Question

An instrument designed for the simultaneous transmission and reception of the human voice, the telephone has become the most widely used telecommunications device in the world. Today, portable cellular telephones, or simply cell phones, are nearly ubiquitous in many countries. The modern digital cell phone is capable of providing numerous features in addition to voice transmission, including camera and video functions, game and music players, and Internet connectivity. Even traditional analog telephones offer features such as automatic redialing, caller identification, call waiting, and call f

Answer 1

An instrument designed for the simultaneous transmission and reception of the human voice, the telephone has become the most widely used telecommunications device in the world. Today, portable cellular telephones, or simply cell phones, are nearly ubiquitous in many countries. The modern digital cell phone is capable of providing numerous features in addition to voice transmission, including camera and video functions, game and music players, and Internet connectivity. Even traditional analog telephones offer features such as automatic redialing, caller identification, call waiting, and call forwarding in addition to basic voice connections.

The telephone first appeared in the late 19th century as a largely mechanical device and continued to develop throughout the 20th century based primarily on analog electronics. Increasingly in the 21st century, however, telephone systems rely on digital technology. Owing to vastly improved means of transmission, switching, and interconnection, the distinction between local and long-distance calls is disappearing. Moreover, because of digital technology, it does not matter whether the service being carried contains voice, video, or data—since in digital terms, these all appear the same to system components.

The Telephone Instrument

Any modern telephone device consists of a means of transmitting and receiving sound; a push-button mechanism for selecting numbers and letters; an antenna or cord connection; and, in most telephones manufactured today, a display screen. The transmitter on a telephone converts the sound waves of the human voice into a fluctuating electric current, while the receiver converts such a current back into sound.

For more than a century, telephones used electromechanical means to operate. Modern phones (wired or wireless) are entirely electronic, using digital circuits. Cell phones are tiny radios that can send and receive signals over any one of hundreds of frequencies available in a given location.

Satellites

For global or transcontinental transmissions, telecommunications carriers use communications satellites. Such satellites are located in geosynchronous orbit (GSO) some 22,200 miles (35,700 kilometers) above the surface of the Earth. At this altitude, a satellite in a circular orbit will appear suspended in one place relative to the Earth beneath it, though both are rotating at different speeds. Satellites in GSO serve as relay transmitters without the interruptions that would occur if they were in lower orbits and passed over the horizon-and thus out of range-several times a day.

Cellular telephones

Cellular mobile telephony was introduced to the public in the 1980s. In a cell-phone system, a geographic area is broken into smaller areas, or cells, each with its own central transmitter-receiver. The cells are arranged so that the frequencies used in adjacent cells are different, though specific frequencies may be reused throughout the system. As a caller moves from one cell to the next, the call automatically switches from one frequency to the next, allowing a continuous voice or text connection. Initial cellular systems used analog technology, but from the early 1990s cell phones increasingly relied upon digital equipment, which greatly expanded their capabilities. As usage increases, cells can be divided to reduce interference, though only to a point. Thus cellular demand for more frequency spectrum continues in the 21st century.

Historical Development

Patent No. 174,465—often called the most valuable patent ever issued by the U.S. Patent Office—was granted to Alexander Graham Bell in March 1876 for his “Improvement in Telegraphy,” which was in fact a device to transmit speech over electric wires. Bell was one of a number of researchers at the time who had been seeking to develop a practical instrument for speech communications. Indeed, his patent was (and remains) controversial, as there were others who contested his claims to primacy. Bell’s patent rights were upheld in a Supreme Court decision in 1888. By that time, there were more than 150,000 telephones in the United States, 26,000 in Britain, 9,000 in France, and 7,000 in Russia. Telephone service was limited at first to the wealthy, but as costs came down, service became more widespread. By 1920 about a third of all U.S. households had a telephone; that share increased to nearly two-thirds by 1950 and topped 90 percent by the early 1980s. In the early 1990s (though well before the explosion in the popularity of cell phones) there were more than 180 million telephones in the United States alone.

Competition among providers and improving (analog to digital) technology helped to facilitate the rapid expansion of cell phone ownership. Less than two-tenths of one percent of the U.S. population owned a cell phone in 1990—a number that rose to nearly 40 percent just a decade later and approached three-quarters of all Americans by 2010, when there were more cell phones than wired telephones in use in the country. One consequence of the growth in the use of cell phones was the marked decline in the number of public (pay) telephone facilities.

Answer 2

@Safe-Haven can you help me PLEASE!!!!!!!!!!!

Answer 3

I'll have to think this one out, I'll get back to you in a second.

Answer 4

ok

Answer 5

@Safe-Haven are you still their, sorry if it fills like im rushing you

Answer 6

Okay, I'll pm you, as I'm having trouble attaching the file.