Several key trends in military avionics systems

Application of COTS Technology

　　自1976年以来，集成电路的销售量由于它们在计算机、电信设备和电子消费品中应用的增多而增加了40倍。这些集成电路的绝大多数（98%）是塑料封装的微电路（PEM）。PEM首先是在60年代引入的，由于它们的低成本、小尺寸和轻重量而得到广泛应用。随着它们的应用及可靠性的增加，导致它们也用在航空电子、汽车和其他长寿命的设备中。在这同一个时期，集成电路在航空电子设备中的应用保持平稳，引起其市场份额从17%跌到不到1%，使军事部门再也不能影响电子器件的发展。军用级部件市场的萎缩以及要对它们进行筛选以满足MIL-STD-883所需的费用已导致许多大制造商，如摩托罗拉、英特尔和飞利浦关闭了它们的军用电子元件生产线。这显著减少了密封封装的军用规范部件的供应量，特别是最新的和技术上最先进的集成电路紧缺，迫使防务工业考虑采用商业技术的PEM部件。美国国防部已于1994年制订政策，鼓励采用最好的商业部件，以便在军用设备中早日使用经济上负担得起的前沿电子技术产品。

　　The U.S. Department of Defense defines COTS (commercia-l of-the-shelf) as products sold on the market, appearing in the manufacturer's product catalog at a certain price, and available to any company or individual for use directly from the manufacturer or through the manufacturer's sales network. COTS devices have standard part numbers and technical specifications that describe their mechanical, electrical, and environmental properties and limits. COTS products can be divided into categories such as consumer/industrial, military, and aerospace. In PEM, semiconductor chips are encapsulated in a housing using molded plastic technology.

　　尽管PEM具有显著的优点（如新产品，性能好，投放市场的时间短和首批成本低），它们也有一些缺点，如密封性差，抗热循环和冲击的性能差及较小的工作温度范围。制造工艺的变化，甚至制造商和批量的变化，可导致其性能变化越出规定的性能数据。

　　Designers of future fighter aircraft are struggling to cope with the problem of avionics obsolescence. This problem is exacerbated by the increase in development and production times caused by reduced defense budgets and a shrinking military aircraft market. In military avionics systems, the use of civilian 0 open 0 system hardware and software is seen as an important measure to deal with the increasing obsolescence of electronic components. If COTS technology is used, avionics products will no longer be static, and their processor chips will be improved every 18 months.

　　In avionics and computers, commercial off-the-shelf (COTS) technology is already in great demand. Processor improvement projects for US military aircraft alone include: COTS technology improvements to the AN/AYK-14 mission computers for the F-14 and F/A-18, a new modular mission computer (MMC) for the F-16, an M372 general purpose processing fire control computer for other F-16s, a new air data processor for the F-15 and a new IBM CP-1075C VH-SIC central computer, and a new GEC-Marconi digital flight control system for the F-14.

　　The U.S. Marine Corps has taken the lead in the use of COTS technology in avionics by preparing to replace the mission computer in the AV-8B with a civilian processor in its Open Systems Civilian Avionics Requirements (OSCAR) program. McDonnell Douglas (now acquired by Boeing) is the prime contractor for the OSCAR program, and its subcontractor CDI is developing a replacement computer for the AYK-14 mission computer in the AV-8B using a PowerPC civilian processor. The development model of the new computer is scheduled to be delivered and tested in the laboratory in early March 1997, and production will begin before the end of 1997, while improvements to the AV-8B will begin in early 1998. The performance of the civilian processor will be two orders of magnitude higher than that of the AYK-14. The U.S. Navy is also looking for a civilian processor to replace the AYK-14 used on the F-18.

　　The OSCAR improvement program will use common modules with commercial standard interfaces (VME backplane and POSIX-compliant operating system), and initial operational capability is scheduled for 2001. Some OSCAR hardware and software will be used in the F-15's new Advanced Display Core Processor (ADCP). It will be integrated with the F-15E's Multi-Purpose Display Processor (MDPD) and VHSIC in an electronics box, and there will be some differences in the assembly used on the F-15C/D.

　　Engineers at Northrop Grumman are modifying the avionics of the U.S. Air Force's E-8C aircraft to accommodate an increased number of COTS components. Over the past three years, the E-8C's avionics have evolved from using specialized technologies such as DEC's VAX computers and International Devices' programmable signal processors to using open system components such as DEC's Alpha microprocessors, VME backplane data buses, and FDDI (Fiber Distributed Data Interface). Further COTS technology adoption may include the Windows NT operating system, Analog Devices' 21060 SHARC digital signal processors, and the industry-standard Raceway high-speed microprocessor interconnect invented by Mercury Computer Systems.

　　F-22 developers are already dealing with the problem of electronic obsolescence in the F-22, which may not be operational until after 2004, although the aircraft will not enter U.S. Air Force service before 2004. The Lockheed Martin/Boeing group has compiled a catalog of more than 400 parts that will probably no longer be produced by the time the F-22 enters service, in order to address the problem by purchasing parts production lines and inserting new technologies.

　　Lockheed Martin/Boeing has developed a development plan for improving the F-22's CIP, which is to introduce civilian technology to replace discontinued parts and take advantage of the rapid development of civilian avionics to improve performance. The first step, called CIP 2000, will increase storage capacity and reliability while reducing weight and cost. CIP2000 will retain the existing 1960 processor, but will introduce an open system data bus and 3-volt power supply to allow the later adoption of civilian processors. CIP 2000 will be replaced by CIP 2005, which is simply achieved by replacing the plug-in module in the F-22's CIP rack.

　　The JSF is the culmination of the military's move to COTS-based avionics. The four main goals for the JSF avionics are affordability, performance, modifiability, and reusability. JSF program managers seek to reverse the trend of avionics costs rising as a percentage of the total aircraft cost, from 12% for the F-4 to 30% for the F-18. The JSF avionics architecture will use COTS technology to the greatest extent possible in all areas, including processing and networking. The primary design goal of this architecture is to reduce costs, and open system standards for networks, operating systems, and application program interfaces will be used to increase the portability and extensibility of application software and certain hardware for use in other aircraft. The primary purpose of using COTS and open system standards is to increase the life of the software, making the system immune to hardware obsolescence and easier to improve. Using this technology allows decisions about how to implement processors and networks to be made later in the development cycle, allowing for greater use of the latest technology and reducing life cycle development costs.

　　Lockheed Martin claims it has a breakthrough that will help the U.S. Air Force deal with electronic obsolescence in the F-22 and other military aircraft. Digital components may have a commercial lifespan of only 18 months, while the weapon systems that use them have a lifespan of several decades. Obsolescence increases system operating and support costs by about two-thirds of the total lifecycle investment. Lockheed Martin's technology innovation uses coordinated tools and electronic specifications to first replace obsolete airborne printed circuit components with replicas, which the company estimates will reduce maintenance costs by 10% to 15% in the next one to two years. This approach of redesigning obsolete electronic devices using modeling and simulation techniques can be used not only for the F-22, but also for the JSF. The process used to develop the prototype is based on VHSIC hardware description language (VHDL) models. After the prototype is developed to replace the obsolete printed circuit board, it is tested for compliance against the original obsolete printed circuit board in a virtual development environment using commercial software and hardware. In this simulation environment, the redesign of obsolete hardware will mainly use modern component technology. Since the design is done according to electronic specifications, the cost of redesign can be greatly saved.

　　The advantage of the copy technology is that the embedded software and support equipment of the redesigned electronic device can remain unchanged, so there is no need to redevelop the software and support equipment, which saves costs. The U.S. Air Force and Lockheed Martin have signed a VHDL design environment (VDELE) for traditional electronic devices. VDELE overcomes the obsolescence problem by using current technology.

　　Lockheed Martin has used VHDL to rigorously describe the appearance, installation and function of a discontinued circuit board in the F-16 Store Management System (SMS), and then replicated it for verification.