The Software Defined Radio Team D. J. Love, C.-C. Wang, and J. V. Krogmeier School of Electrical and Computer Engineering Purdue 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: magnetic field sensors Inductive-loops: eddy current sensors

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

Example Signatures from I-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