BalloonSat Telemetry Module

1. BalloonSat Telemetry Module Christopher Arthur Jonathan Berry Jeb Orr Project Final Design Review April 25, 2006 CPE 496-02, Spring 2006

2. Agenda • Project Summary • Accomplishments • Performance • Hardware and Firmware • Testing • Flight Results • Costs and Labor • Conclusions and Recommendations

3. Project Summary • BalloonSat Telemetry Module • Hardware Module • Sample analog or digital data • Transmit data back to the ground station in real time • Ground Station Software • Decode recorded data received by the ground station, output to CSV

4. Accomplishments • Produced two modules meeting the needs of the BalloonSat team • Samples up to eight channels at a continuous rate of about 1.5 Hz • Module transmits AX.25 frames containing a compact ASCII representation of the data:Example: NV4B>TLMTRY:7E836076 • Device is packaged in a robust, reusable aluminum enclosure

5. Accomplishments (continued) • Power consumption and weight requirements met with plenty of room to spare • Produced ground station software to automate the conversion of the ASCII hex data to voltage values; this software also produces CSV files for easy data analysis

6. Performance • All critical requirements met • Some capabilities not implemented • The flight date was a week sooner than expected; working module was ready on April 8 • Device limitations • Very little RAM • Only one timer • Codebase limitations • AFSK routine not interrupt-driven

7. Hardware • Two complete modules constructed • Only one small modification to schematic and PCB since preliminary design • Microcontroller device programmer breadboarded • COTS radio (Alinco DJ-C7T) required no modification

8. Firmware • Based on OpenTracker firmware as planned • Binary-to-ASCII hex conversion implemented in firmware • Compiler directive selects the number of channels to transmit • Status LED configured to light during transmission • AFSK accomplished with PWM of a timer pin in conjunction with a sinewave LUT • Transmission takes place at a constant rate with PTT de-asserted between packets • Flight duration timer shuts down module after specified number of packets

9. Testing • Functionality Testing • Basic prototype built for low-level AFSK testing • Results were not observable on ‘scope but audible tones were obviously correct • TNC Integration Testing • Code was written to transmit the same packet continuously • AFSK fed directly to TNC’s input; TNC decoded and displayed the data properly

10. Testing (continued) • Integration Testing with BalloonSat Package • Ground test conducted April 8, 2006 with a module on each of two different packages • Module was connected to payload power supply and BalloonSat team’s sensors • Test was successful • Encoding Reliability/Error Detection Testing • None implemented; relied on AX.25’s inherent frame-check sequence

11. AX.25 and AFSK Encoding Testing Achieved during integration testing with TNC Proper ADC data representation tested by stepping through voltage levels with a precision power supply On-air Data Transmission Testing In the lab during ADC calibration During the ground test During actual flight Testing (continued)

12. Testing (continued) • Ground Station Software Testing • Ground station software was tested with sample input file; sample input was successfully decoded • Test results reinforced with successful decoding of the ground test data

13. Flight Results • ORION-I – 10:50 a.m. April 9, 2006, NSSTC

14. Flight Results • Anomalous data noticed at 12:12 p.m. after 1 minute data loss; all data lost around 12:25 p.m. • Chase team met in Fyffe, AL to coordinate search (no position data available) • Around 1:30 p.m., first signals heard west of Fyffe • Direction finding led to house in Macedonia community of Jackson County where payload was recovered, 40 miles from the launch site • Large amount of data received from our module, which never stopped transmitting

15. Flight Results – Raw Data Sample NV4B>TLMTRY [04/09/06 12:11:11]:777D6B83 NV4B>TLMTRY [04/09/06 12:11:11]:787D6B81 NV4B>TLMTRY [04/09/06 12:11:12]:787D6B81 NV4B>TLMTRY [04/09/06 12:11:13]:787C6B81 NV4B>TLMTRY [04/09/06 12:11:14]:777E6B83 NV4B>TLMTRY [04/09/06 12:11:15]:777E6B81 NV4B>TLMTRY [04/09/06 12:11:17]:777E6B80 NV4B>TLMTRY [04/09/06 12:11:18]:787C6B81 NV4B>TLMTRY [04/09/06 12:12:12]:73626B69 NV4B>TLMTRY [04/09/06 12:12:15]:695D6B45 NV4B>TLMTRY [04/09/06 12:12:15]:3A826C00 NV4B>TLMTRY [04/09/06 12:12:17]:747B6C49 NV4B>TLMTRY [04/09/06 12:12:18]:5E4F6B53

16. Flight Results – CSV Data

17. Flight Results -- Data

18. Flight Results • ORION-II – 10:20 a.m. April 15, 2006, NSSTC

19. Flight Results • Flight was less successful—had difficulty decoding the packets sent • Noise may have been induced in module or in ground station • Some data was recovered • APRS Position data was lost again—radiolocation search proved unsuccessful • Last signal heard south-southwest of Section, Alabama as the balloon fell from the sky around 11:30 a.m.

20. Flight Results

21. Cost and Labor • Cost per unit was $249 ($260 budgeted) • $180 for radio • $20 for PCB • $49 for parts, enclosures, microcontrollers, etc. • Project took over 200 man-hours to complete

22. Conclusions • Project was a success • Future work is recommended to add functionality • Implementation of serial port and configuration utility • Implementation of interrupt-driven AFSK routine to allow higher ADC sampling rates; this may require a significant amount of work and could be suitable for a future design project

23. Questions?