MIL-STD-1553's longevity is well deservedStory
August 11, 2010
The MIL-STD-1553 databus protocol still holds a strong position on military platforms, even after almost 40 years of deployment. The impetus: deterministic, real-time capabilities and reliability, in addition to a vast installed base. These ensure that 1553 will be around for quite a long time.
After almost 40 years of deployment, the MIL-STD-1553 databus protocol still holds a strong position on military platforms. How can a technology that old still have a place in mission-critical systems when so many newer databus protocols have appeared on the scene? Real-time deterministic capabilities and reliability, coupled with a vast installed base, have ensured 1553’s ubiquity. Current and future military platforms will engage newer databus protocols, but 1553 will still be around for quite some time.
The evolution of 1553
In 1968, the Society of Automotive Engineers (SAE), a technical body of military and industrial members, established a subcommittee to define a serial data bus to meet the needs of the military avionics community. Several years of military and government reviews and changes led to the August 1973 release of MIL-STD-1553, with the U.S. Air Force’s F-16 as the initial standard’s primary user.
After some “real world” experience, program managers soon realized that further definitions and additional capabilities to the standard were needed. The SAE group spent three years of concentrated effort to produce the follow-on standard, MIL-STD-1553B, which was released in 1978. At that point, the government decided to freeze the standard at the “B” level to allow component manufacturers to develop products that could be immediately deployed. And today, the venerable 1553B standard is still in use.
A look inside MIL-STD-1553
The MIL-STD-1553 time division multiplexing data bus is the most ubiquitous military data bus today, used in platforms where data integrity and system reliability are critical. MIL-STD-1553 defines a method that permits digital signal communications along a common databus network with the real-time characteristics of a direct cable connection. It saves the weight and expense of miles of individual cables used to connect subsystems such as aircraft control surfaces and navigation controls.
By defining the standards for the functional, mechanical, and electrical characteristics of the serial data bus commonly used in the avionics of military aircraft, MIL-STD-1553 has been utilized to integrate computers into aircraft platforms and provide greatly enhanced reliability and performance while reducing costs.
Since its inception, MIL-STD-1553 has found numerous applications. Notice 2 to the standard has removed all references to aircraft or airborne so as to not limit its use to aircraft platforms.
Space and military venues
Although the standard has been applied to satellites and payloads within the space shuttle and International Space Station realms, its military applications are the most numerous and far ranging. It is employed on large transports, submarines, aircraft refuelers, bombers, tactical fighters, and helicopters. It is even contained within missiles and serves in some cases as the primary interface between the aircraft and missile. The U.S. Navy has applied the data bus to accommodate both surface and subsurface ships. And the U.S. Army utilizes 1553 in its helicopters, tanks, and howitzers.
Additionally, the central role that the 1553 standard plays in weapons delivery will remain strong, even with the latest fighters. For example, the Joint Strike Fighter F-35’s avionics data bus is not limited to MIL-STD-1553B, but also includes IEEE1394B Firewire and Fibre Channel for use in flight control and data display.
Because of its longevity, MIL-STD-1553 products, reference guides, and tutorials are readily available. Rugged COTS MIL-STD-1553 interface hardware, such as the RXMC1553 XMC.0 Mezzanine Card from GE Intelligent Platforms, are also building the 1553 ecosystem. Depicted in Figure 1, the XMC combines high-speed encoding and decoding and intelligent protocol processing with advanced Application Programming Interface (API) software that reduces 1553 application development time.
Figure 1: The RXMC1553 XMC.0 Mezzanine Card from GE Intelligent Platforms
(Click graphic to zoom by 1.9x)
Transportation and government
MIL-STD-1553 products have even found their way into transportation applications such as San Francisco’s Bay Area Rapid Transit (BART) system. Other non-military applications include nuclear reactors and manufacturing production lines.
Meanwhile, government adoption of MIL-STD-1553B includes acceptance and implementation by the North Atlantic Treaty Organization (NATO) and many foreign governments. The UK has issued Def Stan 00-18 (Part 2), and NATO has published STANAG 3838 AVS, both of which are versions of MIL-STD-1553B.
Looking ahead: Is MIL-STD-1553 a panacea?
Higher-performance data bus technologies such as IEEE1394B Firewire, Fibre Channel, and GbE are moving into areas once solely occupied by MIL-STD-1553. Today’s modern aircraft use a mix of high-performance data buses and 1553. These newer technologies bring higher network speeds than 1553’s 1 Mbps and are well suited for high-bandwidth applications such as video transmission and sensor displays, coexisting with MIL-STD-1553 but not supplanting it completely.
The 1553 protocol’s extensive use in platforms and applications with service lives spanning decades will ensure the standard will be supported and employed by the military, government, transportation, and commercial sectors for years to come.
To learn more, e-mail Duncan at [email protected]