§97.3(b)(6): 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. That can be captured on a scope. Whether it is composed of the carrier, either or both sidebands, or any combination thereof is mostly unimportant. It is only necessary to capture one RF cycle at the crest of the modulation envelope taken under normal operating conditions.
They do say average, not RMS. Thank goodness they don't ask enginers to measure the RMS power of that single cycle because any distortion would cause a conniption fit since there is a condition of modulation, that RF cycle is not a sine wave bit it is distorted by the audio wave, albeit only slightly.
for 50 ohms:
774.5V peak to peak
387.25V peak
273.8V RMS
5.476A RMS
1500W RMS
It seems to get worse, BTW if taken literally. or does it?
The average voltage of a sinusoidal waveform is equal to 0.637 times its peak value.
387.25V peak
246.7V Avg.
4.934A Avg.
1217 watts Avg.
(1217 * 1.233 = 1500, so if this were converted to RMS it would allow 1500 * 1.233 = 1848 watts RMS in that RF cycle at the crest of the modulation envelope)
However, note: The average voltage is normally determined from just one half-cycle of the waveform because the average value of a full cycle is zero. But the FCC requires it to be measured over the full cycle.
(source:
http://www.free-ed.net/sweethaven/ModElec/acee/lessonMain.asp?iNum=0102 )
Therefore taking §97.3(b)(6) literally:
PEP power = "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 average voltage supplied to the antenna transmission line by a transmitter during one
(complete) RF cycle at the crest of the modulation envelope taken under normal operating conditions is always zero
-except for the small amount of distortion present in the wave (it is not a perfect sine due to the modulation and PA distortion as well as any E I phase issues due to reactance in the load).
Therefore the average current 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 is always approx. zero.
Therefore 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 is always approx. zero.
Therefore
Any attempt to measure the average power by summing all the voltage and/or current points along the one RF cycle under normal operating conditions results in a value very, very close to zero.
The following corrolary is that the emissions limited to 1500 watts of actual power are the distortion+noise products contained in the cycle of RF supplied to the antenna that are derived from an unsymmetrical distribution of voltage points between the positive and negative half-cycles of the one RF wave.
Assuming a perfect load and the transmitter's power as measured by the method of §97.3(b)(6) to be 40db down (minimum standard for good practice?) from the transmitter's RMS PEP level which is not regulated, the RMS PEP wattage present when 1500W average power was measured would be 18,480,000 watts.
So, any more problems to be solved tonight?
(I also believe this would stand up to the FCC as well as the fellow's claim that he does not have to pay income tax stands up to the IRS.)
