Although the number of custom designs in military and aerospace applications is shrinking, designers still have the need for custom components, boards, and subsystems. They often find the answers to their problems by blending COTS and custom components.
By John Rhea
Acceptance of COTS — short for commercial off-the-shelf equipment — is virtually complete throughout the defense industry. Today, systems designers have to justify using custom components, where only a decade ago they had to justify using off-the-shelf parts.
Still, there remain pockets of military and aerospace applications where COTS, according to its strict definition, simply will not suffice.
To work in today`s world, it is crucial for today`s military, aviation, and space systems engineers to grasp what constitutes COTS design, what constitutes custom design, and to understand the different role of COTS and custom design approaches.
The accepted definition of COTS simply refers to components that are available from manufacturers` catalogs or through distribution channels — regardless of specifications. That which is not COTS, however, involves some level of custom or value-added design.
In today`s COTS world, decision makers are building military and aerospace systems with state-of-the-art technologies derived primarily from the vast commercial electronics industry. It is obvious to most experts that, except in isolated cases, there is no going back to yesterday`s full-custom design approach. Instead, designers are confronting a new paradigm. Where they once relied exclusively on custom components, today they rely on a blend of COTS and custom parts and packaging. Many refer to this new approach, which uses COTS as a foundation, as "value-added COTS."
While the design focus in this environment has shifted toward COTS and away from custom, the tradeoffs involved with COTS-based design have not. Designers still wrestle with the issues of cost (frequently dictated by volume), availability (also volume-dependent), performance, and environmental considerations. As the COTS movement matures, designers are pinpointing the areas where pure COTS comes up short, and where they must blend COTS and custom in the pursuit of value-added COTS.
The primary design tradeoff in this approach is not between ceramic parts and plastic-encapsulated modules (PEMs); both categories can be either COTS or non-COTS. Instead, the central tradeoff is between standard parts available to all would-be buyers and the custom designs that are proprietary to the producers and therefore incorporate intellectual property (IP) rights not available on the open market. In the former, development costs come essentially free to the user; in the latter, the user must bear the costs of non-recurring engineering (NRE) and can recoup some of these costs by retaining the IP rights.
Ray Alderman, executive director of the VME International Trade Association (VITA) in Scottsdale, Ariz., uses three criteria to separate non-COTS designs from COTS designs. Non-COTS designs involve:
- components that typically require what many consider to be excessive NRE costs;
- applications that may endanger human lives — or what he calls "blood on the specs"; and
- applications that are so far removed from commercial applications that they justify custom designs, such as radar and sonar systems.
-Applications such as these continue to defy the attempts of COTS suppliers to muscle into this area. "This is the big wall we can`t get through," Alderman says. "We continue to see COTS rise and soak up the lower-end applications," he adds. Still, Alderman says designer resistance to using COTS even in applications such as radar and sonar "is breaking down."
This trend is continuing as system and subsystem makers scramble to find the best combination of technologies to meet their needs.
If the parts they need, for example, are not available from commercial sources, engineers must commission custom chips from parts vendors or for-hire wafer-fabrication houses. Often the design process involves adding value, capability, and ruggedness to off-the-shelf items with innovative packaging or remanufacturing. At any rate, the days of captive suppliers and vertical integration are over, Alderman concludes. The prize is the intellectual property rights embedded in the products.
The need to start with COTS as a baseline is a fact of life in today`s designs, experts say. "The government doesn`t want to pay non-recurring costs, so we use a lot of COTS and a lot of non-COTS," says Dave Reilly, vice president for engineering at General Dynamics Information Systems in Bloomington, Minn. For space applications, particularly those in low-Earth orbits that require some level of radiation hardening, GD Information Systems engineers use COTS chips such as the PowerPC because of the cost advantage, Reilly notes. How-ever, memory parts still have to be fully radiation hardened.
An example is the new 450-million-instructions-per-second command and data handling space processors based on the commercial PowerPC. GD Information Systems designers are developing this system for a constellation of 30 to 35 communications satellites from Final Analysis Communication Services of Lanham, Md. The constellation, to be known as Little LEO, will serve commercial mobile and fixed-site two-way digital data services applications. Service is to begin in 2001.
In a growing number of designs, engineers have no alternative to COTS as a baseline — even if they wanted to pursue a custom approach. An example is mass storage for military ground and shipboard applications. "COTS disk drives are all there is," Reilly says. The answer is innovative packaging techniques. "We put them into enclosures with shock mounts and vibration dampeners," he says.
In other cases, such as the U.S. Navy`s AN/AYK-14 standard airborne computer — a staple of GD Information Systems predecessor Control Data Corp. — COTS and non-COTS mingle in the mission computer for the F/A-18 E/F jet fighter-bomber. GD engineers must live not only with physical dimensions that the aircraft dictates, but also with the existing environmental- control system. The solution focuses on qualifying the new COTS parts to meet these limitations.
Blending COTS and custom designs, however, has its limits, Reilly says. For example, Reilly says he is wary of PEMs. "In some cases that`s all you can get, but humidity is a big issue," he explains. Also, the special handling that PEMs require increases the cost.
For benign environments that are analogous to commercial aviation, such as the U.S. Air Force`s Airborne Warning and Control System (AWACS) aircraft and the Joint Surveillance Target Attack Radar System (Joint STARS) aircraft, designers can relax the requirements. Reilly describes one of the company`s boxes for Joint STARS as "pure COTS" using a company-designed chassis.
Size is a critical consideration in many systems, particularly spacecraft, in determining whether to use pure COTS or to blend custom aspects with COTS, says Anthony Jordan, product line manager at the Aeroflex UTMC Microelectronic Systems in Colorado Springs, Colo. He says he has found that he can reduce overall system parts count by using custom-designed controllers and signal conditioners around digital signal processors (DSPs) and microprocessors.
That is what UTMC designers have done with the new UT131 embedded controller card that they introduced in March for spacecraft applications that call for converting analog signals into digital representations. By using the gate-array approach and personalizing the applications specific integrated circuit (ASIC) at the last masking and processing step, UTMC engineers were able to reduce the parts count from 40 to 10. This is far from a full-custom design, but Jordan says it can be profitable in prod-uction quantities of as few as 100 units.
This is at the opposite end of the custom-design spectrum, the standard-cell approach, in which the producers start with bare silicon and produce a chip optimized for select applications. However, this requires production runs of at least 50,000 devices to cover the NRE of the mask and processing steps, says Joe Benedetto, principal reliability engineer at UTMC. "If you can`t get the performance any other way, you`ll do it for only five devices," he adds. Somewhere in between the gate arrays and full custom is the use of standard cells from cell libraries to create system-on-a-chip designs, Benedetto adds.
A strong advocate of the value-added COTS approach is Steve Paavola, product manager at Sky Computers Inc. in Chelmsford, Mass. "We adapt a current product to match the requirement, whether it`s custom or semi-custom," he says. Paavola worries that full custom requires high volume to recoup costs, and can lead to schedule slips if design errors take too long to fix. Instead, Sky engineers use off-the-shelf silicon and customize it through field programmable gate arrays (FPGAs) to create a variety of multiprocessor systems.
"FPGAs are wonderful," Paavola says. "We can fix a bug in a matter of hours." Once the initial customer is satisfied, he adds, the systems become catalog items for Sky. For example, the original SkyStation multiprocessors based on old Intel i860 processors have been configured into what he calls a "pizza box form factor" for workstations and then upgraded to medical diagnostic equipment. Sky engineers, who initially used the later SkyPack product line in sonobuoys, also incorporated it into computer-assisted tomography (CAT) scanners, first with 16 i860s and then with as many as 48 SHARC DSPs or 16 PowerPC microprocessors.
Engineers at CSPI in Billerica, Mass., start with COTS components, use them to create custom-designed proprietary boards and backplanes, and then try to sell these products as value-added COTS, says Mike Stern, the CSPI vice president for operations. "We try to sell standard chassis, but sometimes we need customization," Stern notes.
CSPI engineers also use FPGAs and ASICs to add custom value to company designs, using pure COTS for interface, processors, and memory components. "Once you`ve paid for the NRE, the cost of ASICs is low," Stern explains. These costs can run $50,000 per device, but on the board "jelly-bean" standard components that cost from $1 to $4 apiece surround the ASICs.
Myriad Logic officials in Silver Spring, Md., use COTS to expand their military work into commercial applications that operate in extreme temperatures, says Myriad President Richard O`Connell. They re-engineer custom boards by using commercially available industrial-grade components, he says. They looked at upscreening but realized that approach yielded insufficient volume to cover NRE costs. "The DOD COTS initiative has been very beneficial to us," O`Connell says.
Myriad engineers originally developed their primary board offerings for the Northrop Grumman Corp. Electronic Sensors and Systems Division in Baltimore. These boards served as I/O in the Northrop Grumman Common Image Processor. Myriad experts have since re-engineered these boards for use in the oil exploration and medical imaging industries. The military and oilfield applications are similar because they involve remote sensing.
Engineers at the Multichip Products Group of Analog Devices in Greensboro, N.C., derive their value added from finding the right mix of components in their multichip modules, says Bob Scannell, the group`s business development manager. This involves using parts not originally developed with the needs of these users in mind and "pushing the envelope" to achieve a "higher level COTS solution."
Mixed-signal and power components have their own special requirements, Scannell says. Ceramic parts dominate these applications because of user demand. Scannell says he is wary of plastic parts for mixed-signal and power applications because they are extremely sensitive to moisture penetration, and tend to delaminate.
Surface-mount parts with functionality matching mil-spec parts that once appeared on the Defense Department`s Qualified Parts List (QPL) can be designed into customized systems without actual QPL parts, says Ken Warner, sales manager at Technitrol Pulse Components Division, Bristol, Pa.
For a classified space program at Litton Amecom Division in College Park, Md., known as the Instantaneous Frequency Measurement Unit, Pulse engineers are buying capacitors and resistors from commercial sources, doing the burn-in and thermal shock tests on the parts, and then incorporating them into a surface-mounted delay line.
Engineers at VME backplane designer Bustronic Corp. of Fremont, Calif., do 60 to 80 custom board designs a year for the big prime contractors serving the military and government markets, says Fred Hirsch, the company`s general manager.
Although COTS parts can meet most of Bustronic`s needs, company engineers still use custom components for power bus bars and power feed mechanisms, he says. The determining factor is economics, Hirsch says. "This is becoming a more competitive business and the customers are becoming smarter." The company has 20 employees and shipped 30,000 backplanes last year, he says.
Company designers have been moving toward plastic parts with the exception of capacitors, which are still mostly ceramic, Hirsch adds. In previous years Bustronic engineers bought larger numbers of custom components than they do today, particularly connectors. Now, however, they can incorporate extended-temperature-range COTS parts onto boards that meet the MIL-STD 55110 requirement. Earlier this year Bustronic leaders expanded their VME line to include a standard VME64x backplane series and a VME64X extender board. "Because of the need for off-the-shelf racks and form factors, we are sticking with off-the-shelf connectors," Hirsch comments.
Engineers of German board manufacturer Men Mikro Elektronik of Nuremberg, are using ceramic parts sparingly and relying instead on extended-temperature-range commercially available components that they qualify in their own test labs, says marketing manager Barbara Schmitz. Men Mikro designs VME and PCI printed circuit boards.
Schmitz says the extended-temperature-range COTS devices that Men Mikro engineers use have operated successfully to 125 degrees Celsius and met the shock and vibration requirements for demanding applications. Men Mikro boards control torpedo tubes in the French navy and drive cockpit displays in the Eurocopter helicopter. Even at extended temperature ranges company engineers have not had to test all boards since the components have already been qualified, thus reducing costs and delivery times, she says.
Designers at Concurrent Computer Corp. in Fort Lauderdale, Fla., mix and match standard and ruggedized COTS components, says Bob Calzaretta, senior account manager in the company`s Spring Lake, N.J., office. Concurrent engineers use the PowerPC microprocessor, as well as other COTS components, in a line of multiprocessing computers spanning a wide range of military environmental requirements, Calzaretta says. This involves an open-system architecture and a VME 6U form factor for such diverse applications as the Air Force`s Advanced Airborne Command Post, radars on the Navy`s Aegis cruiser, and Army fire control units deployed in the field.
The new `Little Leo` satellite constellation will use a mix of COTS and radiation- hardened chips.
Custom evolving into COTS: The boards developed by Myriad Logic
and General Dynamics Information Systems began life as designs for specific programs and now are offered by their producers for other applications in more benign environments.
Sky Computers` HPC-1 supercomputer relies on FPGAs for its upwardly compatible line of multiprocessors used initially in specialized applications and then made available as catalog items.
The testing challenge of custom components
SAN JOSE, Calif. — Testing represents 10 percent of the cost of electronic systems, and mixing and matching custom and standard components on a board increases the challenge, says Vinod Agarwal, president of LogicVision Inc. of San Jose, Calif.
Agarwal describes a typical board for a spacecraft that would embody applications-specific integrated circuits (ASICs), memory components, and off-the-shelf parts such as microprocessors, controllers, and analog devices. The challenge, he explains, is to find a way to test all the embedded logic interconnected at the board level.
"The most complex parts cause the most problems," he says. "More than half the battle`s won if you can test the ASICs and the memories." ASICs are designed from the ground up and can contain the equivalent of more components than are on a standard board. As a result, LogicVision designers use embedded testing to test them at their operating speed. It is not necessary to use such stringent testing on purely off-the-shelf or analog parts, Agarwal adds.
In the case of a communications satellite program at Hughes Space & Communications in El Segundo, Calif., Hughes engineers had 10 ASICs custom-designed, each on different boards and each designed with embedded memory. They can conduct embedded tests literally "in the field" by warning of incipient failures while the spacecraft is in orbit, Agarwal says. The same testing methods are equally applicable to commercial electronic systems and can be used throughout a product`s life cycle, he says.
Designers insert the embedded test circuits using LogicVision`s proprietary design tools, which generates test programs. By minimizing the need for capital- and labor-intensive external test, company officials say that embedded test shortens time to market and reduces test costs.
In addition, engineers can re-use the embedded test circuitry hierarchically at the board and system levels. For integrated circuits consisting of more than 1 million gates, embedded test requires less than 2 percent silicon overhead, LogicVision officials say. — J.R.