Electronic Design

Make Your Own Software-Defined Radio

Designing a software-defined radio (SDR) just got easier. With interest in multiprotocol radios growing in a host of applications, your next design could very well be an SDR. Some of the next-generation radios requiring an SDR architecture include military radios, public safety radios, commercial radios, and radio-frequency identification (RFID) readers.

The bulk of the design is in the software, but the hardware is still a challenge. Engineers can spend six months or more just pulling together all the hardware needed to make a radio prototype before writing any code.

Texas Instruments Small Form Factor Software-Defined Radio (SFF-SDR) Development Platform should help drive down development time and costs while providing a convenient platform for testing a variety of options and alternatives (see the figure). It consists of three pc boards that divide the radio into RF, IF, and baseband (BB) sections.

The top RF section s two half-duplex radios operate in the 360- to 960-MHz range, which is ideal for designing some of the new public safety radios in the forthcoming 700-MHz bands. Bandwidths of 5 MHz or 20 MHz are selectable.

The middle IF section contains the digital down/upconversion and data conversion. The analog-to-digital converter (ADC) section s two TI ADS5500 ADCs provide 125 Msamples/s with 14-bit resolution. The digital-to-analog converter (DAC) section uses a DAC5687 with dual 500-Msample/s DACs.

The bottom BB section uses TI s TMS320DM6446 system-on-a-chip, which contains TI s TMS320CC64x 600-MHz DSP plus a 300-MHz ARM926EJ-S general-purpose processor. This chip comes with a full set of peripherals necessary for SDR, including serial ports, USB, Ethernet, and connections for DDR2 and NAND flash memory. It features a fully programmable Xilinx Virtex-4 SX-35 FPGA. And, it includes five dc-dc converters and a TI MSP430 MCU for power management.

THIRD-PARTY SUPPORT
The available software includes Green Hills Integrity real-time operating system, which runs on the ARM processor. Objective Inter-face Systems (OIS) is furnishing the Object Request Broker (ORB) middle-ware for the ARM9, DSP, and FPGA for the Software Communications Architecture (SCA) version of the platform. The ORB middleware substantially reduces development complexity and enables algorithm code portability.

The Communications Research Centre of Canada (CRC) supplies the Software Communications Architecture (SCA) core framework (version 2.2), which enables the flexible implementation of different waveforms and protocols in military radios. The platform works with the Simulink model-based design tool.

Designers have the option to use C/HDL or Matlab Simulink to test proof-of-concept designs and then optimize the architecture for cost and power. Lyrtech developed the hardware for the platform and integrated all of the software components of the kit. Lyrtech also will supply support for the system.

The SFF-SDR kit s Power Measurement application programming interface (API) lets developers track the real-world power consumption of the digital baseband unit precisely while algorithm functions are being executed. Traditional power measurement techniques require external measurement of power consumption, which offers rough estimates at best.

This kit provides five different API power measurement functions so engineers can see exactly how much power each section of the radio consumes during operation. With this capability, users can optimize their designs for minimum power consumption in a given application. Given that most SDRs are very power hungry but also battery powered, this feature is a must-have tool.

This SDR hardware/software co-development environment may be just the thing for you. It gives you the RF front-end, analog-to-digital and digital-to-analog converter, DSP, and FPGA all in one integrated system that lets you optimize each for cost and power consumption.

PRICING
Without the SCA core and ORB, the SFF-SDR kit costs $9900. It s available from TI distributors. The BB board alone costs $2900. Lyrtech offers an enhanced SCA version with licensed copies of the complete software suite, SCA framework, and ORB middleware. TI expects considerable third-party support, making it an even better SDR design tool.

Texas Instruments Inc.
www.ti.com/SDRpr
Lyrtech
www.lyrtech.com

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