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Transparency (telecommunication)
In telecommunications, ''transparency'' can refer to: #The property of an entity that allows another entity to pass through it without altering either of the entities. #The property that allows a transmission system or channel to accept, at its input, unmodified user information, and deliver corresponding user information at its output, unchanged in form or information content. The user information may be changed internally within the transmission system, but it is restored to its original form prior to the output without the involvement of the user. #The quality of a data communications system or device that uses a bit-oriented link protocol that does not depend on the bit sequence structure used by the data source. Some communication systems are not transparent. Non-transparent communication systems have one or both of the following problems: * user data may be incorrectly interpreted as internal commands. For example, modems with a Time Independent Escape Sequence or 20th centu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telecommunication
Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than that feasible with the human voice, but with a similar scale of expediency; thus, slow systems (such as postal mail) are excluded from the field. The transmission media in telecommunication have evolved through numerous stages of technology, from beacons and other visual signals (such as smoke signals, semaphore telegraphs, signal flags, and optical heliographs), to electrical cable and electromagnetic radiation, including light. Such transmission paths are often divided into communication channels, which afford the advantages of multiplexing multiple concurrent communication sessions. ''Telecommunication'' is often used in its plural form. Other examples of pre-modern long-distance communication included audio messages, such as coded drumb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blue Box (phreaking)
A blue box is an electronic device that produces tones used to generate the in-band signaling tones formerly used within the North American long-distance telephone network to send line status and called number information over voice circuits. This allowed the user, referred to as a "phreaker", to surreptitiously place long-distance calls that would be billed to another number or dismissed entirely as an incomplete call. A number of similar "color boxes" were also created to control other aspects of the phone network. First developed in the 1960s and used by a small phreaker community, the introduction of low-cost microelectronics in the early 1970s greatly simplified these devices to the point where they could be constructed by anyone reasonably competent with a soldering iron or breadboard construction. Soon after, models of relatively low quality were being offered fully assembled, but these generally required tinkering on the part of the user to keep operational. An exceptio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
In-band Signaling
In telecommunications, in-band signaling is the sending of control information within the same band or channel used for data such as voice or video. This is in contrast to out-of-band signaling which is sent over a different channel, or even over a separate network. In-band signals may often be heard by telephony participants, while out-of-band signals are inaccessible to the user. The term is also used more generally, for example of computer data files that include both literal data, and metadata and/or instructions for how to process the literal data. Telephony When dialing from a land-line telephone, the telephone number is encoded and transmitted across the telephone line in form of dual-tone multi-frequency signaling (DTMF). The tones control the telephone system by instructing the telephone switch where to route the call. These control tones are sent over the same channel, the copper wire, and in the frequency range (300 Hz to 3.4 kHz) as the audio of the teleph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Binary-to-text Encoding
A binary-to-text encoding is encoding of data in plain text. More precisely, it is an encoding of binary data in a sequence of printable characters. These encodings are necessary for transmission of data when the channel does not allow binary data (such as email or NNTP) or is not 8-bit clean. PGP documentation () uses the term "ASCII armor" for binary-to-text encoding when referring to Base64. Overview The basic need for a binary-to-text encoding comes from a need to communicate arbitrary binary data over preexisting communications protocols that were designed to carry only English language human-readable text. Those communication protocols may only be 7-bit safe (and within that avoid certain ASCII control codes), and may require line breaks at certain maximum intervals, and may not maintain whitespace. Thus, only the 94 printable ASCII characters are "safe" to use to convey data. Description The ASCII text-encoding standard uses 7 bits to encode characters. With this it is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
8BITMIME
The Simple Mail Transfer Protocol (SMTP) is an Internet standard communication protocol for electronic mail transmission. Mail servers and other message transfer agents use SMTP to send and receive mail messages. User-level email clients typically use SMTP only for sending messages to a mail server for relaying, and typically submit outgoing email to the mail server on port 587 or 465 per . For retrieving messages, IMAP (which replaced the older POP3) is standard, but proprietary servers also often implement proprietary protocols, e.g., Exchange ActiveSync. SMTP's origins began in 1980, building on concepts implemented on the ARPANET since 1971. It has been updated, modified and extended multiple times. The protocol version in common use today has extensible structure with various extensions for authentication, encryption, binary data transfer, and internationalized email addresses. SMTP servers commonly use the Transmission Control Protocol on port number 25 (for plaintext) and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linefeed
Newline (frequently called line ending, end of line (EOL), next line (NEL) or line break) is a control character or sequence of control characters in character encoding specifications such as ASCII, EBCDIC, Unicode, etc. This character, or a sequence of characters, is used to signify the end of a line of text and the start of a new one. History In the mid-1800s, long before the advent of teleprinters and teletype machines, Morse code operators or telegraphists invented and used Morse code prosigns to encode white space text formatting in formal written text messages. In particular the Morse prosign (mnemonic reak ext) represented by the concatenation of literal textual Morse codes "B" and "T" characters sent without the normal inter-character spacing is used in Morse code to encode and indicate a ''new line'' or ''new section'' in a formal text message. Later, in the age of modern teleprinters, standardized character set control codes were developed to aid in white space ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High ASCII
Extended ASCII is a repertoire of character encodings that include (most of) the original 96 ASCII character set, plus up to 128 additional characters. There is no formal definition of "extended ASCII", and even use of the term is sometimes criticized, because it can be mistakenly interpreted to mean that the American National Standards Institute (ANSI) had updated its standard to include more characters, or that the term identifies a single unambiguous encoding, neither of which is the case. The ISO standard ISO 8859 was the first international standard to formalise a (limited) expansion of the ASCII character set: of the many language variants it encoded, ISO 8859-1 ("ISO Latin 1")which supports most Western European languages is best known in the West. There are many other extended ASCII encodings (more than 220 DOS and Windows codepages). EBCDIC ("the other" major character code) likewise developed many extended variants (more than 186 EBCDIC codepages) over the decades. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Control Character
In computing and telecommunication, a control Character (computing), character or non-printing character (NPC) is a code point (a number) in a character encoding, character set, that does not represent a written symbol. They are used as in-band signaling to cause effects other than the addition of a symbol to the text. All other characters are mainly printing, printable, or graphic characters, except perhaps for the "space (punctuation), space" character (see ASCII printable characters). History Prosigns for Morse code, Procedural signs in Morse code are a form of control character. A form of control characters were introduced in the 1870 Baudot code: NUL and DEL. The 1901 Murray code added the carriage return (CR) and line feed (LF), and other versions of the Baudot code included other control characters. The bell character (BEL), which rang a bell to alert operators, was also an early Teleprinter, teletype control character. Control characters have also been called "format ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
8-bit Clean
''8-bit clean'' is an attribute of computer systems, communication channels, and other devices and software, that handle 8-bit character encodings correctly. Such encoding include the ISO 8859 series and the UTF-8 encoding of Unicode. History Until the early 1990s, many programs and data transmission channels were character-oriented and treated some characters, e.g., ETX, as control characters. Other assumed a stream of seven-bit characters, with values between 0 and 127; for example, the ASCII standard used only seven bits per character, avoiding an 8-bit representation in order to save on data transmission costs. On computers and data links using 8-bit bytes this left the top bit of each byte free for use as a parity, flag bit, or meta data control bit. 7-bit systems and data links are unable to directly handle more complex character codes which are commonplace in non-English-speaking countries with larger alphabets. Binary files of octets cannot be transmitted through 7 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Email
Electronic mail (email or e-mail) is a method of exchanging messages ("mail") between people using electronic devices. Email was thus conceived as the electronic ( digital) version of, or counterpart to, mail, at a time when "mail" meant only physical mail (hence '' e- + mail''). Email later became a ubiquitous (very widely used) communication medium, to the point that in current use, an email address is often treated as a basic and necessary part of many processes in business, commerce, government, education, entertainment, and other spheres of daily life in most countries. ''Email'' is the medium, and each message sent therewith is also called an ''email.'' The term is a mass noun. Email operates across computer networks, primarily the Internet, and also local area networks. Today's email systems are based on a store-and-forward model. Email servers accept, forward, deliver, and store messages. Neither the users nor their computers are required to be online simult ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
R2 Signalling
Signalling System R2 is a signalling protocol for telecommunications that was in use from the 1960s mostly in Europe, and later also in Latin America, Asia, and Australia, to convey exchange information between two telephone switching systems for establishing a telephone call via a telephone trunk.ITU-T Recommendation Q.400-Q.490 - Specifications of Signalling System R2 It is suitable for signaling on analog as well as digital circuits. R2 signaling specifications were first published by the International Telegraph and Telephone Consultative Committee (CCITT) in ITU White Book Volume VI of 1969,IVth Plenary Assembly (Mar Del Plata, 23 September-25 October 1968), White Book Volume VI, ''Telephone Signaling and Switching'', Recommendations Series Q, ITU 1969. and are maintained by the [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transmission System
:''See Transmission (mechanics) for a car's transmission system'' In telecommunications, a transmission system is a system that transmits a signal from one place to another. The signal can be an Signal (electrical engineering), electrical, optical or Radio wave, radio signal. Some transmission systems contain multipliers, which amplify a signal prior to re-transmission, or Regenerator (telecommunication), regenerators, which attempt to reconstruct and re-shape the coded message before re-transmission. One of the most widely used transmission system technologies in the Internet and the PSTN is SONET. Also, transmission system is the medium through which data is transmitted from one point to another. Examples of common transmission systems people use everyday are: the internet, mobile network, cordless cables, etc. See also * Communications satellite * Submarine communications cable a cable on the sea bed. Notes Telecommunications systems In order to propel the vehicle, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
