Aerospace Digital Communication Instrument Senior Design 1 Presentation

Team Members Alan Pritchard Computer Engineering MCU Programming GUI Design Brandon Hoda Team Leader Electrical Engineering Hardware Development MCU Programming Reggie Roby Electrical Engineering Hardware Development PCB Layout

Overview Introduction – Problem – Solution Constraints – Technical – Practical Hardware Block Diagram Parts and Progress Timeline

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 Constraints NameDescription DistanceThe ADCI must be able to communicate more than 100 miles at ground level. It must also communicate at an altitude of more than 10 miles. Operating Temperature The ADCI must operate within a temperature range of -70°C to 50°C. GPS and Altitude Precision The ADCI must measure location and altitude with a 50-meter resolution. Temperature Reading Range The ADCI must accurately measure temperature from -40°C to 50°C ± 1.0°C. Battery LifeThe ADCI must run on a battery for more than 2 hours under normal operating conditions; transmitting data at 1 minute intervals. InterfacingThe ADCI must be able to interface with different communication devices.

Practical Constraints NameDescription SustainabilityRuggednessThe ADCI must be able to survive the flight and the landing of the balloon. SustainabilityUpgradeabilityThe 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 Pressure Transducer – 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

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

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 Worst 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]

NMEA Data The ADCI reads in NMEA data from the onboard GPS unit Stores NMEA and sends it as a SMS message NMEA Data The ADCI reads in NMEA data from the onboard GPS unit Stores NMEA and sends it as a SMS message $GPGGA, , ,N, ,W,1,08,01.0,98.1,M,-28.4,M,,*62 $GPRMC, ,A, ,N, ,W,35.10,57.18,071109,,,A*7E UTC timeLatitudeLongitude UTC timeLatitudeLongitudeSpeedDate $GPGGA, , ,N, ,W,1,08,01.0,98.1,M,-28.4,M,,*62 $GPRMC, ,A, ,N, ,W,35.10,57.18,071109,,,A*7E UTC timeLatitudeLongitude Altitude UTC timeLatitudeLongitudeSpeedDate Num of sat.

NMEA to KML Files THE KML Generator 1.26 used to convert NMEA strings to KML KML Files are used by Google earth for plotting a Corse Benefits of KML converter Free Easy to use Quickly plots traveled Corse

Sample NMEA Code

What’s Left? Need a real test flight More testing to ensure consistent operation Design II Design and buy factory PCB Pressure sensor External temp sensor Mount in an enclosure

Timeline AugustSeptemberOctoberNovember Research Hardware Design Software Testing Prototype Design

References [1] Maxim IC “DS18B20.pdf". [Online]. Available: ic.com/en/ds/DS18B20.pdf. Accessed November 30, [2] Mouser Electronics “VDRIVE2 FTDI Interface Modules & Development Tools”. [Online].Available: drive2.jpg. Accessed November 30, [3] Tenergy Battery “Tenergy Primary Lithium thionyl chloride Battery AA Size 3.6”. [Online]. Available: ct/1025d926ca9a7f365a7a443dc6460d07.jpg. Accessed November 30, [4] Terminus “Terminus GSM/GPRS Terminal w/Python and GPS”. [Online]. Available: ber=GSM864QV1.1. Accessed November 30, 2009.

Questions?