Today everyone is familiar with the term ‘radio’ because of the great aspect with which it has touched our lives. When we hear radio the first thing that comes to our mind is FM. Well this is not the only thing. There is much more to this concept. Radio is a type of wireless transmission.
– Radio is all about transmitting the signals along the free space without the use of wires.
– This is done using the electromagnetic radiations of certain frequencies.
– These frequencies lie below the frequency of the visible light.
– This range of frequency is called the radio frequency range and it ranges from 30 KHz up to 300 GHz.
– The waves thus generated have been termed as the radio waves.
– Oscillating electromagnetic fields serve as a means for transmitting the electromagnetic radiation passing through the space vacuum and air.
– Information in audio form is transmitted in the form of radiated waves whose some property is modulated i.e., systematically changed.
– The properties that might be modulated are frequency, phase and amplitude.
– When an electrical conductor is struck by the radio waves, an alternating current is induced in the conductor due to the oscillating fields.
– Thus, the information stored in the waves is extracted and converted in to the original form.
– Wireless is nothing but the radio telegraphy.
Elements of Radio System
Below we discuss about the elements that are a part of the radio systems:
Transmitter and Modulation:
– Transmitter acts as a source of electric power which is used in the production of alternating current with required oscillating frequency.
– A modulator is a device that is used for changing the property of the current so that a signal can be impressed up on it.
– This modulator resides in the transmitter itself.
– The modulated electrical waves are sent to a resonant antenna that is already kept tuned.
– The rapidly changing alternating current is converted in to electromagnetic waves that are capable of traversing through free space.
– This electrical device is responsible for the conversion of electric currents in to waves and also vice versa.
– It is installed in both the transmitter and the receiver.
– A little power of the electromagnetic wave is intercepted by the antenna during reception for generating a small terminal voltage.
– After generation, the waves travel through space directly.
– Therefore, various phenomena such as refraction, reflection and diffraction etc. might alter their paths.
– Because of the geometric dispersion the intensity of these waves tends to diminish and the medium might also absorb some energy.
– Also, the desired signal is very much altered by the noise from various natural sources and artificial sources (accidental radiators).
– The inherent properties of the devices being used might also give rise to noise.
– This property helps in the selection of the individual stations.
– This is so because a resonant circuit responds properly to only one frequency.
Receiver and Demodulation:
– The antenna catches the electromagnetic wave and also intercepts a little of its energy and transforms it in the oscillating electrical current.
– At this end demodulation of the EM signals occur.
– This conversion is performed by a circuit called the detector.
– It tunes the receiver to respond particularly to the signals that are desired and reject the others.
– Earlier, only the energy that antenna collected was used for the production of the signals.
– The transistor made the radio a more useful device since it helped in the amplification of the weak signals.
Today, radio systems find use in controlling of the space vehicles, walkie – talkie, broadcasting and so on.
Input to the receiver comes through the antenna after passing through the electronic filters. It is then amplified to a certain level at which it can be processed properly. The signals are decoded in to consumer usable form such as image, picture etc.