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Radio


What is a Radio?

A radio is transmission of signals where no wires are required, and which uses the modulation of electromagnetic waves with frequencies below that of visible light. Although it was Nikola Tesla who first demonstrated the feasibility of wireless communications in 1893, Guglielmo Marconi, an Italian inventor, was the first to develop workable radio communication. In Italy, he sent and received his first radio signal in the year 1895. Lots of experiments were carried out with the radio, but it was in the early 1930s that amateur radio operators invented single sideband and frequency modulation.

In 1954, Regency introduced a pocket transistor radio, the TR-1, powered by a 'standard 22.5 V battery'. However in 1960, Sony introduced its first transistorized radio, which was small enough to fit in a vest pocket, and was powered by a small battery. Over the next 20 years, except for very high-power uses, transistors replaced tubes almost completely. In the early 1990s, amateur radio experimenters were using personal computers with audio cards to process radio signals, and in the year 1994, the US Army launched an aggressive, successful project to construct a software radio that was to become a different radio on the fly by changing software.


Radio Broadcasting

Radio broadcasting is the distribution of audio signals that transmit programs to an audience. There are wide varieties of broadcasting systems, all of which have different capabilities. It can vary from limited area coverage to national coverage, and can be used to transmit signals globally too, using retransmitted towers, satellite systems, and cable distribution. Satellite radio revolutionaries the entire scenario, it could cover even wider areas, such as entire continents, and Internet channels can distribute text or streamed music worldwide. In the late 1990s, digital transmissions began to be applied to broadcasting.

 

A broadcast may be distributed through several physical means. If coming directly from the studio at a single station, then it is simply sent to the transmitter from the antenna on the tower. Programming which comes through a satellite, is played either live or recorded for transmission later. Different stations may simulcast the same programming at the same time. Usually, analog or digital tapes or CDs/DVDs are included in another broadcast. The final stage of broadcasting is to get the signal to the audiences. It is done via a station to a receiver or through cable. Internet also brings radio to the recipient.


Internet Radio

Internet radio is an audio broadcasting service transmitted via the Internet. Broadcasting on the Internet is usually referred to as web casting since it is not transmitted broadly through wireless means, but is delivered over the World Wide Web. Internet radio is usually accessible from anywhere in the world. These live radio stations on the Web make it a popular service since everything that is on the radio station is simulcast over the Internet with a net cast stream.

 

Commercial interests of corporate giants have proven to be a boon to listeners all over the world. I wish this continues and we all benefit from this, at least once for the sake of history, common man will be benefited by war of these big commercial giants. I fancy the day when telepathy will become so strong that we will not require any physical means to communicate, no words―just complete silence and peace and that every one will become a transmitter and a receiver. The rate at which we have grown in past few centuries―who knows someday all our fancies may come true.

 

Radio Frequencies
Radio frequency waves are high frequency waves. This technology finds uses in various fields. Radio frequency or RF is a frequency or rate of oscillation in the range of 3 Hz to 300 Ghz. This range relates to the frequency of alternating current signals to create and detect radio waves. As this range is beyond the vibration rate that many mechanical systems respond to, RF refers to oscillations in electrical circuits. When the current is passed through an antenna, an electromagnetic field is generated that is suitable for wireless broadcasting and/or communication. These frequencies cover the electromagnetic radiation spectrum ranging from 9 kHz, the lowest allocated wireless communications frequency, to thousands of gigahertz. When an RF current is passed through an antenna, an electromagnetic field is created that propagates through space.

 

Properties of Radio Frequency Electrical Signals

They can be ionized easily to create a conductive path across air
The electromagnetic force that drives the RF current to the surface of conductors known as skin effect
They have the ability to appear to flow through paths containing insulating material similar to the dielectric insulator of the capacitor


Radio spectrum
Extremely low frequency - 3 to 30 Hz
Super low frequency - 30 to 300 Hz
Ultra low frequency - 300 Hz to 3 Khz
Very low frequency - 3 Khz to 30 Khz
Low frequency - 30 Khz to 300 Khz
Medium frequency - 300 Khz to 3 Mhz
High frequency - 3 Mhz to 30 Mhz
Very high frequency - 30 Mhz to 300 Mhz
Ultra high frequency - 300 Mhz to 3 Ghz
Super high frequency - 3 Ghz to 30 Ghz
Extremely high frequency - 30 Ghz to 300 Ghz


Radio Frequency Encoding
These techniques physically encapsulate an RF encodable microchip with the synthesis resin. The RF transponder can be scanned post-synthesis to identify the concerned product. RF encoding avoids the need to cosynthesize surrogate analytes, and permits the large-scale synthesis of compounds; each microcapsule can hold tens milligrams of synthesis beads.


Radio Frequency Identification
This is an automatic identification method. RFID tags or transponders are used for storing and remotely retrieving data. An RFID tag is an object that can be applied in a product, animal or person to help in its identification using radiowaves. Some tags can be read beyond the line of sight of the reader. These tags consist of two parts. One is an integrated circuit for storing and processing information, modulating and demodulating signals, and for other specialized functions. The second is an antenna used for receiving and transmitting the signal. Chipless RFID discretely identifies tags in the absence of an integrated circuit. So, tags are printed directly on assets, and this helps lower its production cost.


RFID Tag Types

The various types of tags are as follows:
Passive : There is no internal power supply. The practical read distances range from 10 cm to a few meters, depending on the selected radio frequency and antenna design/size
Active : There is an internal power source. The range is of hundreds of meters, and the battery life is about 10 years
Semi-passive : They have their own power source. The battery powers the microchip, and cannot broadcast any signal


Use of RFID technology
RFID chips for animals are very small devices injected through a syringe under the skin
Real-time inventory tracking allows companies to control supply
RFID systems are used in some hospitals to track a patient's location, doctors, and nurses
Traffic monitoring system uses roadside readers to collect signals from transponders


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