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Packet Radio
In digital radio, packet radio is the application of packet switching techniques to digital radio communications. Packet radio uses a packet switching protocol as opposed to circuit switching or message switching protocols to transmit digital data via a radio communication link. Packet radio can be differentiated from other digital radio switching schemes by the following attributes: * Transmitted data is broken into packets, each of which contains a destination (and typically the source) address * A transmitted message may be broken into a sequence of packets before transmission, which are then re-assembled into the original message upon reception * Packets for multiple destinations can be transmitted on the same radio link in an asynchronous fashion * A packet may be addressed to all possible recipients rather than a specific one (broadcast) * A packet may be stored and subsequently forwarded towards its destination by a network node This is very similar to how packets of d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Improved Layer 2 Protocol
IL2P (Improved Layer 2 Protocol) is a data link layer protocol originally derived from layer 2 of the X.25 protocol suite and designed for use by amateur radio operators. It is used exclusively on amateur packet radio networks. IL2P occupies the data link layer, the second layer of the OSI model. It is responsible for establishing link-layer connections, transferring data encapsulated in frames between nodes, and detecting errors introduced by the communications channel. The Improved Layer 2 Protocol (IL2P) was created by Nino Carrillo, KK4HEJ, based on AX.25 version 2.0 and implements Reed Solomon Forward Error Correction for greater accuracy and throughput than either AX.25 or FX.25. Specifically, in order to achieve greater stability on link speeds greater than 1200 baud. IL2P can be used with a variety of modulation methods including AFSK and GFSK. Thdirewolf software TNCcontains the first open source implementation of the protocol. IL2P Specification The IL2P draft ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tnc2400-stardado
TNC may refer to: Computers * Triangular network coding, a packet coding scheme * Trusted Network Connect, an open architecture for computer network access control Education * Trevecca Nazarene College, now called Trevecca Nazarene University, Nashville, Tennessee, U.S. * Turkmen National Conservatory, a music conservatory in Ashgabat, Turkmenistan Science and medicine * Tenascin C or TN-C, a protein encoded by the ''TNC'' gene * Thymic nurse cells Arts, entertainment, and media * Teatre Nacional de Catalunya, a public theatre in Barcelona, Catalonia, Spain * Television Nishinippon Corporation, a TV station in Fukuoka, Japan * Telenovela Channel, a telenovela-based cable channel in the Philippines * ''The New Criterion'', a monthly literary magazine based in New York City, New York, U.S. * Theater for the New City, New York City, New York, U.S. Other uses * Terminal node controller, a device used by amateur radio operators * The Nature Conservancy, an environmental organizat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mobile Communications
Mobile telephony is the provision of telephone services to phones which may move around freely rather than stay fixed in one location. Telephony is supposed to specifically point to a voice-only service or connection, though sometimes the line may blur. Mobile phones connect to a terrestrial cellular network of base stations (cell sites), whereas satellite phones connect to orbiting satellites. Both networks are interconnected to the public switched telephone network (PSTN) to allow any phone in the world to be dialed. In 2010 there were estimated to be five billion mobile cellular subscriptions in the world. History According to internal memos, American Telephone & Telegraph discussed developing a wireless phone in 1915, but were afraid that deployment of the technology could undermine its monopoly on wired service in the U.S. Public mobile phone systems were first introduced in the years after the Second World War and made use of technology developed before an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Norman Abramson
Norman Manuel Abramson (April 1, 1932biography from (1964) – December 1, 2020) was an American engineer and computer scientist, most known for developing the system for wireless computer communication. Early life Abramson was born on April 1, 1932 in Boston, Massachusetts, to immigrant Jewish parents Edward and Esther. His father was born in Lithuania, and worked in commercial photography. His mother was born in Ukraine, and managed the house. He wa ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Communication Channel
A communication channel refers either to a physical transmission medium such as a wire, or to a logical connection over a multiplexed medium such as a radio channel in telecommunications and computer networking. A channel is used for information transfer of, for example, a digital bit stream, from one or several '' senders'' to one or several '' receivers''. A channel has a certain capacity for transmitting information, often measured by its bandwidth in Hz or its data rate in bits per second. Communicating an information signal across distance requires some form of pathway or medium. These pathways, called communication channels, use two types of media: Transmission line (e.g. twisted-pair, coaxial, and fiber-optic cable) and broadcast (e.g. microwave, satellite, radio, and infrared). In information theory, a channel refers to a theoretical ''channel model'' with certain error characteristics. In this more general view, a storage device is also a communication channel, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telecommunications Network
A telecommunications network is a group of nodes interconnected by telecommunications links that are used to exchange messages between the nodes. The links may use a variety of technologies based on the methodologies of circuit switching, message switching, or packet switching, to pass messages and signals. Multiple nodes may cooperate to pass the message from an originating node to the destination node, via multiple network hops. For this routing function, each node in the network is assigned a network address for identification and locating it on the network. The collection of addresses in the network is called the address space of the network. Examples of telecommunications networks include computer networks, the Internet, the public switched telephone network (PSTN), the global Telex network, the aeronautical ACARS network, and the wireless radio networks of cell phone telecommunication providers. Network structure In general, every telecommunications network conceptu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Network Topology
Network topology is the arrangement of the elements ( links, nodes, etc.) of a communication network. Network topology can be used to define or describe the arrangement of various types of telecommunication networks, including command and control radio networks, industrial fieldbusses and computer networks. Network topology is the topological structure of a network and may be depicted physically or logically. It is an application of graph theory wherein communicating devices are modeled as nodes and the connections between the devices are modeled as links or lines between the nodes. Physical topology is the placement of the various components of a network (e.g., device location and cable installation), while logical topology illustrates how data flows within a network. Distances between nodes, physical interconnections, transmission rates, or signal types may differ between two different networks, yet their logical topologies may be identical. A network’s physical topology ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Broadcasting (computing)
In computer networking, telecommunication and information theory, broadcasting is a method of transferring a message to all recipients simultaneously. Broadcasting can be performed as a high-level operation in a program, for example, broadcasting in Message Passing Interface, or it may be a low-level networking operation, for example broadcasting on Ethernet. All-to-all communication is a computer communication method in which each sender transmits messages to all receivers within a group. In networking this can be accomplished using broadcast or multicast. This is in contrast with the point-to-point method in which each sender communicates with one receiver. Addressing methods There are four principal addressing methods in the Internet Protocol: Overview In computer networking, broadcasting refers to transmitting a packet that will be received by every device on the network. In practice, the scope of the broadcast is limited to a broadcast domain. Broadcasting is the m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telecommunication Circuit
A telecommunication circuit is a path in a telecommunications network used to transmit information. Circuits have evolved over time from generally being built on physical connections between individual hardware cables, as in an analog phone switch, to virtual circuits established over packet switching networks. Definitions A telecommunication circuit may be defined as follows: * The complete path between two terminals over which one-way or two-way communications may be provided. * An electronic path between two or more points, capable of providing a single or multiple communication channels. * An electronic closed-loop path among two or more points used for signal transfer. In operational terms, a telecommunication circuit may be capable of transmitting information in only one direction (''simplex'' circuit), or it may be bi-directional (''duplex'' circuit). Bi-directional circuits may support half- duplex operation, when only one end of the channel transmits at any one tim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Baudot Code
The Baudot code is an early character encoding for telegraphy invented by Émile Baudot in the 1870s. It was the predecessor to the International Telegraph Alphabet No. 2 (ITA2), the most common teleprinter code in use until the advent of ASCII. Each character in the alphabet is represented by a series of five bits, sent over a communication channel such as a telegraph wire or a radio signal by asynchronous serial communication. The symbol rate measurement is known as baud, and is derived from the same name. History Baudot code (ITA1) In the below table, Columns I, II, III, IV, and V show the code; the Let. and Fig. columns show the letters and numbers for the Continental and UK versions; and the sort keys present the table in the order: alphabetical, Gray and UK Baudot developed his first multiplexed telegraph in 1872 [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Teleprinter
A teleprinter (teletypewriter, teletype or TTY) is an electromechanical device that can be used to send and receive typed messages through various communications channels, in both point-to-point and point-to-multipoint configurations. Initially they were used in telegraphy, which developed in the late 1830s and 1840s as the first use of electrical engineering, though teleprinters were not used for telegraphy until 1887 at the earliest. The machines were adapted to provide a user interface to early mainframe computers and minicomputers, sending typed data to the computer and printing the response. Some models could also be used to create punched tape for data storage (either from typed input or from data received from a remote source) and to read back such tape for local printing or transmission. Teleprinters could use a variety of different communication media. These included a simple pair of wires; dedicated non-switched telephone circuits (leased lines); switched ne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Morse Code
Morse code is a method used in telecommunication to encode text characters as standardized sequences of two different signal durations, called ''dots'' and ''dashes'', or ''dits'' and ''dahs''. Morse code is named after Samuel Morse, one of the inventors of the telegraph. International Morse code encodes the 26 basic Latin letters through , one accented Latin letter (), the Arabic numerals, and a small set of punctuation and procedural signals ( prosigns). There is no distinction between upper and lower case letters. Each Morse code symbol is formed by a sequence of ''dits'' and ''dahs''. The ''dit'' duration is the basic unit of time measurement in Morse code transmission. The duration of a ''dah'' is three times the duration of a ''dit''. Each ''dit'' or ''dah'' within an encoded character is followed by a period of signal absence, called a ''space'', equal to the ''dit'' duration. The letters of a word are separated by a space of duration equal to three ''dits' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
