RADIO (1)

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WELCOME
BY HEERA GEORGE
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RADIO
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• Radio is the radiation (wireless transmission)
  of electromagnetic energy through space.
• The biggest use of radio waves is to carry
  information, such as sound, by systematically
  changing (modulating) some property of the
  radiated waves, such as their amplitude,
  frequency, phase, or pulse width.
• Today, radio takes many forms which includes
  wireless networks as well as mobile
  communications of all kinds and also radio
  broadcasting.

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INVENTION

• Many people were involved in the invention of
  radio in its current form.
• Experimental work on the connection
  between electricity and magnetism began around
  1820 with the work of Hans Christian and others.
• These investigations culminated in a theory
  ofelectromagnetism developed by James Clerk
  Maxwell, which predicted the existence
  of electromagnetic waves.
• Maxwell published A Treatise on Electricity and
  Magnetism in 1873, stimulating many people to
  experiment with wireless communication.
• The first systematic and unequivocal
  transmission of EM waves was performed
  by Heinrich Rudolf Hertz and described in papers
  published in 1887 and 1890. Hertz famously
  considered these results as being of little
  practical value.
• After Hertz's work many people were involved in
  further development of the electronic
  components and methods to improve the
  transmission and detection of electromagnetic
  waves.
• Around the turn of the 20th century Guglielmo
  Marconi, developed the first apparatus for long
  distance radio communication.

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• On 23 December 1900, Reginald A. Fessenden
  became the first person to send audio (wireless
  telephony) by means of electromagnetic waves,
  successfully transmitting over a distance of
  about 1.6 kilometers, and six years later
  on Christmas Eve 1906 he became the first person
  to make a public radio broadcast.
• By 1910 these various wireless systems had come
  to be referred to by the common name "radio".

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ETYMOLOGY

• The term "radio" is derived from the Latin
  word radius, meaning "spoke of a wheel, beam of
  light, ray".
•  It was first applied to communications in 1881
  when, at the suggestion of French
  scientist Ernest Mercadier , Alexander Graham
  Bell adopted "radiophone" (meaning "radiated
  sound") as an alternate name for
  his photophone optical transmission system.
• The first use of radio- in conjunction with
  electromagnetic radiation appears to have been by
  French physicist Édouard Branly, who in 1890
  developed a version of a coherer receiver he
  called a radio-conducteur.
• The use of "radio" as a standalone word dates
  back to at least December 30, 1904, when
  instructions issued by the British Post Office
  for transmitting telegrams specified that "The
  word 'Radio'... is sent in the Service
  Instructions".

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USES

• Radio has also been developed with the
  development of technology.
•  It is one of the best ways for commutation as
  well as entertains people. 
• People can now also get radio play.
• When we consider the uses of radio in early
  days, we can simply say that the early uses of
  radio were maritime, so as to send telegraphic
  messages through the use of Morse code between
  ships land. 
• One of the other uses of radio in earlier days
  was to pass orders communications between
  armies navies.
• The common uses of radio during earlier times
  were for communications and sending messages. 
• Commercial radio broadcasts includes news,
  music, dramas, comedies, variety shows and
  different other forms of entertainment.

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• Now, many of the people use radio for listening
  music to know what are the latest songs and music
  groups.
•  They can know about what the weather is for
  that day and other news thats happening around
  the world.
• Digital radio, both satellite and terrestrial,
  provides improved audio clarity and volume.
•  Long-range radio signals enable astronauts to
  communicate with the earth from the moon and
  carry information from space probes as
  they travel to distant planets (see space
  exploration). For navigation of ships and
  aircraft the radio range, radio compass (or
  direction finder), and radio time signals are
  widely used. 

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TYPES OF RADIO

• All American Five
• Audion receiver
• Batteryless radio
• Foxhole radio
• Survival radio

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• Radios that combine transmitters and receivers
  are now widely used for communications. Police
  and military forces and various businesses
  commonly use such radios to maintain contact with
  dispersed individuals or groups. Citizens band
  (CB) radios, two-way radios operating at
  frequencies near 27 megahertz, most typically
  used in vehicles for communication while
  traveling, became popular in the 1970s. Cellular
  telephones, despite the name, are another popular
  form of radio used for communication.
• In Radio, a prominent industry CEO has been
  tireless in his fight for FM Radio chips to be
  deployed on all smart phones to allow users the
  ability to connect to their stations, without
  having to use a data connection. 

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THANK YOU