AVAPS II DROPSONDE Overview April 28th 2009 AVAPS Users Group Meeting Terry Hock

NCAR/EOL Dropsonde Team Kate Young Dean Lauritsen LauraTudor June Wang Terry Hock Nick Potts Charlie Martin Chip Owens Clayton Arendt Hal Cole Mary Hansen © 2009 Copyright University Corporation for Atmospheric Research 2

AVAPS II Functionality Sensors Pressure, Temperature, Humidity Vaisala RSS-921 PTU module (Standard part) Pressure sensor – no change from RD-93 Humidity sensors – no change from RF-93 Temperature sensor – new fast response sensor Winds and Position via GPS receiver U-Blox TIM-5H receiver, latest generation from u-Blox (RD-93 used TIM-LF, TIM-4P) Date Rate PTU 2 Hz Data (0.5sec) Position 2 Hz (0.5 sec) Winds 4 Hz (0.25 sec) © 2009 Copyright University Corporation for Atmospheric Research

AVAPS II Size Sonde mass: Fall Rate 323 grams, ~18% less weight (RD-93 395g) Fall Rate ~10.5 m/s at sea surface ( ~11.5 m/s RD-93) Same size parachute as RD-93 Same case size 2.75” x 16” as RD-93 Same sensor and parachute bulkheads © 2009 Copyright University Corporation for Atmospheric Research

AVAPS II Operations Pre-Flight Umbilical cable Set 400MHz transmitter frequency Umbilcal cable has no other required functions RD-93 required upload of PTH sensor coefficients to PC If sonde frequency is preset, there is no need for use of umbilical cable Sonde has a 2nd serial port through umbilical cable to u-Blox GPS receiver. Optional - Upload GPS ephemeris data for quick satellite acquisition, still under investigation for dropsonde use in an aircraft, all ground tests are very promising. © 2009 Copyright University Corporation for Atmospheric Research

AVAPS II Sonde Design 3 lithium batteries, nominal 8 volts, Minimum voltage required is 6 volts 2 microcontrollers PIC18F….FLASH easily to update firmware Vaisala PIC measure PTU sensor frequencies Calculate Pressure, Humidity, Temperature in sonde Main Sonde PIC Controls Vaisala PIC Controls GPS receiver Controls 400 MHz transmitter Creates telemetry data message Interface configuration during manufacturing U-Blox TIM-5H GPS receiver 4 Hz update rate 50-channel engine with over 1 million correlators Improved sensitivity, -160dBm “Improved GPS satellite acquisition time” L1 only receiver FLASH EEPROM easy to upgrade firmware Sensor expansion capability for other sensors, i.e. ozone, electric field strength. . . © 2009 Copyright University Corporation for Atmospheric Research

AVAPS II Sonde Design (cont) 400 MHz Transmitter uses a RF ASIC Fractional Synthesizer for fine frequency resolution Spectral purity same as RD-93 RF Bandwidth ~20kHz Operates in 400-406 MHz Meteorological band Eliminated manual adjustments during manufacturing, cost reduction (RD-93 had 2 required adjustments) Same antenna design New Modulation Scheme Frequency Shift Keying (FSK) modulation (RD-93 had 2 modulation signals) 2400 Baud data rate Manchester encoding PTU and GPS data all embedded in same data stream Telemetry errors should be similar between PTU and GPS Electronic Components are all “ROHS” AVAPS II Dropsonde 170 electronic parts (~20% fewer electronic parts) RD-93 Dropsonde 214 electronic parts © 2009 Copyright University Corporation for Atmospheric Research

Launch Detect Mechanism Dropsonde Goals for new system Reliable Low Cost Simple to implement Optical Light beam Electronics in parachute compartment Packed parachute block beam Low cost No Mechanical parts RD-93 Sonde is a shorting pin attached to the parachute riser line via a string Drop tests have shown 100% reliability. Parachute Chamber CDS Photo Detector White LED transmitter Electronics GPS Antenna © 2009 Copyright University Corporation for Atmospheric Research

Sonde Comparison RD-93 & AVAPS II Sonde AVAPS II RD93 AVAPS II RD93 © 2009 Copyright University Corporation for Atmospheric Research

Summary of Cost reductions Single PCB assembly vs 2 PCB assemblies No manual tuning adjustments required of transmitter Simplified launch detector, removal of shorting pin/string Removal of bunchee cord assembly in parachute riser line Reduction of electronic parts by 20% 2 layer PCB vs 4 layer PCB Next generation of production test software uses bar code reader to simplify process Reduced the number of cells in battery pack from 6-cells to 3-cells cost, weight, safety, shipping © 2009 Copyright University Corporation for Atmospheric Research

Summary Performance Changes Faster response temperature sensor Improved telemetry for GPS wind data Improved reliability of launch detect Possibility of no GPS re-radiation required (pre loading GPS ephemeris data) 4 Hz (0.25 sec) GPS Wind Data !! System easily adapted to adding other sensors © 2009 Copyright University Corporation for Atmospheric Research

AVAPS II Development Roles NCAR Development; New Dropsonde, Telemetry chassis modifications and AVAPS Software, production of prototypes Dropsonde and telemetry cards. Drawing package Support Dropsonde production Data analysis NOAA/AOC Flight testing: prototype dropsondes, telemetry chassis and AVAPS Software Technical engineering input Flight Operations input © 2009 Copyright University Corporation for Atmospheric Research