What is a Digital Radio

A digital radio is an electronic device that uses a combination of analog and digital circuitry to transmit a number of signals on a single frequency channel using the technique of time division multiplexing. It is very much analogous to time division multiplexing used in the cellular GSM systems.

A traditional radio system uses either analog or frequency modulation for the transmission of the signal through the electromagnetic media. This modulated signal is then caught by the antennas on the receiver side where it is demodulated to form the original electric signal which then drives the speaker for the sound output. Thus in this system only one signal can be transmitted on a single frequency channel.

In digital radio, a number of signals are first converted in to digital form using Pulse Code Modulation or any other coding technique. These signals are then multiplexed in to a single signal using a time division multiplexing signal. This digital multiplexed signal can then be transmitted to the receiver either using an optical transmission system or through the traditional electromagnetic media by using an appropriate shift keying technique.

On the receiver side, the signal is first demodulated and then its demultiplexing takes place to separate the digital signals present in the original time division multiplexed signal in to separate channels. These digital signals can then be decoded to form the original analog signals. Thus the user receives a number of different signals on a single digital radio frequency and is provided with the option to select any of these signals which will then derive the speaker to give the desired sound output.

Some of the advantages of using this system over the analog radio system are:-

Less transmission losses because digital signals are less affected by noise. Long Distance transmission using a single tower. A single tower in this system can cover an area of approximately of 800 km. radius. Advanced signal processing techniques can be used to provide high quality output Though initial cost of installation will be high but the maintenance cost is lower than the analog system.

Less power consumption on both the receiver and transmitter side and also less power dissipation because of absence of inductors.

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