EE 164 Problem Set 3 Spring 2005 Problem 1: A source emitting two wavelengths(1λand2) is intensity modulated at frequencymf. The power at1is( )101111cosmPP Ptωφ=++. The power at2is( )202222cosmPPPt+. Find an expression for the total power. Now assume that1mf=kHz. At the receiver 01022Wµ==, 11221W. Plot1P,2P, and total power (as a function of time) if210−=. Repeat if1.57r−=. Repeat if3.14r−=. Plot the peak-to-peak value of AC power versus−. Problem 2: As noted in Section 3.1, the power in a light beam is proportional to the squarre of the its electric field and the electric field for a beam traveling in an attenuating medioim can be given by Eq (3.8). The attenuation coefficient in that equation determines the loss. On the other hand, we more frequently discuss the loss in temrs of decibels per kilometer.
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