[Amps] Measuring RF Power

[G3rzp@aol.com]

In a message dated 22/03/2005 22:54:13 GMT Standard Time,  
garyschafer at comcast.net writes:

Reading  the FCC definition of PEP it goes something like:
Peak envelope power is  the AVERAGE power in one RF cycle at the crest of 
the modulation  envelope.



It is actually the ITU definition - if I recall, CCIR Recommendation 321,  
it's so old!
 
Now, what is peak power?
 
In a radar, it's the power delivered during the pulse - so if you like,  it's 
the average power over the pulse. Or is it? What if the pulse isn't  constant 
power? Same applies when you send fast dots as aopposed to slow dashes  when 
tuning the amplifier. 
 
So 'peak power' isn't very helpful. To my mind, PEP is the most useful: you  
can apply it to a CW - the ratio of average power to PEP is then one - and 
it's  thus modulation independent. Incidentally, this discussion appears 
occasionally  in professional standardisation and regulatory circles, and causes just 
as much  (if not more) dissent than here!
 
The whole business of mixing the terms 'peak', 'average' 'rms' and finally  
'music' powers came from the audiophool industry, and has regrettably crept  
across.
 
73
 
Peter G3RZP