A transmission channel between two communicating DTEs is made up of three sections. The first introduces an attenuation of 16 dB, the second introduces an amplification of 20 dB, and the third introduces an attenuation of 10 dB. Assuming a mean transmitted power level of 400 mW, determine the mean output power level of the channel. (3 points)

the mean output power level of the channel is 100.475 mW

Explanation:

Given the data in the question;

for the first section; attenuation

16 = 10log₁₀  400/P₂

P₂ = 10.0475 mW

For the second section;  amplification

20 = 10log₁₀  p₂/10.0475

p₂ = 1004.75 mW

For the third section; attenuation

10 = 10log₁₀  p₂/1004.75  

p₂ = 100.475 mW

i.e the mean output power level is 100.475 mW

or better still overall attenuation channel = ( 16 - 20) + 10 = 6dB

so

6 = 10log₁₀  400/P₂

p₂ = 100.475 mV

the mean output power level of the channel is 100.475 mW