Many times when a branch of the armed forces considers a new weapons system, one of the key aspects to be evaluated is how effectively the potential addition will integrate with existing arsenal. It is, of course, necessary to update equipment to ensure mission readiness in the face of potential enemies developing their own advanced capabilities. However, a weapon's backward compatibility with the existing logistical infrastructure of the military it will serve is just as important as its battlefield performance.

One extreme case that highlights the importance of backward compatibility is the Navy's A-12 Avenger II program. This aircraft was meant to have stealth capabilities and superior performance. However, cost overruns and engineering challenges led to its cancellation in 1991. It could be that the demanding requirements of carrier operations were the ultimate reason for the demise of the A-12 program (as well as the failure to pursue a naval version of the F-22), indicating that the mix of carrier operability and stealth technology presents an extreme technical challenge. Nevertheless, if an aircraft is not backward compatible with existing aircraft carriers, it cannot be a naval fighter. The existence of special versions of the JSF capable of supporting operations at sea, the CV and STVOL variants, reflects this reality.

In this issue of Defense Electronics, the design articles will present three different technologies that do indeed address backward compatibility. XP Power's Martin Brabham will introduce power designers to the use of COTS dc-dc converters in place of MIL-SPEC hybrids. For all but the most extreme applications, COTS can meet or exceed the electrical, mechanical and thermal requirements of power conversion in military systems at lower cost and with greater logistical support than MIL-SPEC units.

National Instruments' Eric Starkloff and Kevin Bisking will show designers how synthetic instruments use generalized, configurable high-performance hardware to replace expensive specialized test instruments. This article includes a specific example for testing software-defined radio systems (systems which, incidentally, use the same configurable-hardware approach to provide backward compatibility as well as new features and levels of performance). This equipment is not only backward compatible with mature testing requirements, but also inherently upgradable for emerging requirements, making it a sound investment.

The third article from Firefly Energy, written by Dan Jurchenko and Kurt Kelley, describes a fundamental breakthrough in lead-acid batteries, referred to as Microcell technology. It replaces the majority of the lead in the grid electrodes of conventional batteries with carbon-graphite foam. This technology increases reliability and performance while maintaining the conventional lead-acid form factor and casing. It also reduces weight and volume, extends cycle life, expands operating-temperature range, and increases energy capacity. Yet, this technology takes advantage of the existing infrastructure for lead-acid batteries. Not surprisingly, it has gained support from the U.S. Army.

In the News section of this issue, I had the pleasure of interviewing Mike Willis of the Georgia Tech Research Institute regarding a recently developed digital crystal video receiver system. This system can serve as a direct replacement for analog crystal video receivers in radar warning receivers aboard fighter aircraft that are more robust and cost effective. As with the other technologies discussed in this issue's design articles, it can also enable more advanced capabilities in the host system, possibly including radar signature analysis for target identification.

As this is being written, Memorial Day, a day that encourages reflection and appreciation for the true cost of freedom, is close at hand. There are limits to backward compatibility, and many of those who are remembered every year on this day used military technology that has long since become obsolete. However, that same technology is also the backdrop for stories of great courage and sacrifice, filled with inspiring examples that will always be forward compatible with the present.