Proactively managing obsolescence with test system architecture

The test equipment life-cycle spectrum has two opposing ends. On one end, test equipment focused toward consumer products often outlives any one of the products that it is charged with testing. On the other end, the aerospace/defense industry demands that test systems work with many types of devices under test (DUTs). Furthermore, the test systems themselves must remain in service and often outlive the technology contained within the system. Long-term sustainment can be challenging unless the system is designed with its life cycle in mind. The design and deployment of a successful test system includes test executive software, instrument drivers, instrumentation platforms, instruments, test code, and a tester configuration. Commonality among test requirements means a universal test architecture must have the correct points of variance for testing individual DUTs. Although test engineers can design for expected points of variability in their test systems, obsolescence events of specific components are often unpredictable at the time of development. When obsolescence events occur, comprehensive test system validation often demands that test engineers spend valuable time redesigning and revalidating the entire system. Forward-looking strategies that mitigate both software and hardware obsolescence can help significantly reduce the costs associated with recertifying test systems. A software strategy based on a commercial off-the-shelf (COTS) test executive software architecture can protect against operating system obsolescence. Hardware abstraction layers (HALs) or measurement abstraction layers (MALs) can help with the inevitable end of life of individual hardware components within the tester. In addition, proactively documenting test system requirements with an industry-standard language, such as ATML, helps to ensure a migration path between tester platforms. Hardware obsolescence is more painful because product life cycles and support are left to the vendors, and test system designers can do little to extend the life of a product or component. The growth of modular instrumentation platforms now allows test engineers to build more maintainable systems with “drop in” instrument replacements over time. What happens when a modern platform does not include legacy instrument functionality or performance? Incorporating virtual instruments significantly reduces recertification time by exposing user-programmable FPGAs that can be programmed to mimic the functionality of obsolete instruments and measurements. For example, digital signal processing (DSP) can be implemented in the FPGA of a software-designed digitizer to mimic the expected frequency response of older instrumentation. This paper discusses techniques for proactively managing obsolescence in any test system architecture and replacing the functionality of obsolete instruments with virtual instruments.