What are MIL-STD-1553-compliant Connectors and Assemblies?
Meet the Connector: MIL-STD-1553-compliant Connectors and Assemblies
MIL-STD-1553 is a military standard that defines the mechanical, electrical, and functional characteristics of a serial data bus, with the goal of reliably moving data. Also known as Milbus, this standard has been incorporated in nearly every type of U.S. military vehicle built in the last 50 years because designers know connectors compliant to MIL-STD-1553 work, according to Brian Conway, product manager at Cinch Connectivity Solutions. It was originally designed as an avionic serial multiplex data bus for military aircraft and has become common in space applications such as on-board data handling subsystems for spacecraft, the ISS, and the James Webb space telescope. MIL-STD-1553 is now commonly used for integrating defense and space systems, and increasingly in the commercial aerospace sector.
Evolution of the Standard
The U.S. Air Force specifications created for an avionics data bus became an official Air Force standard in 1973 and was first used in F-16 Falcon fighter jets. The bus and the MIL-STD-1553 specification were later adopted by the other branches of the U.S. Armed Forces and became the basis for bus standards used in the United Kingdom and by the North Atlantic Treaty Organization (NATO). The National Aeronautics and Space Administration (NASA) also standardized that bus for spacecraft on-board data handling (OBDH) systems.
The first revision, MIL-STD-1553A, followed in 1975. Differences in how the revision was being implemented by suppliers led to product incompatibilities. To address this, in 1978 MIL-STD-1553B was issued, allowing manufacturing variations but specifying strict electrical interfaces.
MIL-STD-1553 Hardware
The MIL-STD-1553 system is comprised of a bus controller (BC), a remote terminal (RT), and bus monitor (BM). The BC is the only part of the system that can initiate a data transfer, and this is a key factor in the system’s reliability.
A PEI-Genesis blog post explains that data bus couplers act as interface points on the data bus and distribute signals among various subsystems. The standard outlines a dual-redundant, balanced line physical layer; a bus controller initiates all communications. Each bus supports up to 31 remote terminals that provide input and output interfaces to the data bus, and one or more bus monitors that passively collect data without affecting the bus operations. These devices are connected to the bus through tributaries called stubs. Additional components that are key to the standard include terminators that maintain signal integrity by absorbing signals that reach the bus end, preventing reflection and ensuring stable communication; durable, shielded twisted pair cables and specialized connectors designed to withstand the environmental challenges of military operations; and adapters, interface devices that facilitate communication between avionics systems in aerospace and military applications.
Cinch Trompeter connectors, cables, terminators, and adapters from PEI-Genesis are engineered to meet the rigorous standards of MIL-STD-1553 set forth by the U.S. Department of Defense for databus communication systems in military and aerospace applications.
MIL-STD-1553B has multiple roles
In flight control systems (FCS), MIL-STD-1553B’s high-speed, reliable digital bus ensures rapid and error-free data transmission for dynamic flight stability, due to the consolidation of cockpit commands with sensor feedback that directly facilitates real-time, automated adjustments to flight parameters.
A unified communication framework seamlessly consolidates data from GPS, radar, and inertial navigation systems. Such integration enables the aircraft to calculate its position, direction, and velocity with accuracy. Furthermore, the standard’s robust error-checking mechanisms help to ensure that positioning data is consistently reliable.
In avionic navigation systems, MIL-STD-1553B provides a unified communication framework to seamlessly consolidate data from GPS, radar, and inertial navigation systems. This enables the aircraft to calculate its position, direction, and velocity with accuracy. Furthermore, the standard’s robust error-checking mechanisms help ensure the ongoing reliability of positioning data.
Radiall’s RTX screw-on miniature connectors operate at low frequency DC-5 MHz and are designed to be used with digital data bus defined by MIL-STD-1553B standard in digital avionic equipment. RTX interface complies to AECMA EN3716 standard.
Axon’ Cable specializes in the design and manufacture of all components used in data transmission systems in compliance with MIL-STD-1553. From communication systems to in-flight control devices, signals are transmitted through these reliable MIL-STD-1553 compliant links. They offer high data security, signal integrity, good electromagnetic protection, weight and space saving, as well as a fast diagnostic of all equipment connected to the bus.
Design Notes
Standards: Extensive testing and qualification processes ensure compliance with MIL-STD-1553B requirements, providing assurance of interoperability and compatibility with other components within the databus network.
Installation: Requires dual redundant systems with two signal paths, one main signal transmission line plus a backup. All connectors and RF cables, which collectively form the primary physical layer of the system, must strictly meet all requirements.
Transmission protocol: Time-division multiplexing (TDM).
Materials: High quality materials to ensure high reliability and twinax cables (featuring a twisted pair of wires) cancel electromagnetic fields to create RF shielding.
Environmental properties: Equipment must be rugged and able to hold up to harsh environments, including temperature ranges and life, shock, and moisture resistance. Polarization, keying, and optional hermetic sealing guarantee proper mating and prevent signal loss or corruption.
Electrical properties: Equipment operates at low frequencies, less than 500 megahertz (MHz).
Markets and Applications
Military and Aerospace, Transportation
Military aircraft, land, and sea vehicles; defense and space system integration; commercial aerospace
Suppliers
Cinch Connectivity Solutions, PEI-Genesis, Axon’ Cable, DigiKey, Mouser Electronics, TE Connectivity, Radiall, United Electric Industries (AMETEK), Amphenol, Excalibur Systems, and Miles Tek.
Like this article? Check out our other Meet the Connector articles to learn more about the world of interconnects.
To learn more about the companies mentioned in this article, visit the Preferred Supplier pages for Cinch Connectivity Solutions, PEI-Genesis, Axon’ Cable, DigiKey, Mouser Electronics, TE Connectivity, Radiall, and United Electric Industries (AMETEK).
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