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DSB power


yousef_ob
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hello,
in the attached equation m(t) is a power signal - not an energy signal. we know that DSB modulation is defined by the equation m(t) cos (2*pi * fc*t). so that the power of this signal is the integration of the sequared equation over the period - i.e power = integration over period of (m(t) cos(2*pi* fc*t)^2. we know that cos^2(wc*t)= .5(1+ cos(2*wc*t))
then multiply this by m^2(t) and integrate over the period, then the first term in 0.5 * the power of the mudulating signal (m(t)). and the second term is zero i am asking why it is zero. i gonna attatch the equation again

post-7378-14279142465796_thumb.jpg

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  • 2 weeks later...

Hi Yousef,
I haven't looked at math like that for about 40 years but I'll try answering your question.
It looks like it is calculating average suppressed-carrier (?) DSB AM modulated power. I think the 2nd part of the equasion is zero because it is the minimum power and the 1st part is the peak power. ;D

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