Software-defined Radio

Software-defined radio (SDR) uses software that runs on a microprocessor or CPU to perform many of the basic functions of the receiver. It is possible to reconfigure and use the software on many different processor platforms and for many different functions. SDR technology has been evaluated for a long time and has advanced significantly in recent years. Advances in hardware mean substantially improved processor performance and reduced costs.

Today, software-defined radios are seen in everything from high-end radio communications equipment to simple USB plug-in modules that are available at very low cost.
SDR technology provides significant advantages over traditional hardware based radio designs. Using the power of digital processing, SDR is used in many different applications and areas.

The basic concept of SDR is that the radio can be completely reconfigured or redefined by the software. In an ideal world, the incoming signal would be immediately converted to a digital format and then processed completely digitally. The radio can be totally reconfigured for a new application and standards, simply by changing the software. Updates can be made to keep up with new modulation formats, new applications, etc. It also means that a common hardware platform can be used across a variety of products and applications, thereby reducing costs while maintaining or improving performance.

There are many definitions of software-defined radio. For example, the SDR Forum has defined the two main types of radios containing software as follows:

• Software-controlled Radio: Radio in which some or all of the physical layer functions are software controlled. This type of radio only uses software to provide control of the various functions that are fixed within the radio and for the hardware.
   
• Software-defined Radio: Radio in which some or all of the physical layer functions are software defined. The software is used to determine the specifications and functions of the radio. If the software within the radio is changed, its performance and function may change.

With our long history with the automotive market, particularly the car radio market, this new SDR solution offers reduced hardware cost overhead for many different platforms, with an extremely low SoC processing resource usage for many Terrestrial Digital Radio Broadcasting options like DAB/DAB+, CDR China, DMR/DRM+, HDR USA, T-DMB Korea and ISDB-Tsb Japan.

The solution is the highest performing and offers the fastest acquisition and reacquisition time.

Another definition is that SDR has a generic hardware platform on which software runs to provide functions including modulation and demodulation, filtering (including bandwidth changes), and other functions such as frequency selection and, if required, frequency hopping. By reconfiguring or changing the software, the performance of the radio is changed.

To achieve this reconfiguration, the software-defined radio technology uses software modules that run on a generic hardware platform consisting of digital signal processing (DSP) processors as well as general-purpose processors to implement the radio functions to transmit and receive signals.

In an ideal world, the signal at the final frequency and at the correct level would emanate, the signal from the antenna would be directly converted to digital, and all the processing would be undertaken by the software. In this scenario, no limitations would be introduced by the hardware.