Initiated some time in the mid-nineties, the United States military is playing a pioneering role in the development of software-defined radio or SDR. Recognizing early the potential of SDR, the Department of Defense (DoD) has established the Joint Tactical Radio System Joint Program Office (JTRS JPO) to achieve that goal. The major thrust of the JTRS effort is a software architecture called the software communications architecture (SCA). With the ability to process multiband waveforms and reconfigure architectures in real time, SDR promises to enable wireless devices to break away from traditional predefined functions and capabilities. Thus, new features can be implemented in real time using software with the power to upgrade the radio with new modulation schemes, protocol standards, and frequency bands in real time.

Consequently, the military has committed billions of dollars to replace hundred of thousands of traditional radios now deployed, with SDRs. According to one analyst, it has become the largest purchaser of software-defined radio (SDR) equipment with shipments to the U.S. military expected to top $1.7 billion by 2007.

Many NATO allies have signed agreements to apply the SCA in their future acquisitions, and the military expects the advances in SCA will also with time trickle down into all sectors of consumer and commercial communications applications. And, the recent leap in DSP processing capability as cost and power consumption climbs down, as well as a surge in density of lower-priced FPGAs, are paving the way for commercial deployment of software-intensive radio.

In fact, for the commercial deployment of software radio, SDR Forum, a non-profit industry organization, is playing an active role in garnering international support and generating standards for expediting its deployment in the consumer world. Wireless OEMs and service providers who see the benefits of deploying base stations and handsets that can quickly switch between myriad configurations and process multiple, multimode waveforms and protocols in a single unit, are rapidly moving in that direction. In reality, some have already taken that step.

To keep the readers abreast of recent developments on the JTRS SDR front, RF Design's Defense Electronics supplement presents a report on this subject written by contributing editor Steve Grossman. Titled “Software-defined radio poses major challenges for hardware and software developers,” the report explores the SDR food chain, as well as the clusters created by the JTRS program to achieve the goals on time.

This issue of Defense Electronics also presents two more articles. “Comparing alternative system architectures for spectrum monitoring” by Chris DeSalvo of Agilent Technologies discloses an ideal system architecture for spectrum monitoring that offers the best ability to identify unknown, short-duration signals with minimum operator attendance. Commercial companies and aerospace/defense contractors are increasingly being requested to monitor wireless signals for security and RF emitter compliance. To enable engineers and designers who are monitoring the spectrum to select the right tool for this application, the author discusses an ideal spectrum monitoring architecture that has been considered in the design of the company's new family of signal-monitoring solutions. This instrument offers wide bandwidth, high-speed search and high resolution to provide an optimum tool to hunt unknown wireless emitters.

XP Power's Martin Brabham, industry director for avionics and aerospace, shows how commercial off-the-shelf (COTS) converters can serve as the basis for military power supplies. While the adaptation of COTS parts is an attractive option, it must provide the overall system performance and reliability, and meet the requirements of the appropriate Mil standards. Hence, this article examines special demands made upon military power supplies and cautions designers that to achieve the end results the key industry standards and specs must be fully understood. To demonstrate the capability, the author presents a working example of a factory configurable COTS dc-dc converter designed for a military system.