication of Average Power, although
your eyes may have to interpret the movement to determine the real
average because that indicator will be constantly changing with SSB
speech patterns, but for CW and data modes, the PEP and average should
be equal during keydown intervals.
73,
Don W3FPR
On 8/21/2015 3:34 PM, Bill Breeden wrote:
It's important to remember that RF power expressed in watts is always
based on RMS values. If RF watts are calculated by measuring the
voltage across a known load, the voltage must be expressed as an RMS
value to correctly calculate the power in watts. Watts are watts.
There is no such thing as "peak to peak" or "RMS watts" when
expressing RF power in watts.
Peak envelope power (PEP) has nothing to do with the difference
between the peak and average voltage of a sine wave. It is the
measure of the power of an RF signal at the modulation peak, averaged
over one RF cycle. The power measurement within that one RF cycle is
still based on RMS values.
73,
Bill - NA5DX
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