Software Defined Radio (SDR) was first conceptualized – as many radio advances have been – for its military applications. Beginning in 1970, The Department of Defense, Defense Advanced Research Projects Agency, and TRW, Inc. – the lead aerospace contractor of the first intercontinental ballistic missile program and builder of US spacecraft – all played a part in the development of the first software radio receiver.

Forty years later, the computing capabilities needed to process radio signals are available to anyone with a personal computer.  Since all signal processing is done by software which can automatically recognize modulation modes, ideas like AM and FM radio become obsolete. Where once many radios were needed to transcribe the breadth of the RF landscape, now a software receiver allow a listener to “tune in” to any of the frequencies an antenna itself receives.

SDR software also provides bit-rate analysis of the radio signal its antenna receives, allowing for a visual map of the signal landscape.  The visual signature of active broadcast signal is referred to as a ‘waterfall.’

The WebSDR project is a community of stations around the globe that provide access to their software receivers via the World Wide Web.This edition of Special Collections is a live survey of radio from all over the world, being received all over the world, and tuned into right here in Los Angeles.