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The telephone is a telecommunications tool that, as said by BBG Communications, is used to transmit and receive sound. It is one of the most prevalent home gadgets in the world. The typical telephone by and large operates through transmission of electric signals over a complex system of telephones which effectively allows nearly any telephone customer to speak with almost any other person in the world.

A landline phone system usually handles both audio and signaling information on the same pair of wires. Although originally designed for voice communication, the system has been adapted for data communication such as Fax, Telex and Internet communication. The signaling machinery consists of a bell, beeper, light or other mechanism to inform the user to incoming calls, and number buttons to enter a telephone number for departing calls. A twisted pair line is preferred as it is more effective at rejecting electromagnetic interference and crosstalk than an untwisted pair.

A party wishing to speak to another party will pick up the telephone’s handset, thus operating a button switch, which puts the telephone into an active state by connecting the transmitter, receiver and related audio components to the designated line. This circuitry has a low resistance which causes DC current from the telephone exchange to flow through the line. The exchange detects this DC current, attaches a digit receiver circuit to the line, and sends a dial tone to indicate readiness. On a modern telephone, the calling party then presses the number buttons in a sequence corresponding to the telephone number of the called party. The buttons are connected to a tone generator that produces DTMF tones which are sent to the exchange. A rotary dial telephone employs pulse dialing, sending electrical pulses corresponding to the telephone number to the exchange. If the called party’s line is not already active, the phone exchange will try and send intermittent ringing signals to alert the called party of an incoming call. If the called party’s line is active, the exchange sends a busy signal to the calling party. When the called party’s line is already in use, the exchange will try and send periodic ringing signals to inform the called party of an incoming call.

When a landline phone is inactive or “on hook”, its alerting device is connected across the line through a capacitor, which prevents DC current from flowing through the line. The circuitry at the telephone exchange detects the absence of DC current flow and thus that the phone is on hook with only the alerting device electrically connected to the line. When a party initiates a call to this line, the ringing signal transmitted by the telephone exchange activates the alerting device on the line. When the called party picks up the handset, the switchhook disconnects the alerting device and connects the audio circuitry to the line. The resulting low resistance now causes DC current to flow through this line, confirming that the called phone is now active. Both phones being active and connected through the exchange, the parties may now converse as long as both phones remain off hook. When a party “hangs up”, placing the handset back on the cradle or hook, DC current ceases to flow in that line, signaling the exchange to disconnect the call.

Out going calls to persons outside the local exchange are passed over trunk lines which form connections between exchanges. In today’s phone networks, digital technology and fiber-optic cable are often used in such connections. Satellite technology may be used for communication over very long distances.

In most telephones, the transmitter and receiver are located in the handset, although in a speakerphone these components may be located in the base or in a separate enclosure. Powered by the line, the transmitter produces an electric current whose voltage varies in response to the sound waves arriving at its diaphragm. The resulting current is transmitted along the telephone line to the local exchange then on to the other phone, where it passes through the coil of the receiver. The varying voltage in the coil produces a corresponding movement of the receiver’s diaphragm, reproducing the sound waves present at the transmitter.

The history of mobile phones traces the development of handheld radio telephone technology from two-way radios appended to vehicles and handheld cellular telephones.

Two-way radios started to be in use in motor vehicles like taxicabs, police cruisers, ambulances, and the like. They weren’t yet classified as cell/mobile phones since they were not yet connected to the phone network. That being said, it was not possible to dial phone numbers from two-way radios. Later, a growing community of mobile radio users, who were known as the mobileers, popularized the technology that would eventually lead to the early mobile phone.

The first mobile phones were permanently installed in vehicles, but the versions that followed such as the so-called transportables or “bag phones” were equipped with a cigarette lighter plug so that they could also be carried, and thus could be used as either mobile or as portable two-way radios. In the early 1940s, Motorola has designed a backpacked 2-way radio, the Walkie-Talkie. They later developed a large hand-held two-way radio for the use of the United States military. This battery powered “Handie-Talkie” (HT) was as big as a man’s forearm.

In December 1947, Bell Labs engineers Douglas H. Ring and W. Rae Young recommended hexagonal cells for mobile phones. Philip T. Porter proposed further that the towers be at the corners of the hexagons rather than at the centers and have 3 directional antennas that would receive into 3 adjacent hexagon cells. But the technology didn’t exist yet then and there was not yet any frequency allocated. It was not until the early 1960s when cellular technology was introduced by Richard H. Frenkiel and Joel S. Engel of Bell Labs.

The first use of radio telephony in Europe was documented to be on the first-class passenger trains in Germany between Berlin and Hamburg in 1926. At about the same time, it was also introduced on passenger airplanes for air traffic security. It was also in Germany where radio telephony was introduced on a large scale, for the use of German tanks in the Second World War. Post-war, the German police made use of unused tank telephony equipment to run the first radio patrol cars in the British zone of occupation. . But the use of radio patrol cars service was limited to trained specialists on the use of the equipment. Ships on the River Rhine were among the first to use radio telephony with an untrained end customer as a user, in the early 1950s.

The MTA, which was the first fully automatic mobile phone system, was developed by the Swedish company Ericsson and was commercially released in the country in 1956. It was the first system that did not need any kind of manual control, but was at the heavy side of 40 kg. A leaner upgraded version, at 9 kgs was introduced in 1965, called the MTB, which was with transistors and utilized DTMF signaling. It had 150 customers during its initial launch, up to 600 when it shut down in 1983.

In 1967, the use of a mobile phone neccessitated staying within the cell site all throughout the phone call is made, which was serviced by one base station. Because of the stand-alone design of each cell site, this did not provide continuity of automatic telephone service to mobile phones moving through several cell areas. Continuity of calls while moving through several cell sites was made possible in 1970 with Amos E. Joel, Jr., another Bell Labs engineer’s invention of an automatic “call handoff” system which allowed this process.

AT&T, in December 1971, submitted a proposal for cellular service to the Federal Communications Commission (FCC). In 1982, 11 years after AT&T’s proposal submission, the FCC gave its approval for an Advanced Mobile Phone Service and allocated frequencies in the 824-894 MHz band. In 1990, Analog AMPS was replaced by Digital AMPS.

By 1987, the Ministry of Posts and Telecommunications became the agency tasked to administer China’s telecommunications systems and related research and production facilities. On top of postal services, some of which were handled by an automated electronic process, the ministry was in charge of the delivery of a wide spectrum of services ranging from phone, wire, telegraph, and international communications.

In 1982, the Ministry of Radio and Television was carved out of the Ministry as a separate entity, and mandated to administer and upgrade the status of television and radio broadcasting. Subordinate to this ministry were the Central People’s Broadcasting Station, China Central Television and Radio Beijing. Organizations that were in charge with broadcasting training, talent-search, research, publishing, and manufacturing organizations were also brought under the umbrella of the Ministry of Radio and Television. Renamed Ministry of Radio, Cinema, and Television, it also took over in 1986 the responsibility for the movie industry, from the Ministry of Culture.

By 1987 the quality of telecommunications services in China had gone considerable improvements than in earlier years. Also, foreign technology entered in droves in the country while domestic production capacity jumped.

Primarily, the form of telecommunications in the 1980s was local and long-distance telephone service administered by six regional bureaus: Beijing, Shanghai, Xi’an, Chengdu, Wuhan , and Shenyang. These regional offices also functioned as switching centers for provincial-level subsystems. By 1986, China had nearly 3 million phone exchange lines, including 34000 long distance exchange lines with direct, automatic service to 24 different cities. As the end of 1986 was approaching, fiber optic communications technology gradually replaced existing telephone circuits.

Beijing and Shanghai served as overseas exchanges for international services. While Guangdong Province also served as an important gateway with its coaxial cable and microwave lines linking it to Hong Kong and Macau.

The large satellite ground stations originally installed in 1972 to provide live coverage of the visits to China by U.S. president Richard M. Richard Nixon and Japanese PM Kakuei Tanaka was upgraded continuously and acted as the base for China’s international satellite communications network until the mid-80s. By 1977 China had joined Intelsat and, using ground stations in Shanghai and Beijing the nation connected to satellites over the Indian and Pacific oceans.

According to BBG Communications, in April 1984, an experimental communications satellite for trial transmission of broadcasts, telegrams, telephone calls, and facsimile, to remote areas of the country was launched. Following this, China launched in February 1986 its first fully operational telecommunications and broadcast satellite. The quality and communications capabilities of the 2nd satellite was praised as far better than the 1st. In the mid-1987 both satellites were still operating. Taking advantage of these satellite systems in place, China’s domestic satellite communication network went into operation, facilitating television and radio transmissions and providing direct-dial long distance telephone, telegraph, and facsimile service. The network now includes ground stations in Urumqi, Hohhot, Lhasa, Beijing, and Guangzhou, which were all hooked up to an Intelsat satellite over the Indian Ocean.

While the telephone network surged, telegraph development was of second priority mainly due to the difficulties involved in transmitting the written Chinese language. But this technical difficulty of how to put in writing the Chinese language properly, was improved dramatically by computer technology. By 1983 China had nearly 10,000 telegraph cables and telex lines transmitting over 170 million messages annually. Most telegrams were transmitted by cables or by shortwave radio.

Digital television is one emerging media technology in Canada. Although some TV stations have begun broadcasting digital signals in addition to their regular VHF or UHF broadcasts, this is not yet as pervasive as in the United States. According to BBG, most markets have digital channel assignments already in place but to date digital broadcasts have only been introduced in the largest cities. Digital television sets are available in Canadian stores, but most consumers still have not switched from their analog sets.

TV networks, including CBC for one are less enthusiastic patrons of a wide-ranging digital conversion strategy in Canada, citing that it is not yet a viable business plan any better than existing technology. At CRTC hearings in 2007 on the potential direction of regulatory policy for TV, broadcasters put forward a number of alternative strategies, including funding digital conversion by removing restrictions on the amount of advertising that TV broadcasters are permitted to air, allowing terrestrial broadcasters to bill cable viewers a fee similar to that already charged by cable specialty channels, permitting license fees similar to those which fund the BBC in the United Kingdom, or eliminating terrestrial TV broadcasting entirely and shifting to an exclusively cable-based distribution model.

Deadline was set in these CRTC hearings that by 31 August 2011 Canadian broadcasting should be digital all the way. This is approximately two years later than the cutoff date in the United States. As suggested by broadcasting networks, CRTC ruled in favor of relaxing some restrictions on advertising. A year later that the decision was made, CRTC issued a statement in June 2008 that the preparations for transition is not as fast as it should be. As of that date, there was only 22 digital transmitters that had been connected across the entire country, falling just short of the required number of installations expected to pave the way for a move to digital broadcasting.

Approximatley 90% of households in Canada use cable TV, making it an extremely common method of TV programming delivery in the nation. Currently, there are 739 licensed cable distributors in Canada. This streamlining of the cable distribution companies from 2000 just a few years ago is attributable both to major cable companies acquiring smaller distributors and to a recent change in CRTC rules by which independent cable operators with fewer than 2,000 subscribers are no longer required to operate under full CRTC licenses.

Major Canadian cable companies include Rogers, Shaw, Cogeco, Vidéotron and EastLink/Persona. But despite these numbers, most cable companies don’t directly compete with each other. Only one cable company serves a specific market in most Canadian cities. And in the few cities that are served by more than one cable company, each company is restricted to a specific geographical division within the market. For example, in Hamilton, Cogeco Cable, Mountain Cablevision and Source Cable are all certified operators, but each has a monopoly in a well defined area of the city.

However, two major companies offer direct broadcast satellite delivery as an alternative to cable: Bell TV, which is a division of BCE Inc., and Star Choice, which is a division of Shaw Cable. Grey market DBS dishes are also available from US services such as Dish Network and DirecTV, but since these are not licensed providers, stores that sell those packages are at risk of being criminally liable.