1.Antenna Length: To transmit a web correctly, the length of the trans-meeting antenna must be equal to the wave length.
Wave Length,
λ = Velocity of light/Frequency in Hz = 3 × 10^8/F
Transmitting a signal prior to modulation requires many, long antenna lengths, which are impractical to deploy.
Eg: Length of antenna for transmitting a signal of 20 KHz, λ = 15000 m. which is impossible to establish.
2.Operating range: The quality of the signal depends on the frequency of the operating range.If higher frequencies can be generated, the operating range of the signal increases.
So modulation is necessary to increase the operating range.
3.Wireless communication: In case of radio transmission, the signal is transmitted by means of radiation.For audio frequencies, the radiation method cannot be applied because the efficiency of this method is very low.So modulation is used in wireless communication.
Reasons for modulation:
- To increase the operating range of the signal
- To reduce antenna length
- For generating high frequency signals in wireless systems
- To protect the privacy of radio communications
- To increase channel or station
- Adjustment of Bandwidth
- Space Propagation