RADIO BROADCASTING: Broadcasting system is a chain of technically / electronically coupled elements which is used to pick up an ordinary sound wave, convert it to an electrical wave (of some frequency say from 50Hz to 10 Khz) without any change in its parameters. This sound wave is fed to a radio transmitter where its frequency is again raised by combining it to third wave of a higher frequency called the radio frequency. This is the frequency which is allotted to a particular station (in Pakistan a Frequency Allocation Board (FAB) allotted a frequency). This is called the carrier frequency while the wave of the second frequency is called the audio wave. The audio and carrier waves are combined electronically through a process called Modulation. This important process takes place in a radio transmitter. Further this modulated wave is fed to an antenna which radiates this wave in the form of an electro magnetic energy. Following diagram shows how to broadcast
CONTENTS: Contents means the script or things which are transmitted. Contents are the main theme of the radio, without content radio is empty. A host or DJ plays his role to convey the contents and play the songs, etc.
PRODUCE: Produce is the process of producing the voice, sounds etc from the audio mixer which mostly handled by the DJ or host himself. The mixer mix the voice and the sound from the device and send it to the Modulation process
MODULATION: It is the process where audio and carrier waves are combined electronically.
AMPLIFICATION: An amplifier is any device that changes, usually increases, the amplitude of a signal. The relationship of the input to the output of an amplifier, usually expressed as a function of the input frequency, is called the transfer function of the amplifier, and the magnitude of the transfer function is termed the gain.
EMISSION: It is the radiation or radio signal produced or emitted by a radio transmitting station.
REVEIVER: It is a device which gives the output of the whole process. In other words it is a receiver which receives the signals and deliver the output to the listeners. This is called radio receiver.
It is the process of varying one waveform in relation to another waveform. In telecommunications, modulation is used to convey a message. The three key parameters of a sine wave are its amplitude (“volume”), its phase (“timing”) and its frequency (“pitch”), all of which can be modified in accordance with a low frequency information signal to obtain the modulated signal.
There are three basic modes of modulation:-
Amplitude modulation (AM)
Frequency modulation (FM)
Phase modulation (PM)
AMPLITUDE MODULATION (AM): Amplitude Modulation (AM) is a technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. It works by varying the strength of the transmitted signal in relation to the information being sent. If the amplitudes of the two waves become equal to each other, the modulation is called 100%. By using the method of modulation generally called AM we can transmit our programmers in two ways:-
(i) Medium Wave transmissions which range from 645KHz to 1605KHz. This is called AM broadcast band
(ii) Short Wave transmissions which range from 3 MHz to 30 MHz.
The frequencies of the Medium Waves are low, and hence their range of services is also small. However, this range of services depends upon the power of the transmitter. The greater the power, the greater the service area, such transmitters are normally meant for Home/National or Regional services.
The frequencies of Short Waves are high and unlike medium waves, as soon as these waves leave the transmitting antenna take dominantly the form of sky waves and this can cover distant target areas and such radio transmitters assume the form of international stations.
FREQUENCY MODULATION (FM):
In system where the signal alters systematically the frequency rather than the amplitude of the carrier wave, signal transmission can be effected with a substantial lowering in the relative level of all types of interference. FM is commonly used at VHF radio frequencies for high-fidelity broadcasts of music and speech. A narrow band form is used for voice communications in commercial and amateur radio settings. The type of FM used in broadcast is generally called wide-FM, or W-FM. In two-way radio, narrowband narrow-fm (N-FM) is used to conserve bandwidth. In addition, it is used to send signals into space.
PHASE MODULATION (PM):
Phase modulation (PM) is a form of modulation that represents information as variations in the instantaneous phase of a carrier wave.
Unlike its more popular counterpart, frequency modulation (FM), PM is not very widely used. This is because it tends to require more complex receiving hardware and there can be ambiguity problems in determining whether, for example, the signal has changed phase by +180° or -180°
History:- The concept of copyright originates with the Statute of Anne (1710) in Britain. It established the author of a work as the owner of the right to copy that work and the concept of a fixed term for that copyright. The Statute of Anne was the first real copyright act, and gave the authors rights for a fixed period, a fourteen year term for all works published the Statute, after which the copyright expired.
Copyright Act:- In 1790 US Congress passed an act for the encouragement of learning by securing copies of maps, charts, and books to the authors and proprietors of such copies “To promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries”
Copyright Act in Pakistan:- In Pakistan, copyright protection is governed by the provisions of the Copyright Ordinance, 1962 (“the Ordinance”) which is modeled on the English Act of 1914. Pakistan is a member of Berne Copyright Union and the Universal Copyright Convention.
One of the most significant developments in relation to the protection of copyright in Pakistan is the recent promulgation of the Copyright (Amendment) Act, 1992 (“the Amendment Act”). Copyright protection originally available to literary, dramatic, musical, artistic, cinematographic and architectural works, books, photographs, newspapers, engravings, lectures, records (defined as “any disc, tape, wire, perforated roll or other device in which sounds are embodied so as to be capable of being reproduced therefrom, other than a sound track associated with a cinematographic work”) and sculptures is now extended to computer software, periodicals, video films and all kind of audio-visual works.