Software Defined Radio – What’s it all about

Software Defined Radio began in the late 70s in the military and continues to evolve today primarily in the defense industry. The Joint Tactical Radio System
(JTRS) is one of several programs continuing the development. The JTR hopes to deploy new radios that use software to change frequency and modulation and support both narrowband voice and broadband data requirements. The Joint Tactical Radio will include software application waveforms with Wideband Networking Waveform (WNW), network services, and the programmable radio set. You can find a more detailed architectural overview here.

Joe Mitola, now with, Mitre coined the term Software Defined Radio in the 90s and began by building them for the military. His definition is used throughout the industry which states,

“Software Defined Radio is a radio that is flexible (programmable) to accommodate various physical layer formats and protocols.”

His book, Software Radio Architecture: Object-Oriented Approaches to Wireless Systems Engineering talks about the roots of the technology and its early days.

One of the challenges in implementing SDR is the need for a fast and flexible architecture. Researchers at Rice propose combining the DSPs and FPGAs to a stream-based architecture to achieve the performance that DSP and FPGAs can’t reach alone. You can see how they implemented the Imagine Media processor from Stanford to test their theory, by clicking
here.

The next step beyond Software Defined Radio is Cognitive Radios. Cognitive Radios go a step further by learning the waveforms and protocols for adapting to the local spectral activity and needs of the user. For example, a cognitive radio could identify empty spectrum to communicate more efficiently. This
EETimes article provides more info.

If you are interested in learning more, you can find a rich set of resources for Software Radio can be found here.

As always, if you are working with Software Defined Radio, I would like to talk with you further. Please contact me at hall.martin@ni.com.

Best regards,
Hall T. Martin