1. Full Mission Simulation Test Report West Virginia University Rocketeers Students: N. Barnett, R. Baylor, L. Bowman, M. Gramlich, C. Griffith, S. Majstorovic, D. Parks, B. Pitzer, K. Tewey, E. Wolfe Faculty: Y. Gu, D.J. Pisano, D. Vassiliadis May 12, 2010

2. Atmospheric/Plasma Science Payload 1. Atmospheric temperature. Processes: atmosphere heating/cooling mechanisms. Objective: identify layers based on temperature profile 2. Terrestrial magnetic field. Processes: field controls charged-particle motion. Objectives: –Measure vector B, dependence on altitude, geocentric distance. –For high S/N: detect low-frequency waves 3. Plasma and energetic particles. Processes: solar UV produces ionosphere >85 km. Cosmic rays produce avalanches of particles. Objectives: –Emit radio pulse which is reflected where index of refraction=0 –Measure density profile; identify E layer peak –For high-activity conditions: high-density patches descend to E- layer altitudes (“spread-F” effect) Echo Refracted rays n=0 n>0 n<0

3. 3 WVU in RockSat 2010: Functional Block Diagram Power Supply Thermistor uMag G uController Flash Memory RBF Swept-f Pulse Tx Power flow Comm/Con Data flow Z Accel Gyro Main BoardRadio Board Optical Port ADCADC Legend Fixed-f Pulse Tx Pre-amp & Power filter Super het LO Amplifier IF Inertial Sensor Regs G ANT Power C&DH Sensors RF in uController ADCADC Flash Memory ANT RF out

4. Changes Since Subsystem Integration -Main board (sensors for: orbital and rotational motion, temperature, magnetic field) -All sensors and electrical interfaces: tests completed -Flight software, incl. data acquisition and storage: tests completed -Servo for CR detector included in PCB -Sensor calibration: ongoing -Independent testing by ABL: electrical, mechanical, vibration. -3 rd version of PCB (minor changes from 2 nd ): ready to be ordered -Radio board (sensors for plasma density) -Receiver (Rx) active filter: redesigned (two versions: state-variable and VCVS), in testing phase -Rx detector: two designs (analog circuit with diode vs. AD637 converter) compared; analog circuit was chosen -Tx/Rx antennas: several prototypes constructed; in testing phase -PCB: completed -Control and data acquisition software: in development -Canister replica completed

5. Main Board The main board was completed in April. Since then the flight software, incl. sensor control, and data acquisition/storage, was finished and tested. The main board has been mounted on the Makrolon along with power supply, G switch and accelerometer/gyro board

6. Radio Board: PCB Design Several board components have been redesigned Top image: PCB design Bottom image: the PCB showing the microprocessor and flash memory, power supply, RBF and G switch, and receiver active filter. The detector has since been added at the center.

7. Test Description: Main Board -Electrical interfaces/connectivity (transistor pins corrected; breakout headers added; analog I/O utilized for battery voltage sensor; connection to IMU resolved) -Mechanical fits (hole-fastener fits; breakout boards added; working area added where accel/gyro used to be; will be used for CR detector/other prototyping) -Sensor tests: completed (gyro replaced) -Data handling: completed (collected at 1000 Hz; verification LEDs blinking every ½ second; still need to save as calibrated binary data) -Calibration: not completed -End-to-end (flight) test: completed -Length of tests: 3-7 minutes -Software debugging: appears complete (Programmable Interrupt Timer/PIT used; all MOD analog and digital pins configured)

8. Test Description: Radio Board -Active filter: comparison of 3 designs (state-variable, biquad, VCVS; electrical connectivity (breadboard vs. perf board); choice of op amp types (operating voltages; slew rates) -Detector: comparison of two designs -Antenna: Inductive vs. RF coupling -Calibration: not completed -End-to-end test: not completed -Software: control of digital components (cap is close to completion; potentiometer incomplete)

9. Test Results -In the following slides we present and discuss selected results from the two boards.

10. Test Results (1): Main Board Testing the flight software on the main board. Shown on the right is the disassembled board during such a test.

11. Test Results (2): Main Board Sensors Data acquisition of individual sensors. Top image: data acquisition from the high-rate sensors (gyro and accelerometer) on the breakout boards. Bottom image: the main board assembly during the same run. The LED on the left represents a servo (not connected here).

12. Test Results (3): Circuit Elements In order to tune the Tx/Rx pair we use digital circuit elements. Image on right: debugging the digital resistor.

13. Test Results (3): Circuit Elements The ColdFire PIT is used to control the digital capacitor and the serial peripheral interface (SPI) is used for the resistor. Top image: running a test on the MAXIM capacitor and recording the reactance. Bottom image: results from a test on the capacitor: PIT pulses delivered versus measured capacitance.

14. Test Results (4): Detector Design The receiver’s detector rectifies the active-filter voltage and turns it into DC (right image). Two alternative designs (top images) were compared. 1. Analog circuit (detector with backdiode):2. AD637 converter: Green: high-pass filter Red: half wave rectifier Blue: low-pass filter Brown: AD8099 op amp w/ squaring FB loop Digital oscilloscope output illustrating half-wave rectification of AC input

15. Test Results (4): Detector Design Red is the output voltage when frequency scan was performed at 3V p-p, while blue is at 2V p-p. The wobble is well within measurement error, no more than one millivolt. The output amplitude is monotonic (actually linear) with input However, only over a narrow input voltage range Conclusion from these and other tests: analog circuit is satisfactory, chosen over converter. The ideal detector output is 1) DC, 2) constant over a wide frequency range, and 3) linear (or at least monotonic) with input amplitude. Below are 2 results from the analog circuit:

16. Overall Analysis Launch readiness: we are still working on several issues related to the radio reception and control. The following issues are problematic: The active filter in two realizations (state-variable, biquad) is not stable above 1.1 MHz (needs at least 1.6 MHz). We may resort to the simpler VCVS version which is more stable. The antenna reception is weak and indicates inductive (magnetic) rather than RF coupling. Otherwise the board is very similar in hardware (PCB, processor, data acquisition, etc) to the main board which has been ready for some time.

17. Lessons Learned Improvements: Logistics problems have improved and are now in a good timing. We are much more familiar with several sensor and electronics issues and know how to resolve them than we were a month ago. Task allocation has improved, but is still not perfect. Unresolved issues: Basic-research complications in some components are delaying the construction of the radio experiment.

18. Conclusions Issues and concerns: –Active filter design is evolving. –Transmission/reception tests are continuing. Summary/Closing remarks: -The main board tests have been completed and independent testing has been scheduled. -There is additional work to be done on several radio board components.