Radio communication

Radio communication is the transmission of high frequency energy from the transmitter to the receiver without wires. Radio is a device that transmits and receives signals and programs by electromagnetic waves. Since the process of radio communication includes transmission and reception of signals, the two necessary components of radio are a transmitter and a receiver.

The first component of radio, the transmitter, is a device producing radio-frequency energy. The transmitter consists of a high-frequency oscillator including an oscillatory circuit (a coil and a capacitor) and one or more amplifiers. Electric oscillations are produced in the antenna of the transmitter. They travel in all directions. Electron lamps are used to amplify currents and give greater transmitting range and better reception.

Radio waves are electric waves of very high frequency; they travel through space at a speed of light, and differ from other wave forms only n frequency (number of vibrations per second).

The second important component of radio communication is the receiver, a device that receives waves sent out by a transmitter. Radio receiver demodulates these waves, and they are heard as speech, music or signals. To understand this process let us consider the principle of operation of these devices.

A microphone is connected to the circuit of the transmitting antenna. When we speak into the microphone its resistance varies with the audio frequency. An alternating current is established in the microphone and antenna circuits, and its frequency is the same as the audio frequency. Oscillations of the same frequency are induced in the antenna and the oscillatory circuit of a receiver. These oscillations are in fact a high-frequency current. In order to reproduce the transmitted sound, this current modulated by audio frequency should be sent through the telephone, and a detector or rectifier should be connected to the telephone circuit. The audio frequency rectified current passes through the telephone and produces oscillations. These oscillations will reproduce the sounds produced at the transmitting station. The operation of a radio set will be the better, the more energy is received by its oscillatory circuit. The oscillatory circuit is also provided with a ground. It is important for god operation of the receiver. The antenna should be grounded by means of a switch.

Internet radio, also known as web radio or net radio is an audio broadcasting service transmitted via the Internet. Internet radio services are usually accessible from anywhere in the world. This makes it popular among listeners with interests that are not adequately served by local radio stations. Internet radio services offer news, sorts, talk and various genres of music – everything that is available on traditional radio stations.

Communication systems and information theory

Communication theory deals primarily with systems for transmitting information from one point to another. The source output might represent a voice waveform, a sequence of binary digits from a magnetic tape, he output of a set of sensors in a space probe, or a target in a radar system. The channel might represent a telephone line, a high frequency radio link, a space communication link, or a storage medium.

As it is known, in the early 1940’s a mathematical theory for dealing more fundamental aspects of communication systems was developed. The distinguishing characteristics of this theory are, first, a great emphasis on the theory of probability and, second, a primary concern with the encoder and decoder, both in terms of their functional roles and in terms of their achieving a given level of performance. In the past 20 years, information theory has been made more precise, has been extended and brought to the point where it is being applied in practical communication systems.

Much of modern communication theory stems from works of communication systems as well as from desirability of modelling both signal and noise as random processes. N. Wiener was interested in finding the best linear filter to separate the signal from additive noise with a prescribed delay. His work had an important influence on subsequent research in modulation theory.

Information technology (IT) is the study, design, development, implementation, support or management of computer-based information systems, particularly software applications and computer hardware. Information technology deals mainly with the use of electronic computers and computer software to convert, store, protect, process, transmit and securely retrieve information.

Today the term information technology includes many aspects of computing and technology and covers many fields. Information technology professionals perform a variety of duties that range from installing applications to designing complex computer networks and information databases. The duties of IT specialists may involve data management, networking, engineering computer hardware, database and software design, as well as the management and administration of the whole system. When computer and communication technologies are combined, the result is information technology, or “infotech”. Information technology describes any technology that helps to produce, manipulate, store, communicate and/or disseminate information.

Thus, Information Communication Technology (ICT) embraces all technologies for the communication of information. It includes any medium to record information (paper, pen, magnetic disc / tape, optical discs – CD / DVD, flash memory, etc.) and technology for broadcasting information – radio, television. It involves any technology for communicating through voice and sound or images – microphone, camera, loudspeaker, and telephone. At present it is apparently culminating to information communication with the help of Personal Computers (PCs) networked through the Internet, information technology that can transfer information using satellite system or intercontinental cables.