Communication is the act of conveying meanings from one entity or group to another through the use of mutually understood signs and semiotic rules. The main steps inherent to all communication are: The formation of communicative motivation or reason. Message composition. Message encoding. Transmission of the encoded message as a sequence of signals using a specific channel or medium. Noise sources such as natural forces and in some cases human activity begin influencing the quality of signals propagating from the sender to one or more receivers. Reception of signals and reassembling of the encoded message from a sequence of received signals. Decoding of the reassembled encoded message. Interpretation and making sense of the presumed original message; the scientific study of communication can be divided into: Information theory which studies the quantification and communication of information in general. The channel of communication can be visual, auditory and haptic, electromagnetic, or biochemical.
Human communication is unique for its extensive use of abstract language. Development of civilization has been linked with progress in telecommunication. Nonverbal communication describes the processes of conveying a type of information in the form of non-linguistic representations. Examples of nonverbal communication include haptic communication, chronemic communication, body language, facial expressions, eye contact, how one dresses. Nonverbal communication relates to the intent of a message. Examples of intent are voluntary, intentional movements like shaking a hand or winking, as well as involuntary, such as sweating. Speech contains nonverbal elements known as paralanguage, e.g. rhythm, intonation and stress. It establishes trust. Written texts include nonverbal elements such as handwriting style, the spatial arrangement of words and the use of emoticons to convey emotion. Nonverbal communication demonstrates one of Paul Wazlawick's laws: you cannot not communicate. Once proximity has formed awareness, living creatures begin interpreting.
Some of the functions of nonverbal communication in humans are to complement and illustrate, to reinforce and emphasize, to replace and substitute, to control and regulate, to contradict the denovative message. Nonverbal cues are relied on to express communication and to interpret others' communication and can replace or substitute verbal messages. However, non-verbal communication is ambiguous; when verbal messages contradict non-verbal messages, observation of non-verbal behaviour is relied on to judge another's attitudes and feelings, rather than assuming the truth of the verbal message alone. There are several reasons as to why non-verbal communication plays a vital role in communication: "Non-verbal communication is omnipresent." They are included in every single communication act. To have total communication, all non-verbal channels such as the body, voice, touch, distance and other environmental forces must be engaged during face-to-face interaction. Written communication can have non-verbal attributes.
E-mails and web chats allow an individual's the option to change text font colours, stationary and capitalization in order to capture non-verbal cues into a verbal medium. "Non-verbal behaviours are multifunctional." Many different non-verbal channels are engaged at the same time in communication acts and allow the chance for simultaneous messages to be sent and received. "Non-verbal behaviours may form a universal language system." Smiling, pointing and glaring are non-verbal behaviours that are used and understood by people regardless of nationality. Such non-verbal signals allow the most basic form of communication when verbal communication is not effective due to language barriers. Verbal communication is the written conveyance of a message. Human language can be defined as a system of symbols and the grammars by which the symbols are manipulated; the word "language" refers to common properties of languages. Language learning occurs most intensively during human childhood. Most of the thousands of human languages use patterns of sound or gesture for symbols which enable communication with others around them.
Languages tend to share certain properties. There is no defined line between a dialect. Constructed languages such as Esperanto, programming languages, various mathematical formalism is not restricted to the properties shared by human languages; as mentioned, language can be characterized as symbolic. Charles Ogden and I. A Richards developed The Triangle of Meaning model to explain the symbol, the referent, the meaning; the properties of language are governed by rules. Language follows phonological rules, syntactic rules, semantic rules, pragmatic rules; the meanings that are attached to words can be otherwise known as denotative.
The Bell System was the system of companies, led by the Bell Telephone Company and by AT&T, which provided telephone services to much of the United States and Canada from 1877 to 1984, at various times as a monopoly. On December 31, 1983, the system was divided into independent companies by a U. S. Justice Department mandate; the general public in the United States used the colloquial term Ma Bell to refer to any aspect of this conglomerate, as it held a near-complete monopoly over telephone service in most areas of the country, is still used by many to refer to any telephone company. Ma Bell is used to refer to the various female voices in recordings for the Bell System: Mary Moore, Jane Barbe, Pat Fleet, the current voice of AT&T. In 1877, the American Bell Telephone Company, named after Alexander Graham Bell, opened the first telephone exchange in New Haven, Connecticut. Within a few years local exchange companies were established in every major city in the United States. Use of the Bell System name referred to those early telephone franchises and comprised all telephone companies owned by American Telephone & Telegraph, referred to internally as associated companies, regional holding companies, or Bell operating companies.
In 1899, American Telephone & Telegraph acquired the assets of its parent, the American Bell Telephone Company. American Bell had created AT&T to provide long-distance calls between New York and Chicago and beyond. AT&T became the parent of American Bell Telephone Company, thus the head of the Bell System, because regulatory and tax rules were leaner in New York than in Boston, where American Bell was headquartered; the Bell System and its moniker "Ma Bell" became a term that referred to all AT&T companies of which there were four major divisions: AT&T Long Lines, providing long lines to interconnect local exchanges and long-distance calling services Western Electric Company, Bell's equipment manufacturing arm Bell Labs, conducting research and development for AT&T Bell operating companies, providing local exchange telephone services. In 1913, the federal government challenged the Bell System's growing monopoly over the phone system under AT&T ownership in an anti-trust suit, leading to the Kingsbury Commitment.
Under the commitment, AT&T escaped break-up or nationalization in exchange for divesting itself of Western Union and allowing non-competing independent telephone companies to interconnect with its long-distance network. After 1934, the Federal Communication Commission assumed regulation of AT&T. Proliferation of telephone service allowed the company to become the largest corporation in the world until its dismantling by the United States Department of Justice in 1984, at which time the Bell System ceased to exist. Receiving a U. S. patent for the invention of the telephone on March 7, 1876, Alexander Graham Bell formed the Bell Telephone Company in 1877, which in 1885 became AT&T. When Bell's original patent expired 15 years in 1894, the telephone market opened to competition and 6,000 new telephone companies started while the Bell Telephone company took a significant financial downturn. On April 30, 1907, Theodore Newton Vail returned as President of AT&T. Vail believed in the superiority of one national telephone system and AT&T adopted the slogan One Policy, One System, Universal Service.
This became the company's philosophy for the next 70 years. Under Vail, AT&T began acquiring many of the smaller telephone companies including Western Union telegraph. Anxious to avoid action from government antitrust suits, AT&T entered in 1913 into an out-of-court agreement known as the Kingsbury Commitment with the federal government. Following a government antitrust suit in 1913, AT&T agreed to the Kingsbury Commitment in which AT&T would sell its $30 million in Western Union capital stock, allow competitors to interconnect with its system, not acquire other independent companies without permission from the Interstate Commerce Commission; the Bell trademark pictured here was used from 1921 through 1939 by both the AT&T corporation and the regional operating corporations to co-brand themselves under a single Bell System trademark. For each regional operating company, its name was placed where "name of associated company" appears in this template version of the trademark. Bell system telephones and related equipment were made by Western Electric, a wholly owned subsidiary of AT&T Co.
Member telephone companies paid a fixed fraction of their revenues as a license fee to Bell Labs. As a result of this vertical monopoly, the Bell System owned most telephone service in the United States by 1940, from local and long-distance service to the telephones; this allowed Bell to prohibit its customers from connecting equipment not made or sold by Bell to the system without paying fees. For example, if a customer desired a style of telephone not leased by the local Bell company, he or she had to purchase the instrument at cost, furnish it to the telephone company for rewiring, pay a service charge, a monthly lease fee for using it. In 1949, the United States Department of Justice alleged in an antitrust lawsuit that AT&T and the Bell System operating companies were using their near-monopoly in telecommunications to attempt to establish unfair advantage in related technologies; the outcome was a 1956 consent decree limiting AT&T to 85% of the United States' national telephone network and certain government contracts, from continuing to hold interests in Canada and the Caribbean.
The Bell System's Canadian operations included the Bell Canada regional operating company and the Northern Electric manufacturing subsidiary of the Bell System's Western Electric equipment manufacturer. Western Electric divested Northern Electric in 1956, but AT&T did n
A payphone is a coin-operated public telephone located in a telephone booth or in high-traffic outdoor areas, with pre-payment by inserting money or by billing a credit or debit card, or a telephone card. Prepaid calling cards facilitate establishing a call by first calling the provided toll-free telephone number, entering the card account number and PIN the desired connection telephone number. An equipment usage fee may be charged as additional units, minutes or tariff fee to the collect/third-party, credit, telephone or prepaid calling card when used at payphones. By agreement with the landlord, either the phone company pays rent for the location and keeps the revenue, or the landlord pays rent for the phone and shares the revenue. Payphones are found in public places to contribute to the notion of universal access to basic communication services. One thesis, written as early as 2003, recognised this as a digital divide problem. In the 20th century, payphones in some countries, such as Spain, used token coins, available for sale at a local retailer, to activate pay phones, instead of legal tender coins.
In some cases these have been upgraded to use magnetic cards or credit card readers. In the past, payphones were ubiquitous around the world, but their prevalence has decreased over the years due to the increasing availability of mobile phones, but cell phone service is not always available in emergencies. Most payphones in Canada are owned and operated by large telecom providers such as Bell and SaskTel. In the last 20 years customer-owned coin-operated telephones have appeared in the market, but their numbers are smaller due to emergence of mobile phones; the cost of most local payphone calls is 50 cents CAD, having increased from 25 cents since 2007. Pay phones in Alberta were 35 cents for a time, but in most jurisdictions the price doubled. Newer phones allow users to use calling cards and credit cards. For coin-paid long distance, COCOTs are less expensive for short calls than incumbent providers. Dialing 0 for operator and 911 calls are still free; the Toronto Transit Commission deploys payphones on all subway platforms as a safety precaution.
As of 2013, there were about 70,000 payphones across the country. In 2013, the CRTC issued a temporary moratorium on the removal of payphones in small communities. In September 2015, the CRTC remarked that "32 per cent of Canadians used a payphone at least once in the past year," and that they are used "as a last resort in times of inconvenience and emergency." The payphone model 23, introduced at Deutsche Bundespost Telekom in 1992, is an electronic software controlled payphone for analog connections. It is equipped with coin, integrated test program setting, it has a remote maintenance, the independent reports of a background system by means of an integrated modem error, operating states or departures to the all public pay telephones of Deutsche Telekom AG are turned on. The Payphone 23 consists of two basic units, the equipment part including all the necessary for the operation modules and the secured below the growing payphone cassettes with the coin box. In Italy public payphones have been maintained over the years by Telecom Italia.
The majority of payphones on the street and in buildings in Japan are installed and maintained by Nippon Telegraph and Telephone. In the Soviet period different types of payphones were produced. There were long-distance call payphones costing 15 kopeks, provided services of paid media such as listening to an anecdote, obtaining legal advice, or finding the address of the subscriber by phone number. After the collapse of the Soviet Union and the monetary reform of 1991, this form of payment became irrelevant; some payphones were altered to accept tokens, while others have been designed to use telephone cards. For example, in St Petersburg, payment for payphones can be made with metro tokens. In some regions, calls from public phones are free of charge. Telephones were a monopoly of the national government. Pay phones took a slug or ficha, a piece of metal with two troughs in it, making it hard to counterfeit. Payphones were found in bars and stores, never freestanding. Phones would accept some 5 fichas at a time, showing through a plastic window the number remaining, return unused ones to the customer.
An older and simpler system was to use a mechanical counter, which automatically counted units of time, called pasos, a "pass" in the sense of "passage of time". The counter was the marcador de pasos; the length of each paso varied depending on the cost of the call. At the conclusion of a call the number of pasos was multiplied by a fixed amount, which could vary by time of day, creating a sum total that the customer would pay to a human attendant; these survived in small hotels at least until the 1970s. Spain had an institution with no equivalent in the United States, the locutorio "place where one talks", they were a type of store, in the main square of a town or close to it, where one booked a phone call by going to a counter, filling out a paper slip, handing it to a human. Sometimes advance payment was required; the recipient of the slip would either directly or indirectly
The E-carrier is a member of the series of carrier systems developed for digital transmission of many simultaneous telephone calls by time-division multiplexing. The European Conference of Postal and Telecommunications Administrations standardized the E-carrier system, which revised and improved the earlier American T-carrier technology, this has now been adopted by the International Telecommunication Union Telecommunication Standardization Sector, it was adopted in all countries outside the US, Japan. E-carrier deployments have been replaced by Ethernet as telecommunication networks transitions towards all IP. An E1 link operates over two separate sets of wires unshielded twisted pair or using coaxial. A nominal 3 volt peak signal is encoded with pulses using a method avoiding long periods without polarity changes; the line data rate is 2.048 Mbit/s, split into 32 timeslots, each being allocated 8 bits in turn. Thus each timeslot sends and receives an 8-bit PCM sample encoded according to A-law algorithm, 8,000 times per second.
This is ideal for voice telephone calls where the voice is sampled at that data rate and reconstructed at the other end. The timeslots are numbered from 0 to 31; the E1 frame defines a cyclical set of 32 time slots of 8 bits. The time slot 0 is devoted to transmission time slot 16 for signaling; the main characteristics of the 2-Mbit/s frame are described in the following. One timeslot is reserved for framing purposes, alternately transmits a fixed pattern; this allows the receiver to match up each channel in turn. The standards allow for a full cyclic redundancy check to be performed across all bits transmitted in each frame, to detect if the circuit is losing bits, but this is not always used. An alarm signal may be transmitted using timeslot TS0; some bits are reserved for national use. One timeslot is reserved for signalling purposes, to control call setup and teardown according to one of several standard telecommunications protocols; this includes channel-associated signaling where a set of bits is used to replicate opening and closing the circuit, or using tone signalling, passed through on the voice circuits themselves.
More recent systems use common-channel signaling such Signalling System 7 where no particular timeslot is reserved for signalling purposes, the signalling protocol being transmitted on a chosen set of timeslots or on a different physical channel. In an E1 channel, communication consists of sending consecutive frames from the transmitter to the receiver; the receiver must receive an indication showing when the first interval of each frame begins, so that, since it knows to which channel the information in each time slot corresponds, it can demultiplex correctly. This way, the bytes received in each slot are assigned to the correct channel. A synchronization process is established, it is known as frame alignment. In order to implement the frame alignment system so that the receiver of the frame can tell where it begins, there is so called a frame alignment signal. In the 2 Mbit/s frame system, the FAS is a combination of seven fixed bits transmitted in the first time slot in the frame. For the alignment mechanism to be maintained, the FAS does not need to be transmitted in every frame.
Instead, this signal can be sent in alternate frames. In this case, TS0 is used as the synchronization slot; the TS0 of the rest of the frames is therefore available for other functions, such as the transmission of the alarms. In the TS0 of frames with FAS, the first bit is dedicated to carrying the cyclic redundancy checksum, it tells us whether there are one or more bit errors in a specific group of data received in the previous block of eight frames known as submultiframe. The aim of this system is to avoid loss of synchronization due to the coincidental appearance of the sequence "0011011" in a time slot other than the TS0 of a frame with FAS. To implement the CRC code in the transmission of 2 Mbit/s frames, a CRC-4 multiframe is built, made up of 16 frames; these are grouped in two blocks of eight frames called submultiframes, over which a CRC checksum or word of four bits is put in the positions Ci of the next submultiframe. At the receiving end, the CRC of each submultiframe is calculated locally and compared to the CRC value received in the next submultiframe.
If these do not coincide, one or more bit errors is determined to have been found in the block, an alarm is sent back to the transmitter, indicating that the block received at the far end contains errors. The receiving end has to know, the first bit of the CRC-4 word. For this reason, a CRC-4 multiframe alignment word is needed; the receiver has to be told where the multiframe begins. The CRC-4 multiframe alignment word is the set combination "0011011", introduced in the first bits of the frames that do not contain the FAS signal; the CRC-4 method is used to protect the communication against a wrong frame alignment word, to provide a certain degree of monitoring of the bit error rate, when this has low values. This method is not suitable for cases in which the BER is around 10−3. Another advantage in using the CRC
Cable television is a system of delivering television programming to consumers via radio frequency signals transmitted through coaxial cables, or in more recent systems, light pulses through fiber-optic cables. This contrasts with broadcast television, in which the television signal is transmitted over the air by radio waves and received by a television antenna attached to the television. FM radio programming, high-speed Internet, telephone services, similar non-television services may be provided through these cables. Analog television was standard in the 20th century, but since the 2000s, cable systems have been upgraded to digital cable operation. A "cable channel" is a television network available via cable television; when available through satellite television, including direct broadcast satellite providers such as DirecTV, Dish Network and Sky, as well as via IPTV providers such as Verizon FIOS and AT&T U-verse is referred to as a "satellite channel". Alternative terms include "non-broadcast channel" or "programming service", the latter being used in legal contexts.
Examples of cable/satellite channels/cable networks available in many countries are HBO, Cinemax, MTV, Cartoon Network, AXN, E!, FX, Discovery Channel, Canal+, Fox Sports, Disney Channel, Nickelodeon, CNN International, ESPN. The abbreviation CATV is used for cable television, it stood for Community Access Television or Community Antenna Television, from cable television's origins in 1948. In areas where over-the-air TV reception was limited by distance from transmitters or mountainous terrain, large "community antennas" were constructed, cable was run from them to individual homes; the origins of cable broadcasting for radio are older as radio programming was distributed by cable in some European cities as far back as 1924. To receive cable television at a given location, cable distribution lines must be available on the local utility poles or underground utility lines. Coaxial cable brings the signal to the customer's building through a service drop, an overhead or underground cable. If the subscriber's building does not have a cable service drop, the cable company will install one.
The standard cable used in the U. S. is RG-6, which has a 75 ohm impedance, connects with a type F connector. The cable company's portion of the wiring ends at a distribution box on the building exterior, built-in cable wiring in the walls distributes the signal to jacks in different rooms to which televisions are connected. Multiple cables to different rooms are split off the incoming cable with a small device called a splitter. There are two standards for cable television. All cable companies in the United States have switched to or are in the course of switching to digital cable television since it was first introduced in the late 1990s. Most cable companies require a set-top box or a slot on one's TV set for conditional access module cards to view their cable channels on newer televisions with digital cable QAM tuners, because most digital cable channels are now encrypted, or "scrambled", to reduce cable service theft. A cable from the jack in the wall is attached to the input of the box, an output cable from the box is attached to the television the RF-IN or composite input on older TVs.
Since the set-top box only decodes the single channel, being watched, each television in the house requires a separate box. Some unencrypted channels traditional over-the-air broadcast networks, can be displayed without a receiver box; the cable company will provide set top boxes based on the level of service a customer purchases, from basic set top boxes with a standard definition picture connected through the standard coaxial connection on the TV, to high-definition wireless DVR receivers connected via HDMI or component. Older analog television sets are "cable ready" and can receive the old analog cable without a set-top box. To receive digital cable channels on an analog television set unencrypted ones, requires a different type of box, a digital television adapter supplied by the cable company. A new distribution method that takes advantage of the low cost high quality DVB distribution to residential areas, uses TV gateways to convert the DVB-C, DVB-C2 stream to IP for distribution of TV over IP network in the home.
In the most common system, multiple television channels are distributed to subscriber residences through a coaxial cable, which comes from a trunkline supported on utility poles originating at the cable company's local distribution facility, called the "headend". Many channels can be transmitted through one coaxial cable by a technique called frequency division multiplexing. At the headend, each television channel is translated to a different frequency. By giving each channel a different frequency "slot" on the cable, the separate television signals do not interfere with each other. At an outdoor cable box on the subscriber's residence the company's service drop cable is connected to cables distributing the signal to different rooms in the building. At each television, the subscriber's television or a set-top box provided by the cable company translates the desired channel back to its original frequency, it is displayed onscreen. Due to widespread cable theft in earlier analog systems, the signals are encrypted on m
Hook flash or flash is a button on a telephone that simulates hanging up picking up again. This action can signal the telephone exchange to do something. A common use of a hook flash is to switch to another incoming call with the call waiting service. Another use is to indicate a request for voice conferencing, for example, a user may use a procedure like the following to initiate three-way calling: Pick up phone handset. Hear a dial tone Dial the first number and greet the first party Press the hook flash button Hear a stutter dial tone Dial the second number and greet the second party Press the hook flash button again; the second "flash" signals the Central Office Switch to link the two active conversations, so that all three parties are connected to the same logical telephone line. In contrast to PBX conferencing systems, the two calls are joined at the Central Office switch, rather than at the customer premises PBX. On payphones, this function is provided with a button labeled Follow-on call, used for requesting another dial tone after finishing a call.
This allows remaining credit to be used on another call as payphones don't return changes. With payphones that do not have this button, flashing the handset on and off-hook will perform the same action; the switchhook is the device that senses whether the receiver is in its cradle. The term "flash" originated from the cord circuit of the early telephone switchboard that telephone company operators used to connect calls; the calling party and called party each had an indicator light on the cord circuit. When the subscriber cycled the telephone on-hook/off-hook, the light would flash. Actors in old movies demonstrate this method, seeking the operator's attention; the user does a tap-tap-tap. When an operator comes on the line, the actor says, "Hello? Operator? We've been cut off." The operator attempts to reestablish the connection. The flashing light of this equipment of bygone days is the origin of the phrase "flashing the switchhook". Centrex telephones added a hook-flash button in the 1960s, after some users incorrectly attempted the attendant-recall function