Question

An input power of P = 3 W is fed to a 75 km conductor. A repeater is present at 40 km from transmitter and has a gain of 70 dB. The conductor has a of 3 dB/km. The power received at receiver side is: (a) -140.23 dBm (b) -120.23 dBm (C) -110.23 dBm (d) -150.23 dBm​

Answer 1

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Answer 2

Power received at the receiver side is - 115.23dB

We are given initial power 3W and the total length of the given conductor that is 75km, a for the conductor is 3dB/km

Also, it is mentioned that a repeater is placed at a position 40km from the transmitter having a gain of 70dB.

we need to find power till 40km length of the line and the formula used will be

Pf= 10log(Pin) - a×L

here Pf is final power, Pin is initial power of the conductor

P(at 40km) = 10log(3) - 3×40

P(at 40km) = -115.228dB

The power received at receiver side will be -115.228dB