Software Defined Radio and the GNU Radio Project

Bdale Garbee - HP / Debian

Software Defined Radio is the notion of replacing as much of the signal processing hardware in modern communications systems as possible with software. While the idea is simple, building working systems requires specialized knowledge in computing and communications.

The GNU Radio package separates the heavy-lifting of building signal processing blocks from effort at a higher level of abstraction to connect those blocks in meaningful ways. Understanding of communication systems design is still required, but GNU Radio is making it possible for a broader range of participants to contribute to the development of SDR technology.

The politics of SDR, in particular the challenges posed to and by spectrum regulatory bodies, makes SDR something more people should try to understand. (...)

+ abstract here
+ presentation at the Linux UK 2005 conference, Swansea here


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Further:

+ link to GNU Radio project here

+ Overview:


Eric Blossom | Exploring GNU Radio
Initial version published in Linux Journal, Issue 122, June 2004, as GNU Radio: Tools for Exploring the RF Spectrum.
See here

Abstract: This article provides an overview of the GNU Radio toolkit for building software radios.

... Perhaps most exciting of all is the potential to build decentralized communication systems... These user-owned devices would generate the network...

Software radio is a revolution in radio design due to its ability to create radios that change on the fly, creating new choices for users. At the baseline, software radios can do pretty much anything a traditional radio can do. The exciting part is the flexibility that software provides you. Instead of a bunch of fixed function gadgets, in the next few years we'll see a move to universal communication devices. Imagine a device that can morph into a cell phone and get you connectivity using GPRS, 802.11 Wi-Fi, 802.16 WiMax, a satellite hookup or the emerging standard of the day. You could determine your location using GPS, GLONASS or both.

Perhaps most exciting of all is the potential to build decentralized communication systems. If you look at today's systems, the vast majority are infrastructure-based. Broadcast radio and TV provide a one-way channel, are tightly regulated and the content is controlled by a handful of organizations. Cell phones are a great convenience, but the features your phone supports are determined by the operator's interests, not yours.

A centralized system limits the rate of innovation. We could take some lessons from the Internet and push the smarts out to the edges. Instead of cell phones being second-class citizens, usable only if infrastructure is in place and limited to the capabilities determined worthwhile by the operator, we could build smarter devices. These user-owned devices would generate the network. They'd create a mesh among themselves, negotiate for backhaul and be free to evolve new solutions, features and applications.

(...)

Politics

Every revolution has its political issues. Free software for building radios is troublesome to some people. In the US, we've run into opposition from the Motion Picture Association of America and its attempt with the Broadcast Flag to restrict the kinds of receivers that can be built for over-the-air digital TV.

The US Federal Communications Commission has issued a Notice of Proposed Rule Making (NPRM) concerning Cognitive Radio Technologies and Software Defined Radios. Several troublesome issues are raised in the NPRM, including restricting the sale of high-speed digital-to-analog converters, requirements for digital signatures or similar methods to keep unauthorized software out of software radio hardware and new restrictions on radios built for the amateur radio market.