Avionics system architects have a wide variety of commercial off the shelf (COTS) choices for networking technologies. The challenge facing many system architects is choosing a cost effective technology that satisfies the functional requirements of the system. This paper provides insight into some of the key architectural features of two of the most popular emerging networking technologies used in avionics today, namely, Fibre Channel and Ethernet. An overview of each architectural feature is provided along with a discussion of the system-level benefits associated with the feature. A new approach called high speed 1553 is also explored. The goal of this paper is not to evaluate these technologies against an arbitrary set of criteria to determine which is better for avionics systems, but rather to provide insight into the benefits of each technology. In reality, no one networking architecture will be “best” for all applications. Each application will contain its own unique requirements that will shape the selection decision. In many cases, the optimal solution may be a combination of several different networking technologies.

Avionics Networking Technology

MIL-STD-1553 has served the needs of military system integrators for over 30 years, particularly in the area of command and control applications. Nevertheless, contemporary applications such as high-speed digitized sensors, file transfers, processor clusters, and displays require much higher data rates than 1553’s 1Mb/s. For some environments, particularly for legacy aircraft, the optional solution is to transmit faster data rates over existing 1553 buses. However, there are other applications that can accommodate and benefit by the deployment of gigabit or multi-gigabit copper or optical switched fabric networks. In addition to MIL-STD-1553, this paper presents and comments about several avionics networking technologies including High-Speed 1553, Fibre Channel, Gigabit Ethernet, and ARINC 664, a form of profiled Ethernet.

Buses and Networks for Contemporary Avionics

In an effort to reap the benefits of standardization for data recorder file formats, the Range Commanders Council (RCC) and others in the US Air Force instrumentation community developed the IRIG 106 Chapter 10 standard. IRIG 106 Chapter 10 provides interoperability for such applications as test range telemetry, flight test instrumentation, mission recorders, video/data servers; surveillance and reconnaissance; health and usage monitoring; mission planning, debriefing, and training; and flight operations. In addition to file formats, Chapter 10 defines the operation of various recorder and removable media (data cartridge) interfaces. IRIG 106 Chapter 10 includes specific formats for several types of flight data, including MIL-STD-1553 buses, PCM, analog, computer-generated data, images, discretes, UARTs, IEEE 1394, parallel, IRIG time, video, and voice. In addition, Chapter 106 provides standardization of time bases.

IRIG 106 Chapter 10 Standardizes MIL-STD-1553 Data Recording

For contemporary avionics design, there’s a need to strategically allocate engineering resources without increasing time to market. This environment has engendered an increasing reliance on Commercial-off-the-Shelf (COTS) hardware and software, with a demand for total solutions that may be leveraged over a range of applications. This entails the needs for ruggedized hardware, along with re-usable high-level software tools. The COTS paradigm includes a focus on cost effectiveness and high reliability, along with obsolescence and end-of-life issues for both cards and components.

Total COTS Solutions for Embedded 1553

Fibre Channel is a high-speed networking technology deployed on a number of military/aerospace platforms and programs. These include F-18E/F, F-16, F-35, B1-B, B-2, E-2D, the Apache Longbow and MMH helicopters, and AESA Radar. Applications for Fibre Channel include mission computers, processor and DSP clusters; data storage; video processing, distribution, and displays; sensors such as radar, FLIR, and video; serial backplanes and IFF.

Test, Simulation, and Integration of Fibre Channel Networked Systems

The growing interest in Ethernet for Military applications has been driven by the networking technology’s commercial success. Such ubiquity has resulted in readily available COTS software and hardware with attractive cost and performance characteristics. Commercial technology does not always meet military constraints, which has limited the military use of Ethernet to non-mission-critical applications. Fast Ethernet has already been deployed in several military systems, but designers want to take advantage of Gigabit Ethernet performance for critical functions such as sensor interfaces, display processing, digital map servers, and data recorders. The transition to Gigabit Ethernet in the Battlespace calls for designers to examine network performance requirements closely.

Adapting Gigabit Ethernet to Military Systems

Ethernet’s widespread use and longevity have resulted in an abundance of COTS hardware and network application software for military use. 10/100 Mbps Ethernet has been deployed for years and now Gigabit Ethernet is being designed into both system upgrades and new weapon systems.

Military Gigabit Ethernet: A TOE-to-TOE Comparison