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A signal travels through a transmission medium and its power is reduces to one...

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mzu786 | High School Teacher | eNotes Newbie

Posted January 13, 2011 at 1:05 PM via web

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A signal travels through a transmission medium and its power is reduces to one forth.  Calculate the attenuation.

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kjcdb8er | Teacher | (Level 1) Associate Educator

Posted January 19, 2011 at 10:20 AM (Answer #1)

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In optics, attenuation is related to the ratio of the input power to the output power of the signal. The equation for attenuation is:

Attenuation (dB) = 10 * log( input power / output power )

According to the problem statement, input power / output power = 1/4

Therefore,

Attenuation (dB) = 10 * log( input power / output power ) = 10 log( 1/4 ) = 10 * -0.6 = -6 dB.

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