Acknowledgements

1
Rice Atmospheric Information Network (RAIN)
Joe Halbouty, Clay McPheeters, Genaro Picazo, Ed
Rodriguez, Daniel Wu
The Transmitter
Assessment

• Floods in Houston, other cities costly
• Current systems are expensive and
• dont produce data in real-time
• RAIN sensor network robust, real-
• time, inexpensive, non-invasive,
• scalable design
• Designed to measure accurate meteo-
• rological data, predict flooding, early
• warnings for residents, businesses

• Employs binary frequency shift key (FSK)
  transmiss-
• ion 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

• 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 lt 400

System Design Principles
Assembled Transmitter Circuits
Receiver TMS320F2812 DSP

• 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

Transmitter Circuit Schematics
The Receiver

• TI TMS320F2812 DSP real-time calculations
• Rainfall ? scintillations in signal sample _at_ 22
  kHz,
• calculate signal variance to measure rain rate
• Bandpass filter around 1 kHz remove low
  frequency
• turbulence variations, well-defined data
  relationship

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

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

DSP real-time calculated spectrum of -----10 kHz
input square wave
Acknowledgements
Real-time spectra of filtered output on DSP

• Constant K relates laser data to a tipping
  buckets
• data, calibrates computation of laser data
• Spherical domain equation gives rain rate
  directly

• Profs. Young and Baraniuk, our advisors
• Stephen So and Patrick Frantz, for their
  --extensive support with the F2812 board