Question

The range of a communication system can be extended by a

• A. modulator
• B. transmitter
• C. demodulator
• D. receiver
• E. repeater

Answer 1

The correct option is E repeater

In digital communication systems, a repeater is a device that receives a digital signal on an electromagnetic or optical transmission medium and regenerates the signal along the next leg of the medium. In electromagnetic media, repeaters overcome the $attenuation$ caused by free-space electromagnetic-field divergence or cable loss. A series of repeaters make possible the extension of a signal over a distance.

Repeaters remove the unwanted noise in an incoming signal. Unlike an analog signal, the original digital signal, even if weak or distorted, can be clearly perceived and restored. With analog transmission, signals are restrengthened with $amplifiers$ which unfortunately also amplify noise as well as information.