Question

What is it called when the noise is present in the transmission line but gets canceled at the receiver?

(a) Cancellation mode

(b) Common mode cancellation

(c) Common mode rejection

(d) Rectification

I have been asked this question in unit test.

I want to ask this question from Transmission Line Basics in portion Transmission Lines of Avionics

Answer 1

Right answer is (c) Common mode rejection

To elaborate: When the noise affects the transmission, its effect is on both the wires but since they are 180° out of phase when the signal reaches the receiver the noise gets cancelled out. This is called common-mode rejection, and noise reduction can be as great as 60 to 70 dB.