Product Focus: Databus Technology

Just a year ago, it appeared that aircraft databus technology was poised to break into the 200 Mbps range, multiplying traditional data communications rates by 100-fold or more. Initial tests were promising, but the technical challenge of making such a capability operational proved daunting. Earlier this year, the United States Air Force turned off the spigot on its main effort in that area, sending the contractor working on the program — Edgewater Computer Systems of Ottawa, Ontario — to look for other sources of funding for what is known as Extended 1553 (E1553).

Industry observers noted that E1553, which started at 200 Mbps and was envisioned to reach 500 Mbps, tried to do too much too fast. Said one senior executive: "We’re not sure where Extended 1553 is going. What’s happened is that this has turned into a science experiment… no working hardware, no projected schedule, no programs committed to it."

"We have seen over the last quite a few years the failed attempts to get higher speed out of 1553," noted George Sponsler, vice president of Excalibur Systems, Elmont, N.Y. 1553 remains important "for what it does best, which is command and control. But don’t ask it to pass a lot of data," he said.

Rather than attempting to take a revolutionary leap into high-speed high-bandwidth systems, the industry looks like it will settle back into an evolutionary mode in which speed and bandwidth will increase in a more measured way, but still be fast enough to accommodate the new functionality expected for next-generation civil and military aircraft.

"The industry will now be looking at solutions that are faster than 1 Mbps but nowhere near 200 Mbps," said Arnie Markowitz, vice president of sales for API Nanotronics, the parent company of National Hybrid Inc. (NHI). "1553 is a very successful solution and will continue to be used even on the latest developments from Airbus and Boeing."

Bus Alternatives

Airbus, for example, employs the ARINC 664 AFDX (Avionics Full-Duplex Switched Ethernet) deterministic data network on its latest aircraft, but still makes extensive use of traditional 1553 for critical systems such as ailerons, rudders and other control surfaces.

Boeing Commercial Airplanes is also employing ARINC 664 on its new platforms, and "we’re seeing people pick up on that momentum to place the technology in smaller airplanes like regional jets," said Ben Daniel, avionics general manager in the embedded systems division of GE Fanuc Intelligent Platforms.

"The structure built into AFDX gives aerospace companies the deterministic nature they’re looking for in message fidelity," Daniel said. "We’ve made a bet on AFDX, and we’re seeing some of the big players adopt it. The reality is that we’ve seen an expansion (in the adoption of the technology) in the last year, and not just by the big primes."

The continuing application of 1553 in the face of competition from fiber and Ethernet-based databus solutions provides continuing encouragement to providers of 1553 databus systems, who have responded with what can be called medium-rate throughput systems like Hyper 1553 from Data Device Corp. (DDC), of Bohemia, N.Y., and Multi Rate 1553 from NHI, Ronkonkoma, N.Y.

Prior to the 1970s, data communications on aircraft was point-to-point (box to box). It did what it was supposed to do, but the weight penalty of all those wires connecting each point was enormous. Mil-Std-1553 solved that problem in the 1970s by replacing the wired system with a local area network under which a number of boxes were attached to a single wire bus. Clock rate was an astronomical-for-the-time 1 Mbps, and it’s been pretty much that way until today.

Classic 1553 has been robust and reliable. For added capability, another bus could be easily added to a platform. Lately, though, the many new applications that military and commercial users want to run over the traditional aircraft data communications infrastructure has changed. Sensors generate more data than ever before, with a requisite need to process that information. All of that has led to the development of fiber and Ethernet.

"There’s certainly a movement in those directions for new designs," said Tony Perry, European sales and applications manager for API Nanotronics. "Fiber is a departure for Airbus, but they’re very satisfied with their solution."

Card Flexibility

One of the things that has kept 1553 fresh, besides greater throughput, is new flexibility in the technology that permits the location of multiple 1553 solutions on a single card.

"Maybe they want FPGAs," said Harry Perry, director of engineering for NHI, referring to field programmable gate arrays. "We’re providing transceivers separately from the IP, which is the protocol operation of the design. This is software that can be used in FPGAs so you can have three channels or five channels or eight channels in a single design."

Excalibur Systems this year added a conduction-cooled multifunction 1553 ccVME card with 16 independent channels, double the previous density. Each channel has its own processor. The company planned to introduce a modular PCIe card, based on the PCI Express platform, offering increased throughput over PCI, Sponsler said.

To facilitate the trend toward multiple solutions on a single, commercial-off-the-shelf (COTS) board, a number of manufacturers have created the FMC Alliance to promote the VITA 57 FPGA mezzanine card concept. The VITA 57 FMC standard provides an electro-mechanical standard for I/O mezzanine modules that work closely with FPGA processors in order to optimize the handling and formatting of data.

Members of the FMC Alliance include Altera Corp., of San Jose, Calif.; Alma Technologies, of Pikermi, Greece; Elma Electronic, of Wetzikon, Switzerland; Kontron, of Eching, Germany; National Hybrid; Nolam Embedded Systems, of Créteil France; Praesum Communications, of Petaluma, Calif.; Sital Technology, of Kfar-Saba, Israel; and Xtech, of Randolph, Mass.

"It is an alternative to our existing terminals," Markowitz explained. "It is a software alternative that uses a FPGA instead of a hardware product. It is the software that is equivalent to the software in a terminal, but instead of selling terminals we’re selling the license to the software that lets users migrate to multi-functional 1553 systems that can do a lot of things. Everyone is trying to do more with less, and looking for solutions that will allow them to offer features that they can’t offer today."

It is a trend that is catching the attention of other major providers of databus technology.

"With the installed base and upgrades and issues associated with the proliferation of new protocols we see continued demand in ARINC 429 and 1553," said Daniel of GE Fanuc. "The technology underpinning those trends is the compression of technology through FPGA-based designs with more gates per footprint."

The recent introduction of a number of new ARINC 429 products is indicative of the strong position the technology continues to hold in the industry.

In September, DDC introduced a new multi-I/O 1553/429 Advanced Mezzanine Card (AMC) that provides up to four dual redundant Mil-Std-1553 channels, eight ARINC 429 receive channels, four ARINC 429 transmit channels, six user programmable digital discrete I/Os, two RS-232 Serial I/O channels, two RS-422/485 serial I/O channels, and an IRIG-B time synchronization input.

The product combines multiple protocols on one card to save space, power and weight in a micro-TCA or Advanced Telecommunications Architecture (ATCA) system, DDC said. The company is targeting the new product at flight data recorders, ground vehicles, Navy applications and other embedded systems that require an AMC card.

Excalibur Systems’ "Dragon" flight box is a ruggedized PC104 and PC104+ system appropriate for data acquisition and recording with two 1553 channels, 10 ARINC 429 channels, serial and discrete interfaces. It offers "one of the densest PC104+ cards for avionics utilization," Sponsler said.

The transference of information throughout the airplane without extra hardware or wiring, along with reduced weight and better reliability because of fewer connections, is something aircraft OEMs are always pushing their suppliers to achieve. In the case of databus technology, the supply chain has been able to respond with new standards-based systems that didn’t exist just a few years ago.

"Today’s aircraft have the capability to handle more information without added complexity and weight," said Mark Paul, avionics director of technology for GE Fanuc Embedded Systems, referring to new aircraft equipped with databus technology that complies with the ARINC 664/AFDX standard. "As you leverage commercial-based Ethernet it gives you some lift in terms of particular hardware that can be used. It’s been slow, but over the last year there’s been a multitude of applications for interested parties that weren’t there before for commercial, military and small operators.

"Another advantage is that AFDX is well controlled in an employed environment and things like babbling nodes are well policed as a function of the standard. In test and simulation, you can employ more commercial gear to lower overall test and simulation cost. With the AFDX end systems and common Ethernet switches in a test and sim environment you won’t get all the policing, but you can use commodity hardware."

Germany’s AIM GmbH is another company addressing the testing, simulation and integration of avionics equipment and platforms installing gigabit AFDX Ethernet-based network protocols. This year, the company introduced a four-port AFDX/Ethernet to PCI (-X) card. The APX-GNET card is supplied with either optical IEEE standard 802.3 1000 Base-SX (optical) or 1000 Base-T (electrical) SFP’s (Small Form-Factor Pluggable) and can be configured as four single or two dual redundant ports.

Among other databus methods of interest is deterministic Ethernet-based time-triggered technology. "There are new technology bases where people are modifying technology as 664 did with Ethernet that allowed new technologies to be inserted," Markowitz said.

Avionics Magazine’s Product Focus is a monthly feature that examines some of the latest trends in different market segments of the avionics industry. It does not represent a comprehensive survey of all companies and products in these markets.

Market Moves

Following are some recent developments announced by databus suppliers.

Data Device Corp. (DDC), Bohemia, N.Y., introduced several Mil-Std-1553 and ARINC 429 products in 2008, including a Multi-I/O 1553/429 AMC card. The card provides up to four dual redundant Mil-Std-1553 channels operating in BC, RT, MT or RT/MT modes; eight ARINC 429 receive channels; four ARINC 429 transmit channels; six user programmable Digital Discrete I/Os; two RS-232 Serial I/O channels; two RS-422/485 Serial I/O channels; and an IRIG-B time synchronization input. DDC said it is ideal for use in navy applications, flight data recorders, ground vehicles, and other embedded systems.
The U.S. Air Force awarded a Commercialization Pilot Program (CPP) contract to ITCN, Inc., of Centerville, Ohio, in October. The program involves a $700,000 investment to transition prototype 1553 databus network test equipment, the Bus Characterization and Integrity Toolset (BCIT), into a ruggedized, commercial preproduction design in order to test embedded military systems under rigorous field conditions. The BCIT is a test instrument for troubleshooting cables, diagnosing bus health and monitoring system performance, the company said.
QuickLogic Corp., Sunnyvale, Calif., in April announced a partnership with Sital Technology, Kfar-Saba, Israel, aimed at expanding QuickLogic’s military customer base. The partnership is designed to optimize Sital’s Mil-Std-1553 controller design for QuickLogic’s ViaLink programmable fabric, the companies said. The controller design will become part of QuickLogic’s Proven System Block (PSB) library for military-grade systems using the PolarPro family of programmable platforms.
Sital Technology and API Nanotronic’s National Hybrid released a Mil-Std-1553 communication engine that integrates a 1553 protocol engine, a dual 5-Volt transceiver, memory management, processor interface logic and 4K or 64K of RAM in a 72-pin Plastic Quad Flat Pack package. National Hybrid designed the transceiver and manufactures the device. The system will be known as Octava in Israel and will be called the Aries Series elsewhere, the companies said.
Holt Integrated Circuits, Mission Viejo, Calif., introduced several Mil-Std-1553 and ARINC 429 products in 2008, including HI-3189, an ARINC 429 line driver designed to be a drop-in replacement for obsolete parts. The device allows programming of the high or low-speed ARINC 429 rise and fall time specifications via a digital input, without changing the value of external timing components, the company said. In conjunction with its partners Premier Magnets, Holt Integrated Circuits in July expanded its line of Mil-Std-1553 interface transformers to include a reduced footprint SMD version. The transformers have a package outline of 0.40-inches by 0.40-inches by 0.185-inches and provide all combinations of turn ratio necessary for transformer or direct coupled Mil-Std-1553 data bus applications.