Avionics are the electronic systems used on aircraft, artificial satellites, and spacecraft. Avionic systems include communications, navigation, the display and management of multiple systems, and the hundreds of systems that are fitted to aircraft to perform individual functions. These can be as simple as a searchlight for a police helicopter or as complicated as the tactical system for an airborne early warning platform. The term avionics is a portmanteau of the words aviation and electronics.
In computer architecture, a bus is a communication system that transfers data between components inside a computer, or between computers. This expression covers all related hardware components and software, including communication protocols.
A line-replaceable unit (LRU), lower line-replaceable unit (LLRU), line-replaceable component (LRC), or line-replaceable item (LRI) is a modular component of an airplane, ship or spacecraft that is designed to be replaced quickly at an operating location. The different lines (distances) are essential for logistics planning and operation. An LRU is usually a sealed unit such as a radio or other auxiliary equipment. LRUs are typically assigned logistics control numbers (LCNs) or work unit codes (WUCs) to manage logistics operations.
A vehicle bus is a specialized internal communications network that interconnects components inside a vehicle. Special requirements for vehicle control such as assurance of message delivery, of non-conflicting messages, of minimum time of delivery, of low cost, and of EMF noise resilience, as well as redundant routing and other characteristics mandate the use of less common networking protocols. Protocols include Controller Area Network (CAN), Local Interconnect Network (LIN) and others. Conventional computer networking technologies are rarely used, except in aircraft, where implementations of the ARINC 664 such as the Avionics Full-Duplex Switched Ethernet are used. Aircraft that use AFDX include the B787, the A400M and the A380.
Aeronautical Radio, Incorporated (ARINC), established in 1929, is a major provider of transport communications and systems engineering solutions for eight industries: aviation, airports, defense, government, healthcare, networks, security, and transportation. ARINC has installed computer data networks in police cars and railroad cars and also maintains the standards for line-replaceable units.
An air data computer (ADC) is an essential avionics component found in modern glass cockpits. This computer, rather than individual instruments, can determine the calibrated airspeed, Mach number, altitude, and altitude trend data from an aircraft's pitot-static system. In some very high speed aircraft such as the Space Shuttle, equivalent airspeed is calculated instead of calibrated airspeed.
In aviation, ACARS is a digital datalink system for transmission of short messages between aircraft and ground stations via airband radio or satellite. The protocol was designed by ARINC and deployed in 1978, using the Telex format. More ACARS radio stations were added subsequently by SITA.
A bus analyzer is a type of a protocol analysis tool, used for capturing and analyzing communication data across a specific interface bus, usually embedded in a hardware system. The bus analyzer functionality helps design, test and validation engineers to check, test, debug and validate their designs throughout the design cycles of a hardware-based product. It also helps in later phases of a product life cycle, in examining communication interoperability between systems and between components, and clarifying hardware support concerns.
Avionics Full-Duplex Switched Ethernet (AFDX) is a data network, patented by international aircraft manufacturer Airbus, for safety-critical applications that utilizes dedicated bandwidth while providing deterministic quality of service (QoS). AFDX is a worldwide registered trademark by Airbus. The AFDX data network is based on Ethernet technology using commercial off-the-shelf (COTS) components. The AFDX data network is a specific implementation of ARINC Specification 664 Part 7, a profiled version of an IEEE 802.3 network per parts 1 & 2, which defines how commercial off-the-shelf networking components will be used for future generation Aircraft Data Networks (ADN). The six primary aspects of an AFDX data network include full duplex, redundancy, determinism, high speed performance, switched and profiled network.
ARINC 429, "Mark33 Digital Information Transfer System (DITS)," is also known as the Aeronautical Radio INC. (ARINC) technical standard for the predominant avionics data bus used on most higher-end commercial and transport aircraft. It defines the physical and electrical interfaces of a two-wire data bus and a data protocol to support an aircraft's avionics local area network.
Aircraft Data Network (ADN) is a concept introduced by the Airlines Electronics Engineering Committee (AEEC) in the ARINC 664 Specification. The specification proposes data networking standards recommended for use in commercial aircraft installations. The standards provide a means to adapt COTS networking standards to an aircraft environment. It refers to devices such as bridges, switches, routers and hubs and their use in an aircraft environment. This equipment, when installed in a network topology, can provide effective data transfer and overall avionics performance. The ARINC 664 specification refers extensively to the set of data networking standards developed by the Internet community and IEEE. The specification also applies the concepts of Open Systems Interconnection (OSI) standards.
ARINC 661 is a standard which aims to normalize the definition of a Cockpit Display System (CDS), and the communication between the CDS and User Applications (UA) which manage aircraft avionics functions. The GUI definition is completely defined in binary Definition Files (DF).
Integrated modular avionics (IMA) are real-time computer network airborne systems. This network consists of a number of computing modules capable of supporting numerous applications of differing criticality levels.
ARINC 653 is a software specification for space and time partitioning in safety-critical avionics real-time operating systems (RTOS). It allows the hosting of multiple applications of different software levels on the same hardware in the context of an Integrated Modular Avionics architecture.
ARINC 818: Avionics Digital Video Bus (ADVB) is a video interface and protocol standard developed for high bandwidth, low latency, uncompressed digital video transmission in avionics systems. The standard, which was released in January 2007, has been advanced by ARINC and the aerospace community to meet the stringent needs of high performance digital video. The specification was updated and ARINC 818-2 was released in December 2013, adding a number of new features, including link rates up to 32X fibre channel rates, channel-bonding, switching, field sequential color, bi-directional control, and data only links.
High Frequency Data Link (HFDL) is an ACARS communications media used to exchange data such as Aeronautical Operational Control (AOC) messages, Controller Pilot Data Link Communications (CPDLC) messages and Automatic Dependent Surveillance (ADS) messages between aircraft end-systems and corresponding ground-based HFDL ground stations. Using the unique propagation characteristics of high-frequency radio waves, the ground stations provide data link communications to properly equipped aircraft operating anywhere in the world. The result, pilots can always communicate with someone on the ground.
SwiftBroadband is an IP-based packet-switched communications network that provides a symmetric ‘always-on’ data connection of up to 650 kbit/s per channel for aircraft globally except for the polar regions, using the Inmarsat satellite constellation.
CANalyzer is an analysis software tool from Vector Informatik GmbH. This development software is widely used, primarily by automotive and electronic control unit suppliers, to analyze the data traffic in serial bus systems. The most relevant bus systems here are CAN, LIN, FlexRay, Ethernet and MOST as well as CAN-based protocols such as J1939, CANopen, ARINC 825 and many more.
Bus monitoring is a term used in flight testing when capturing data from avionics buses and networks in data acquisition telemetry systems. Commonly monitored avionics buses include
The ARINC 629 computer bus was introduced in May 1995 and is used on the Boeing 777, and Airbus aircraft. The ARINC 629 bus operates as a multiple-source, multiple-sink system; each terminal can transmit data to, and receive data from, every other terminal on the data bus. This allows much more freedom in the exchange of data between units in the avionics system. ARINC 629 has the ability to accommodate up to a total of 128 terminals on a data bus and supports a data rate of 2 Mbit/s.
