Aerospace Digital Communication Instrument

Senior Design Presentation

Team Members

Alan PritchardComputer Engineering

MCU ProgrammingGUI Design

Brandon HodaTeam Leader

Electrical EngineeringHardware Development

MCU Programming

Reggie RobyElectrical Engineering

Hardware DevelopmentPCB Layout

Overview• Introduction

– Problem– Solution

• Constraints– Technical– Practical

• Hardware Block Diagram• Components• Design II

– New Sensor– PCB Layout– Enclosure

Introduction

• ADCI is a communication device• Used in high-altitude balloons• Will measure temperature, altitude, and

location• Will contain two-way communication device• For Aerospace Engineering Department

Problem

• Current unit is…– Too heavy– Expensive– Consumes too much power

• Only the location is currently transmitted

Solution

• New transmission device– Smaller– Less weight– Less power– Less expensive– More features

Technical ConstraintsName Description

Distance The ADCI must be able to communicate more than 100 miles atground level. It must also communicate at an altitude of morethan 10 miles.

Operating Temperature

The ADCI must operate within a temperature range of -70°C to50°C.

GPS and Altitude Precision

The ADCI must measure location and altitude with a 50-meterresolution.

Temperature Reading Range

The ADCI must accurately measure temperature from -40°C to50°C ± 1.0°C.

Battery Life The ADCI must run on a battery for more than 2 hours undernormal operating conditions; transmitting data at 1 minuteintervals.

Interfacing The ADCI must be able to interface with differentcommunication devices.

Practical Constraints

Name Description

Sustainability Ruggedness The ADCI must be able to survive the flight and the landing of the balloon.

Sustainability Upgradeability The ADCI must use the best sensors in the price range and allow more sensors later.

Ruggedness

• ADCI must survive at high altitude– Low temperature– Water vapor– Wind

• Landing is most important– Impact on hard ground– Dust– Will not protect against water landing

Upgradeability

• Future considerations– Other sensors

• Atomic IMU 6 degrees of freedom

– Adding a camera– Control over balloon direction

Hardware Block Diagram

GPS unit• GPS unit is part of Cell module• Sends 5 strings of NMEA data• $GPGGA and $GPRMC strings are used by ADCI

Temperature Sensor

Temperature Sensor

• DS18B20 Digital Temp Sensor (TO-92 Package)• Converts analog voltages to a digital binary signal onboard• Measures Temperatures from -55°C to +125°C (-67°F to +257°F)

Digital Temperature Sensor Diagram [1]

Data Logger

Data Logger

•Vdrive 2 is capable of storing 4GB of data•Uses standard USB flash drive as storage medium•Automatically detects and begins to write to the Jump drive

V2Drive [2]

Battery Information

• Primary Lithium thionyl chloride Battery or Li-S0Cl2• 3.6V per cell.• Use a total of 4 in series to get 14.4V rail• Supply 2400mAh power• Temperature operating range of -55°C to +85°C• Standard AA cell size

Tenergy Battery [3]

Operating Time

• The module uses 90mA while not sending a message• The max current spike measured was 180mA while

sending a message• All currents measured at 14.4V rail

hmA

mAh13

180

2400Worst case battery life:

Cell module

• Sends and receives SMS text messages• Sends GPS NMEA data to MCU• Uses AT&T wireless service• Uses a pre-paid SIM Card for no monthly fee

Terminus cellular module with GPS [4]

Design 1 Test Run

Design II

• Need a real test flight

Current Progress• External temp sensor• Pressure sensor• Design PCB• Mount in an enclosure

Testing

• Was tested in Gulfstream’s high-altitude chamber

• Endured a temperature of -60°C for a one hour period on a breadboard

• Data was successfully saved to the on board memory

• Messages were received as expected via text messaging

New Sensor

SCP1000 barometric pressure sensor

Schematic Drawing

PCB Design

Enclosure

7.1 in x 4.7 in x 3.5 in

References• [1] Maxim IC “DS18B20.pdf". [Online]. Available:

http://datasheets.maxim-ic.com/en/ds/DS18B20.pdf. Accessed November 30, 2009.

• [2] Mouser Electronics “VDRIVE2 FTDI Interface Modules & Development Tools”. [Online].Available: http://www.mouser.com/Search/include/LargeProductImage.aspx?path=ftdi/lrg/vdrive2.jpg. Accessed November 30, 2009.

• [3] Tenergy Battery “Tenergy Primary Lithium thionyl chloride Battery AA Size 3.6”. [Online]. Available: http://www.tenergybattery.com/components/com_virtuemart/shop_image/product/1025d926ca9a7f365a7a443dc6460d07.jpg. Accessed November 30, 2009.

• [4] Terminus “Terminus GSM/GPRS Terminal w/Python and GPS”. [Online]. Available: http://www.semiconductorstore.com/Pages/asp/Item_MoreImages.asp?ItemNumber=GSM864QV1.1. Accessed November 30, 2009.

Questions?