[AMRadio] PEP for AM |
D. Chester
k4kyv at charter.net
Sat Dec 30 12:33:15 EST 2006
---- Original Message ----- From: "Gary Schafer" <garyschafer at comcast.net> >> -----Original Message----- >> Subject: [AMRadio] PEP for AM >> Anyway, I ran across this information, and thought I'd share it with the >> group here, so that some mis-conceptions about AM PEP could be cleared >> up. >> >> (from: http://www.pc-oscilloscopes.com/articles/pc_oscilloscope_rf.html) >> >> P E P (AM) >> % Modulation = (( PEP - PC) / PC) *100% >> >> Example: >> Carrier Power PC = 100 W, PEP = 400 W. >> >> Determine % Modulation >> M% = (( 400 - 100) / 100) *100% = ((20-10) / 10) *100% = 100% > Hmmm, let's see, 400 watts -100 watts = 300 watts. Divided by 100 watts = > 3. > Times 100% = 300% modulation.. > > I think they forgot the square root of the powers in the formula. Looks like that may add to the misconception. But I'm not sure they left out the square root symbol. Could that be the reason for the double parentheses on the left? Since most word processing programs do not have easy access to mathematical symbols, and e-mail programs may not have them at all, a special set of symbols has evolved for mathematical expressions. I am not totally familiar with them, and I sometimes get totally lost when trying to interpret mathematical expressions posted over the internet. Isn't this what the formula is supposed to look like? (the problem is that it may not display correctly if your e-mail reader does not support Unicode). ____ ___ ___ % Modulation = ( √PEP - √PC ) / (√PC) *100% Evidently "they" think that so few people would have a use for mathematical formulae that maths symbols are not included in the default character set. Just like the ricebox manufacturers who no longer include monitor scopes in their appliance product line. Don k4kyv
This page last updated 16 Dec 2017.