[AMPS] PEP philosophy

[Ian White, G3SEK]

Fisher wrote:
>>
>> <For the FCC PEP rule, Part 97.3 defines PEP as "The average power
>supplied
>> to the antenna transmission line by a transmitter during one RF cycle at
>the
>> crest of the modulation envelope taken under normal operating
>conditions.">

>The problem to me is not that it is or is not picky - it is that I don't
>know what they mean.  Once I know what they mean, then I'll know if it is
>picky or not.  What do they mean?
>

The FCC quote is complete, accurate and consistent. It's also the same
definition as is used in the UK.

Just remember that the "Peak" in PEP means the peak of the *modulation*
- not the peak of the RF cycle.

Your RF power is always defined as the average over one complete RF
cycle (or several complete identical cycles). That's what the "RMS"
operation does.

The only difference with "PEP" is that it's saying, in effect: "Identify
the largest, most powerful RF cycle at any time in your transmission -
that's the one the power limit applies to."

For practical amateur modulation modes, the modulation frequency is
thousands to millions of times slower than the RF frequency. That means
that at even the crest of the modulation cycle, you have at least
several hundred RF cycles that are all pretty much the same, and the
definition of PEP applies to any or all of those cycles.

73 from Ian G3SEK          Editor, 'The VHF/UHF DX Book'
                          'In Practice' columnist for RadCom (RSGB)
                           http://www.ifwtech.demon.co.uk/g3sek

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