1. Radio Acoustic Sounding System Preliminary Design Review by Elisabeth Bobrow, Edward Breen, Wisnel Lorzeille, and Daniel Oren

2. Outline  Background  RASS  Project Specifications  Preliminary Design  Proposed MDR Prototype Specifications

3. Background  Variety of vertical air temperature measuring methods –Towers, Tethered balloons, RASS  RASS - cost effective, real-time measurements, mobile

4. RASS  Three main aspects –Transmits acoustic pulses vertically into the air –Uses CW RADAR to measure the Doppler frequency shift of the pulse –Processes these measurement to calculate virtual temperature at various heights

5. Project Specifications  Two CW RADAR antennas needed –One transmitting, one receiving  CW RADAR –Mixer, local oscillator, band pass filter, power amplifier

6. Project Specifications continued…  SODAR –Transmits ~2kHz acoustic pulses vertically at even intervals

7. Project Specifications continued…  Signal Processing –Analog output signal from RADAR converted to digital signal with an A/D Converter –Computer Program  Inputs digital signal and measures Doppler shift of signal from original acoustic pulse  Uses Doppler shift to calculate speed of sound at different heights  Determines virtual temperature from calculated speed of sound

8. Preliminary Design  Two antennas and SODAR are already available  CW RADAR Design –Research required power specifications, implement specifications  Signal Processing Design –Use PC Soundcard for A/D conversion –Write a program using MATLAB on a LINUX based operating system  Use data windowing to distinguish signal’s various frequencies  Plot temperature calculations over time with respect to altitude

9. Proposed MDR Prototype Specification  Design data processing program  Write program in MATLAB  Test program with synthesized signals  Become familiar with existing SODAR system