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Introduction

As adopted by the Forum, the term software defined radios (SDRs) is used to describe radios that provide software control of a variety of modulation techniques, wide-band or narrow-band operation, communications security functions (such as hopping), and waveform requirements of current and evolving standards over a broad frequency range. The frequency bands covered may still be constrained at the front-end requiring a switch in the antenna system.

SDR is an enabling technology applicable across a wide range of areas within the wireless industry that provides efficient and comparatively inexpensive solutions to several constraints posed in current systems. For example, SDR-enabled user devices and network equipment can be dynamically programmed in software to reconfigure their characteristics for better performance, richer feature sets, advanced new services that provide choices to the end-user and new revenue streams for the service provider. SDR is uniquely suited to address the common requirements for communications in the military, civil and commercial sectors.

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What is a Software Defined Radio?

Joe Mitoloa says, "A software radio is a radio whose channel modulation waveforms are defined in software. That is, waveforms are generated as sampled digital signals, converted from digital to analog via a wideband DAC and then possibly upconverted from IF to RF. The receiver, similarly, employs a wideband Analog to Digital Converter (ADC) that captures all of the channels of the software radio node. The receiver then extracts, downconverts and demodulates the channel waveform using software on a general purpose processor." [1]

For our purposes, on the receive side, the idea is to get a wide band ADC as close to the antenna as is convenient, get the samples into something we can program, and then grind on them in software.

Can you give me an example?