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Rice Atmospheric Information Network (RAIN) Joe Halbouty, Clay McPheeters, Genaro Picazo, Ed Rodriguez, Daniel Wu Project Motivation The Transmitter Assessment - Floods in Houston, other cities costly - Current systems are expensive and don’t produce data in real-time - RAIN sensor network: robust, realtime, inexpensive, non-invasive, scalable design - Designed to measure accurate meteorological data, predict flooding, early warnings for residents, businesses - Employs binary frequency shift key (FSK) transmission scheme at 9 kHz and 11 kHz; others possible - Measurement and communication in same path - Power supply of 6V battery regulated to 5V - Comparator converts input of 0V or 5V to .8V or 1V - AD654 voltage-to-frequency chip produces FSK bits Assembled Transmitter Circuits System Design & Principles - Network of independent nodes: gather local data, all compiled by central server - Dual laser use for optical detection and communication: low power, overhead vs. radio communication - Equipment cheap, standard: laser-pointer, DSP vs. current RADAR Receiver TMS320F2812 DSP Transmitter Circuit Schematics The Receiver - TI TMS320F2812 DSP: real-time calculations - Rainfall → scintillations in signal: sample @ 22 kHz, calculate signal variance to measure rain rate - Bandpass filter around 1 kHz: remove low frequency turbulence variations, well-defined data relationship System operation block diagram: transmitter and receiver - Each node has transmitter, receiver - Rain disturbs transmitted signal - Received signal hits photodiode, output to DSP for rain rate calculation - Rain data transmitted via network to server access points - Transmitter design is well-suited for data collection and transmission (FSK) - Compact circuits keep node size small - Receiver DSP progress slow, but results are accurate real-time calculations - Processing local data at nodes will mitigate overhead of central processing - Low-power equipment for efficient nodes - Single node cost: probably < $400 DSP real-time calculated spectrum of -----10 kHz input square wave Real-time spectra of filtered output on DSP - Constant K: relates laser data to a tipping bucket’s data, calibrates computation of laser data - Spherical domain equation gives rain rate directly: 2 2 : variance, L : path length K 4L f h f : filter bandwidth, h : rain rate 10 cm x 6 cm 13.5 cm x 7.5 cm Looking Ahead - Use DSP to solve for actual rain rate - Equip DSP with D/A: data transmission - Transmitter control: MSP430, GNOMES - Complete design of independent nodes - Networking: redundant, dense, efficient Acknowledgements - Profs. Young and Baraniuk, our advisors - Stephen So and Patrick Frantz, for their --extensive support with the F2812 board