Vanu and Software Defined Radio Techniques
I found their backgrounder on SDR pretty interesting. In their introduction whitepaper which is only five pages long they layout the basics of how SDR works.
Software Defined Radio goes back many years to the 1980s when cellular base stations were first developed. Through the 90’s the military entered the field and only recently did SDR become commercially viable.
A dual-mode cell phone is the simplest example of SDR which has two radios and uses software to switch between the two. The next level of SDR combines ASICs, DSPs, and FPGAs to achieve performance. Unfortunately, software for those systems must be rewritten to accommodate new generations of chips. The highest level of SDR is one in which software abstracts away from the hardware implementing the signal processing in the software and providing reuse of the software as new generations of chips are applied. In this article Vanu outlines the three levels.
John Chapin wrote a paper on the Vanu Radio Architecture which outlines the difference between Vanu’s approach and the traditional software defined radio approach. Vanu’s approach is to use DSPs and FPGAs to implement the waveforms, but in high-level code running on a POSIX operating system which allows for porting the code to new processors when they become available. Portability is their key advantage.
Next week we’ll meet with John Chapin to hear his perspective on the SDR challenges and issues.