Hi Tom,
I guess my objection is to taking a technical term that has a definition and
then simplifying without (as Ian ended up doing) ensuring that the
simplification and the situation of its applicability is spelled out.
Supposing that for some reason amateurs started using OFDM with M-ary QAM.
You could well end up on the low bands with the PEP existing for only one
cycle of RF; this certainly happens at the base band. Thus the definition is
generally correct, while the application allows latitude. But unless one
recognises that this latitude is not generally applicable, it easily leads
to misunderstanding.
Like bit freaks and 'bandwidth'!
For all practical purposes, the assumption for amateurs at the moment is
valid. And the fundamental power measurement as I think it was you that
said, is the bomb calorimeter. Can you see the sweep tube linears running
for long enough to reach thermal stability in the calorimeter??
Interestingly enough, for purposes of Type Approval, the European standards
allow a maximum measurement uncertainty to 95% confidence level of 1,5dB on
conducted RF power, which seems a big tolerance. However, the measurement
inaccuracy build up justifies this - just because the Bird is accurate to 5%
of FSD, it doesn't mean that the measurement over all is that good.
73
Peter G3RZP
--
FAQ on WWW: http://www.contesting.com/ampfaq.html
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|