Modulator

By: Engr. Syed Asad Ail

Communication

• Communication is the process of Exchanging Information

• Communication Can Be– Local– Remote– Verbal Or Non-Verbal

Communication system

1. Telephones

2. Radios

3. Television4. Computer Communication

– Email– Internet– Skype

COMMUNICATION MODEL

Modulation

• Process of Varying one of the characteristics of the High Frequency signal in accordance with the Information Signal.

• Device that this perform is known as Modulator• Characteristics

– Frequency, Amplitude and Phase

• Types1. Frequency Modulation

2. Amplitude Modulation

3. Phase Modulation

Example

Why Modulation

• Voice Signal has Low Frequency– Requires Large Antenna

• To Avoid Interference • To Cover Larger Distance

example

• The audio signals have relatively short wavelengths• The size of antenna should be at least λ/4,

= c/f

= 3x108/20000 = 15000

/ 4 = 3750m = 3.75 km 

This much size of antenna is practically impossible.

• If more than one station starts transmitting at the same AF (Audio Frequency) there would be a lot of interference.