How did Radio and wireless communication reach to us - Technopediasite

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Sunday, March 11, 2018

How did Radio and wireless communication reach to us

Introduction about How did Radio and wireless communication reach to us
Short explanation about the pioneers of wireless communications. I will try to explain the
discovery & the inventor & the experiments. There were hundreds of contributors to the
evolution of wireless communications, I would like to share about the major contributions
 to wireless communications.
Here we will know the development of wireless voice, data, and video services.

Georg Simon Ohm
Georg Simon Ohm, in 1826, produced a mathematical description of conduction in circuits
 & it was the heat conduction. In 1827, Ohm detailed his complete theory of electricity.
Ohm’s law states-
I = V/R
Joseph Henry
Joseph Henry was the first director of the Smithsonian Institution (1846), and one of the
founding members of the National Academy of Sciences. Henry independently discovered electromagnetic self-induction in 1831, but the credit for being first is given to Michael Faraday. Further Henry demonstrated the potential of a William Sturgeon invented device for long-distance Communications by sending an electronic current more than 1.6 km of cable to activate an electromagnet that caused a bell to strike. Thus the electric telegraph was born.
Michael Faraday
Michael Faraday known for his discoveries of electromagnetic induction and the laws of
electrolysis. Faraday built two devices to produce what he called electromagnetic rotation: that is a continuous circular motion from the circular magnetic force around a cable. In 1831
 he discovered electromagnetic induction. These type of experiments form the basis of modern and latest electromagnetic technology. Scientist Faraday was discovered magnetoelectric induction: it was the production of a steady electric current.

James Clerk Maxwell
Maxwell’s discovery of the ether (or metaphor) led to many advances in electronic communications. Maxwell extension of the electromagnetic theory of light led directly to the Heinrich Hertz’s discovery of radio waves and to the related advances in science and technology of today. Maxwell’s mathematical equations was explaining the behavior of electric and magnetic fields and their interrelated nature—were valid, even though his theory of the ether was not. Maxwell’s calculations were scientific observations resulting in his conclusion that the speed of propagation of an electromagnetic field is approximately that of the speed of light (300 million m/sec). Maxwell concluded that ultimate visible light forms only a small part of the entire spectrum of possible electromagnetic radiation (EMR).

Heinrich Hertz
Scientist Heinrich Hertz applied Maxwell’s theories to the production and reception of radio waves for the communication. In recognition of Hertz's work, the unit of frequency of a radio wave—one cycle per second —is named the hertz.

In the year 1888, Scientist Hertz generated electric waves by means of the oscillatory discharge of a condenser through a loop provided with a spark gap and then detecting them with a similar type of circuit. Hertz’s condenser consisted of a pair of metal rods, placed end to end with a small gap for a spark to generate between them. When these rods were given charges of opposite signs, strong enough to spark, the current would oscillate back and forth across the gap and along the rods. With this oscillator, Hertz solved two problems:
• Timing Maxwell’s waves—Scientist Hertz had demonstrated, in the concrete, what Maxwell had only theorized: that the velocity of radio waves was equal to the velocity of light
• How to make the electric and magnetic fields detach themselves from wires and go as free
as Maxwell’s waves
Guglielmo Marconi
first wireless
first wireless

Guglielmo Marconi who sent the first wireless message more than 100 years ago.
By 1895, Guglielmo Marconi had developed an apparatus or device with which he succeeded in sending signals to a point a few kilometers far away by means of a directional antenna. In 1897, he used his radio apparatus to create the first radio transmitter, thus it was the birth of radio.Marconi was awarded a patent for his wireless telegraph system for tuned communication. Marconi successfully transmitted the first wireless telegraph signal via radio across the Atlantic Ocean from Cornwall to Newfoundland.

Overview of Wireless Development for Voice, Video, and Data Wireless Voice 
Voice Over Radio:-
Voice over radio was first introduced in 1914 by the Marconi Corporation. With the
introduction of the vacuum tube in radio technology, systems were capable of transmitting
voice signals as well as telegraph signals. The first music over radio was broadcast from a
ship off of the coast of San Diego in February 1917.

It was the success year in January 1927, commercial long-distance radio telephone service was introduced between the United States and Great Britain. The American Telephone and Telegraph Company (AT&T) and the British Postal Office jointly aired the service after four years of experimenting.

They expanded the service later to communicate with Canada, Australia, South Africa,
Egypt, and Kenya, as well as with ships at sea. This service eventually had 14 dedicated
channels, or frequencies, assigned to it. The overseas transmitter was at Rugby, England, and the U.S. transmitter was at Deal, New Jersey.

Mobile Telephony
On June 17, 1946, in Saint Louis, AT&T and Southwestern Bell introduced the first American commercial mobile radiotelephone service. Mobiles used newly issued vehicle radiotelephone licenses granted to Southwestern Bell by the Federal Communications Commission (FCC).
cell site for wireless communication
cell site
They operated on six channels in the 150 MHz band with 60 kHz channel spacing.
In 1947, AT&T began a radiotelephone operation that provided service between New York
and Boston.

In 1948, first day of the month March, the first fully automatic radiotelephone service began operating in Richmond, Indiana, eliminating the operators who placed most calls. In 1964, the Bell System introduced improved mobile telephone service (IMTS), a replacement to the badly aging mobile telephone system (MTS). It worked in full duplex, eliminating the need of having to press a button to talk. MTS finally permitted direct dialing, automatic channel selection, and reduced bandwidth to 25 to 30 kHz.

Cellular
Cellular telephone technologies, while initially used only for voice, have developed into an
alternate form of data communications. Cellular telephone systems consist of a grid of
transceivers that operate in a limited space, known as a cell. Cells must be overlapped to
insure coverage as users travel from cell to cell. The process of transferring communications from cell to cell is referred to as a hand off. As the cells hand off the communications channel, the hardware (cellular telephone) must assume the frequency of the new cell controlling the connection.

Because of the demand for cellular service and limited bandwidth made available for these
services, several multiplexing techniques were developed to maximize usage of available
resources:
• Frequency division multiple access (FDMA)
• Time division multiple access (TDMA)
• Code division multiple access (CDMA)
• Global System for Mobile Communications (GSM)
Other than private military systems, most hardware for cellular systems is owned and
maintained by the many private carriers operating worldwide. The end user need only
purchase the least expensive piece of hardware, the cellular telephone, personal digital
assistant (PDA), or other wireless device. As demand increases, cost continues to decrease for these devices, while they both shrink in size but grow in capabilities.

The basic concept of cellular telephones began in 1947 when researchers looked at crude
mobile (car) telephones and realized that by using small cells (range of service area) with
frequency reuse they could increase the traffic capacity of mobile telephones substantially.
However, the technology for implementation of their ideas was unavailable at the time.
In 1947, the FCC classified cellular telephones as a two-way radio device and set limits on the frequencies allocated for its use. Because of the limited frequencies allotted by the FCC, only 23 cellular telephone conversations could occur simultaneously in the same service area, limiting use and development.

In 1968, the FCC allocated additional frequencies for cellular telephone service, leading to
more companies researching and developing the technology.

By 1977, AT&T Bell Labs constructed and operated a prototype cellular telephone system.
A year later, public trials of the new system began in Chicago, IL, with more than 2000 trial
cellular telephone customers. In the year 1979, the first commercial cellular telephone system began operation in Tokyo, and in 1981 Motorola and American Radio Phone started a second U.S. cellular radiotelephone system test in the Washington/Baltimore area.

By 1982, the FCC authorized commercial cellular telephone service in the United States.
A year later, Ameritech offered the first American commercial analog service, or advanced
mobile phone service (AMPS), in Chicago. Despite the incredible demand, it took 37 years
for cellular telephone service to become widely available in the U.S. These networks have
now evolved into digital networks using protocols such as TDMA, CDMA, and GSM.

Personal Communications System (PCS)
PCS evolved from mobile satellite technology.
In 1965, when Early Bird was launched, the satellite provided almost 10 times the capacity of the submarine telephone cables for almost one tenth the price.

In February 1976, Communications Satellite (COMSAT) Corporation launched a new kind of
satellite, Maritime Communications Satellite (MARISAT) System, to provide mobile services
to the U.S. Navy and other maritime customers. In the early 1980s, the Europeans launched
the Maritime European Communications Satellite (MARECS) series to provide the same services.

PCS was introduced in 1998. In the fully developed PCS, a person can carry a wireless
telephone anywhere to be used for voice or data. Several companies have committed
themselves to providing a version of this system using satellites in low earth orbit (LEO).
Modern day PCS is the result of the FCC’s auctioning of frequencies in 1995. It is a new
generation of wireless telephone technology that introduces a range of features and services surpassing those available in analog and digital systems. Operating at 1.8 GHz for mobile telephony, PCS today provides the user with an all-in-one wireless telephone complete with paging, messaging, and data services with a greatly improved battery standby time. When the 900 MHz GSM cellular network was developed, provisions were made for a second network in the 1.8 GHz range. The higher frequency was expected to be used for low-cost, highly portable PCS. In the United States, the FCC saw an opportunity to:

• Increase the spectrum for mobile telephony.
• Increase competition for the two cellular providers.
• Adopt a worldwide frequency standard for mobile telephones.
The original cellular networks were developed for car telephones, and the progression to
portables made a worldwide frequency standard desirable.
The original cellular licenses were awarded in a lottery by using metropolitan statistical area
(MSA) and rural service area (RSA), which were developed by Rand McNally for map census areas. For PCS, the FCC auctioned the frequencies in six blocks designated A to F. The PCS licenses were awarded using slightly different census areas (also from Rand McNally) called metropolitan trading area (MTA) and basic trading area (BTA). A major difference in the two schemes is that MTAs overlap BTAs like cities are to states or provinces (the New York BTA is part of the New York MTA). PCS networks use similar technology to cellular, with radio base stations connected to a mobile switching center (MSC). Three different digital protocols have been deployed:
• CDMA
• TDMA
• GSM
The protocols are similar to cellular but are used at a different frequency. Many carriers also
offer dual mode, dual frequency mobiles that work on both the cellular and PCS network.
Because all of these networks connect to the public switched telephone network (PSTN), a
CDMA PCS telephone can be used to talk to a TDMA cellular telephone. The PSTN acts as a protocol converter.

Wireless Video/Television
Television was not invented by a single person—many people working together and alone
contributed to the evolution of television. Some events involving broadcast and satellite
television are described in this section.

Broadcast Television
The following time line summarizes the development of broadcast television:
• In year 1862—Abbe Giovanna Caselli invented his pantelegraph and became the first person to transmit a still image over wires.
• 1884—Paul Nipkow sent images over wires using a rotating metal disk technology, called
an electric telescope, with 18 lines of resolution.
• 1926—John Baird operated a system with 30 lines of resolution at five frames per second.
• 1927—Bell Telephone and the U.S. Department of Commerce conducted the first long distance use of television between Washington, D.C., and New York City. Secretary of
Commerce Scientist Herbert Hoover commented, “Today we have, in a sense, the transmission of sight for the first time in the world’s history for the communication. Really human genius has now destroyed the impediment of distance factor in a new respect, and in a manner hitherto unknown.” Shortly thereafter, Philo Farnsworth filed for a patent on the first complete electronic television system for the public, which he called an image dissector.

• 1928—The Federal Radio Commission issued the first television license (W3XK) to
Charles Jenkins.
• 1933—Iowa State University (W9XK) began broadcasting twice weekly television
programs in cooperation with radio station WSUI.
• 1937—Stanford researchers, brothers Russell and Sigurd Varian, introduced the klystron,
a high-frequency amplifier for generating microwaves. The klystron is considered the
defining technology that makes ultrahigh frequency (UHF) television possible because it
provide the ability to generate the high power required in this spectrum.
• 1940—Peter Goldmark invented color television with 343 lines of resolution.
• 1946—Working for CBS, Goldmark demonstrated his color television system to the FCC.

His system produced color pictures with the use of a red-blue-green wheel spinning in
front of a cathode ray tube. Although Goldmark’s mechanical system was eventually
color television system. The National Television System Committee (NTSC) is responsible for setting television and video standards in the United States. The NTSC standard is the super dominant television standard in the United State.On the other hand Phase alternating line (PAL) is the dominant television standard in Europe.

Système électronique couleur avec mémoire (SECAM) is the dominant television standard in France, Russia, Northern Africa, and the Middle East. Whereas NTSC delivers 525 lines of resolution at 60 half-frames per second, PAL delivers 625 lines at 50 half-frames per second, and SECAM delivers 625 lines at 25 frames per second.

Satellite Television
The following events describe satellite television broadcasting:
• 1962—AT&T launched Telstar, the first satellite to carry television broadcasts.
Broadcasts were now internationally relayed.
• 1978—The Public Broadcasting Service became the first station to switch to all satellite
delivery of programs.
• 1983—Direct broadcast satellite began service in Indianapolis.

Wireless Data Radio and Telegraph
The first uses of wireless communications are outlined below:
• 1896—Marconi obtained a patent and established the Wireless Telegraph and Signal
Company Limited for the same,It was the first radio factory in the world.
• 1901—Signals were received across the Atlantic.
• 1905—In this year the first wireless distress signal was sent using Morse code.

After the invention of wireless communication,the Wireless technology eventually progressed as an invaluable tool used by the U.S. military. The military configured wireless signals to transmit data over a medium using complex encryption, making unauthorized access to network traffic almost impossible. Even wireless technology was first introduced during World War II when the Army began sending battle plans over enemy lines and when the Navy instructed its fleet.

Wireless Data Networks
As opposed to mobile voice services, mobile data networks have been slow in hitting the
marketplace and have not proliferated. The hope is that PCS will fill that gap between
wireless voice and data.

The first wireless data networks came together in 1970 when networking technologies met
radio communications at the University of Hawaii as a research project called ALOHAnet.
Without using telephone lines, the bidirectional star topology of the system included seven
computers deployed over four islands to communicate with the central computer on Oahu.
From the invention of the ALOHAnet, wireless data networks developed throughout the
world. The following text summarizes some of the time lines where other countries were
connecting to the Internet or developing wireless network technologies:

• 1977—In this year the first demonstration occurred of Advanced Research Projects Agency Network that called the (ARPAnet)/SF Bay Packet Radio Net/Atlantic SATNET operation of Internet protocols.

• 1979—In this year devoted radio group in Vancouver developed the first hardware equipment that dedicated to packet radio communications, called terminal node controllers (TNCs). The development of radio hardware and specialized protocols accelerated after May 1980 when the FCC authorized amateur packet radio operations at 220 MHz for ASCII transmissions (text files). By the end of 1983, approximately 659 TNCs were operating in the North America, actually many running a variant of the X.25 packet switched protocol called AX.25.

• 1982—Norway left the network to become an Internet connection via transmission
control protocol/Internet protocol over SATNET.
• 1987—E-mail link established between Germany and China using Computer Science
Network protocols, with the first message from China sent on September 20.
• 1985—Neda Rayaneh Institute, Iran’s first commercial provider, came online, connecting
via satellite to Cad-vision, a Canadian provider.
• 1999—Internet access became available to Saudi Arabia using Juniper M40 routers.

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