1. Adapting the USRP as an Underwater Acoustic Modem Paul Ozog, Miriam Leeser, Milica Stojanovic Department of Electrical and Computer Engineering Northeastern University, Boston MA Provide underwater acoustic (UWA) researchers with a low-cost, configurable modem to implement their work → Used to research underwater networks → Lifts constraints imposed by cables

2. The Universal Software Radio Peripheral: www.ettus.com www.gnuradio.org ω ω CF USRP Transducer Cypress FX2 USB Controller Altera Cyclone EP1C12 I0 Q0 USB 2.0... I0 Q0... I0 Q0 Open source hardware/software ADC 12 bit resolution 64 Msps Digital Down Converter Converts to baseband USB Interface Interleaves multiple Rx channels over serial connection

3. The Universal Software Acoustic Peripheral (USAP) USRP/ GNURadio Custom DSP blocks Modified FPGA Functionality Hydrophones USAP/ GNURadio Cost effective Open platform Configurable Software Hardware Acoustic

4. Obtaining Suitable Bandwidth Over USB 2.0 Solution: Define USAP object which maximizes USRP Digital Down Converter's decimation rate to 256 and preforms “by 2” decimation in software, using pass band FIR: Expected underwater acoustic (UWA) bandwidth: ~100kHz FPGA decimation factor: [8,256] USRP() gr_fir_filter_ccf() USAP() RF Bandwidth UWA Bandwidth 250kHz - 8MHz ~100kHz f 256kHz is too much bandwidth for UWA network research