Software radio

A radio software , in English Software Radio operator or Software Defined Radio operator (SDR) , is a radio definite mainly by Logiciel and to a lesser extent by the Matériel.

In the direction reception, the material part is limited to the conversion of the signal high frequency around an Intermediate Frequency (FI) and to its rough digitalization by a Numerical Analogical Converter (CAN).

The treatments which follow can then be realized in a software way: filtering, decimation, demodulation, decoding,… These treatments are carried out using a microprocessor dedicated to the treatment of the signal (DSP, digital signal processor), of a component dedicated to the treatment of the signal (ASIC: Application Specific Integrated Circuit), of a programmable electronics component (FPGA, Field Programmable Spoils Array), or directly on the processor of a traditional PC. That confers a Universalité and a great adaptability on the receiving transmitter/. Indeed, it is enough to change or adapt the Logiciel to function with a system radio different.

In a traditional radio operator system, the emission/reception is ensured by material components (oscillating, filters,…) specific and adapted to the systems for which it is intended. It is not thus often possible to use other systems without changing the material and thus the entirety of the receiver.

The field of the radio S software is under development constant.

Examples of applications

The software radios for example are used in the networks radiomobiles (GSM, UMTS,…) on the level of the basic stations (BTS: Base Transceiver Stations). They have the following advantages:

- possibility simultaneously of emitting (and of receiving) signals in several channels, using a single receiving transmitter/

- performances increased in reception compared to traditional radio technologies

- possibility logiciellement of updating the BTS to support new modulations (example: migration of standard GSM to standard EDGE)

Examples of achievements amateures

Several achievements of software radios today were developed by the community radio operator amateur (see the external bonds)

The simplest achievements use a conversion of frequency generating a signal into squaring (I/Q) numérisable by a simple chart its of stereo PC. Sampling is done typically to 44 Khz, 96 Khz or 192 Khz, authorizing the digital processing by a PC of a complete block of spectrum of width 44 Khz, 96 Khz or 192 Khz respectively.

The most sophisticated achievements use dedicated converters Analogique/Numérique, functioning with more than 100 Méchantillons/s. the signal thus digitized gross is then converted into a numeric signal I/Q with low flow, then transferred by USB or Ethernet towards a PC, which deals with the treatment of the samples (demodulation, calculation of spectrum, etc…). This technique authorizes the digital processing by a PC of a complete block of spectrum of width 2,5 MHz and more.

External bonds

Communications Research Center Canada (CRC) Software Defined Radio operator Research
Finish Software Radio operator Demonstrator
Defined Software Radio operator Forum
Some achievements of Software Radios amateures

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