>>Maybe what has confused you is the power sum of two tones is
>>NOT twice the original tone.
>>
>>For example in a two tone test the sum of the two equal tones is
>>six dB greater than a single tone, not 3 dB. That's why, if you look
>>at the ARRL IMD settings, they set the individual tones six dB
>>below the reference PEP to read IMD below PEP. PEP is not RSS,
>>or RMS.
OK, after looking at some textbooks, maybe I understand what you are
saying. I think you are talking about peak power here and I am talking
average power.
For n incoherent tones: Pavg = n*Ptone while Ppeak = n^2*Ptone (Solid
State Radio Engineering pg 509).
So for two tones, Pave = 2*Ptone and Ppeak = 4*Ptone
4 times a signal's power is the same as adding 6 dB.
So when speaking about the peak power, you are correct. I was talking
about average power.
73,
Jon
KE9NA
--------------------------------------------------------------------------
The Second Amendment is NOT about duck hunting!
Jon Ogden
jono@enteract.com
www.qsl.net/ke9na
"A life lived in fear is a life half lived."
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