The Software Defined Radio Team

D. J. Love, C.-C. Wang, and J. V. KrogmeierSchool of Electrical and Computer EngineeringPurdue University, West Lafayette

January 12, 2011

Software-Defined Radio

Ideal SDR• Connect Antenna to an ADC/DAC

• Sampling frequency limitation in RF• Dynamic range limitation

Practical SDR• Tunable RF Front-end implemented in

hardware• All digital signal processing in software

VIP has two SDR platforms• Ettus Research, LLC + GNU Radio• Rice WARP + Matlab

GNU Radio / USRP Hardware

GNU Radio• Open source software• Provides APIs for flexible PHY and MAC

support• Based on C++/Python programming

Universal Software Radio Peripheral (USRP) by Ettus• Designed to work with GNU Radio• Combination of

Various RF front-ends daughter boards (0-100MHz, 400MHz, 900MHz, 2.4GHZ)

ADC / DAC with data rates up to 64 MSample/sec

All DSP functions in software on general-purpose CPU (PC)

Spring 2011: Four Possible SDR Projects

Power Line Communications (PLC) Interface and SDR Software for MIMO PLC Channel Sounding

FM Transmitter for iPod Using Radio Broadcast Data System (RBDS) to Display Playlist Information

Software Defined FM Receiver for Inductive and Magnetic Vehicle Detectors

Spectrum Sensing and Modulation Classification for Cognitive Radio

Power Line Communications (PLC) Interface and SDR Software for MIMO PLC Channel Sounding

FM Transmitter for iPod Using Radio Broadcast Data System (RBDS) to Display Playlist Information

Software Defined FM Receiver for Inductive and Magnetic Vehicle Detectors

Micro-loops: magneticfield sensors

Inductive-loops: eddycurrent sensors

Micro-Loops and Inductive Loops Appear as Variable L: Measured as Change in Oscillator Frequency

Example Signatures fromI-70 W Near Indy Airport

SDR FM Demodulator for Loop / Micro-loop Signature Logger

Available Hardware is Inadequate for Research• Uses proprietary interface and unknown signature

demodulation algorithms• Very limited ability to change “carrier” frequency• Relatively low sensitivity• Not programmable

Desired capability• Experiment with different FM demodulation algorithms

in order to improve sensitivity• Explore classical FM bandwidth vs. demodulated SNR

tradeoff• Use improved receiver sensitivity to reduce the required

aperture size in inductive loop sensors – lower power and more detailed signatures

• Address self-interference issues that are common in current systems