Wireless TPS Sensors Detailed Design Review February 12, 2008 Jesse Pentzer John Sochacki Brandy Holmes Chris Johnson Lucas Wells

2 Outline Introduction PCB Sensor Node Software Receiver Node Software X-Jet Packaging VAST Packaging Timeline Budget

PIC XBee Amplifier LDO Regulator CJCs Pressure Sensor

Pressure CJC XBee LDO Amp RTD

Newest RevisionAir-wires will be resolved through testing

Final Concept

Software Flow Sensor Node Poll of Sensors –I2C (pressure sensor) –A/D (RTD temp. sensor) –SPI (3 thermocouple temp. sensor) Communication –USART (XBEE transceiver) Data Structure Union with Array –Redundant Send

Error Reduction Program Lockups –Conditional Locked Loops –Watchdog Timer (WDT) Data Reliability –Redundant Data Use PIC EEPROM to store old sensor data –Data Comparison

Error Reduction Cont’d Code Protection Power Problems –Brown-Out Reset (BOR)

Rabbit RCM 4510W

Receiver Node Data Flow

LabVIEW Interface Communications Parameters Thermal Coupler graph Pressure graph RTD graph Data Storage in File

Configure Serial Port Set Termination Character Read Data for buffer Write data to serial port Set XON and XOFF Characters Set I/O Buffer Size Write Data to File Display Data on Graph LabVIEW Logic Diagram Communication Parameters (user input) Close Session

16 X-Jet Preparation Using an aluminum sheet metal box to house electronics. Discs of TPS material allow thermocouples to measure temperature along a centerline through block. Static tube allows pressure measurement inside X-Jet

17 X-Jet Preparation - Progress

18 Assumptions: –TPS properties constant –1-D heat transfer along centerline of TPS Thermal X-Jet Model Heat Flux Node: Interior Node: Convection Node:

19 Thermal X-Jet Model – Current Results Heat Flux at q=10000 W/m^2

20 Four sensor nodes and the receiver node will be flown. Pressurized capsule allows the balloon’s internal pressure to be measured. Capsules made of extruded polystyrene insulation foam. VAST Flight

VAST Flight: Progress

22 Timeline

23 Beginning Budget$10,943 Shop and UI Fee$1,360 Travel Allocation$7,343 Beginning Spending Budget$2,240 Current Spending Left$957 Budget Status

Closing PCB and Programming are our biggest challenges at this time We are within budget Still on track to meet all goals