AB9IL - Software Defined Radio
Use panoramic displays with point-and-click tuning to find your next DX catch!
Something very exciting is transforming radio. It is transforming how we communicate throughout the spectrum, from VLF to she shortest microwaves. Instead of using equipment specialized for specific modes, with their inherent limitations, radio designs are emerging that do most of the work in the digital realm. In essence, hardware captures huge chunks of spectrum, digitizes it, and passes it to a digital processing core. The DSP then carries out functions of tuning, filtering, amplification, noise reduction, and demodulation. Multiple operators can use multiple virtual transceivers.
SOFTWARE DEFINITION REPRESENTS A QUANTUM LEAP IN CAPABILITIES! Here is an example; a mere tip of the iceberg:
The Web Controlled SDR at the University of Twente.
Before reading more, point-and-click on that SDR for a while, and apreciate that each change of mode, bandwidth, and frequency was once a carefully orchestrated dance of capacitors, crystals, inductors, and resistors. Excellent performance was difficult to achieve and maintain. In the digital realm, these dances are done in less time than it takes for the sound waves to leave your headphones and reach your eardrums! Now, have a look at the RF components of that receiver:
Imagine a team of operators, scattered in different locations all connecting to one "antenna server" at another location...all using independent transcievers defined by software and limited only by the computing power of their combined equipment. The team could operate in any part of the spectrum, in any mode, using any bandwidth, apply any noise reduction, etc etc etc. Multiple teams could form the ultimate monitoring or emergency communications network. A station could be as simple as a laptop, proper software, and an internet connection...
Amateur radio is already seeing quite a lot of innovation as shown in projects like the Quicksilver and Softrock SDRs. News organizations such as the BBC are moving to SDRs for their monitoring. Even military SDR applications are being implemented (i.e. PAVE PAWS radar). In this digitized world of radio, I find the performance already impressive. Listen to the WebSDR linked above, and note the stable, clean, and sensitive it is. And it started as hardware built "dead bug" style on a piece of copper clad PC board!! Are you impressed? Now, get thee not to a nunnery, but to the gatherings of creative people building the next generation of radio.
Here at AB9IL, I plan to post more SDR information as hardware and software are put into use here...I intend to use a Linux based system using a simple Quadrature Sampling Detector and Linrad for starters. Linrad is developing into a prime program for weak-signal work. It is flexible and based on some truly slick programming from the community of software defined radio operators. It looks good too:
Stay tuned for the latest in software defined radio developments!