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T he 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
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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