Radio or Radio Data Systems (RDS) is a technology which works in conjunction with FM Radio (Frequency Modulation)
The radio station find on the dial between 540 kHz and 1600 kHz are known by three names:
AM (Amplitude Modulation)
AM referring to the method used to impose the program on carrier waves. 10 KHz channels are assigned for AM radio.
Referring to the portion of spectrum where it is found.
About 3000 KHz have been set aside in nine bands of the short wave portion of spectrum (3 MHz to 30 MHz) for long distant broadcasting
FM (Frequency Modulation)
200 KHz channels are assigned for FM radio. Frequency of FM carrier wave varies and it has capacity to carry approx. 20000 cycles per second of the sound which are audible for human ears.
While conventional radio broadcast on medium wave and shortwave bands have the advantage of larger service areas for a given radio station, but on the other hands it also leads to serve congestion of radio station of these bands.
To reduce this congestion, radio stations has forces to use the higher frequency bands for radio transmission. FM radio is a one of the examples of higher frequency bands. However it has certain limitations in terms of coverage area. Almost it can cover about 30 km radius. Therefore FM stations are ideal as local radio stations, as there can offer programs of local community interest, high fidelity music, local news etc. to the public.
Radio text or Radio Data Systems (RDS)
Radio text is to bees as the value added service on FM radio. In this technology, FM carrier waves consists transmitting data including textual material. The listener/ viewer having radio text ‘decoder’ can extract this signal from ongoing FM transmission and view on a computer screen. One can easily chose between any one of normal FM transmission or radio text. In addition, audio signal of speech quality can also be a part of radio text signal.
It is beneficial for those who like to get ‘audio lessons’ along with the simultaneous transmission of print material.
E.g. AIR (All India Radio) & Yashwantrao Chavan Maharasthra State Open University (Nasik) already initiated a joint venture in this regard.
Digital Audio Broadcasting (DAB)
Several broadcaster, including AIR, are to introduce DAB during next few years. DAB technology arose out of a European project called Eureka – 147. Broadcasting of this technology was launched in 1995 by BBC in London.
It transmit sound as computer code. Rather than the analog waves. Like computer disc (CD) technology it provides interference free sound.
Though primarily an audio medium, it can also carry multimedia services such as text data-files, graphics, picture and moving video. Thus DAB users can listen to music accompanied by information and pictures on their computer screen.
There are few other application of this technology like it can be used for tour and travel information to computer terminal, to transmit travel information or it can equipped a car with multimedia DAB receiver.