Full Mission Simulation: Second Teleconference

1. Full Mission Simulation:Second Teleconference West Virginia University Rocketeers Student team: N. Barnett, R. Baylor, L. Bowman, M. Gramlich, C. Griffith, S. Majstorovic, D. Parks, B. Pitzer, K. Tewey, E. Wolfe Faculty advisors: Y. Gu, D.J. Pisano, D. Vassiliadis May 22, 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) n>0 Refracted rays n=0 n<0 Echo Refracted rays

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

4. Summary of Changes Since Last Report Radio board (transmitter/receiver used to measure plasma density) Receiver filter: several versions tested, some successful PCB: v. 1 delivered. Revisions incorporated in v. 2. Control and data acquisition software: in development Main board (sensors: orbital and rotational motion, temperature, magnetic field) Sensor calibration: ongoing PCB v. 3 (minor changes from 2nd): ready to be ordered Servo for energetic-particle detector included in PCB v. 3 Independent testing by ABL.

5. Receiver: main filter • State-variable active filter: implemented with NJM1238 quad op amp, shown on perf board • Stability issues: oscillations • Autonomous (similar to standing waves); input ignored • Clearest between op amps 2-3 and 2-4.

6. Receiver: main filter (cont.) RLC passive filter: L=1 mH & C=10 pF  f0=1.59 MHz. Combine with low R (~50-100 Ohm). Result: sharp (Q=15-20) response curve for several different configurations. At/near central frequency Far from central frequency Frequency generator; driving frequency shown in kHz Input signal and RLC response

7. Receiver: main filter (cont.) VCVS active filter (1 op amp): amplification over desired range, but broader rolloff than RLC Rolloff example far from f0 (here: 599 kHz) Circuit High response near f0 (~1.5 MHz)

8. Receiver: main filter (cont.) 1st-order Butterworth implemented as Thomas-1 active filter (3 op amps): unstable, similar to state-variable filter. Output unstable, sensitive to capacitive coupling; easily breaks up into nonlinear, autonomous oscillations Input (sinusoidal) vs. output (flat lines) Schematic

9. Receiver: main filter (cont.) 1st-order Butterworth implemented as Sallen-Key active filter (1 op amp): stable f~f0: amplification (filter~inverter) f<f0: low response f>f0: lower response

10. Main filter: summary of responses RLC, passive (0) VCVS, active (1) Butterworth as Sallen-Key, active (1) • = filter is • stable, • amplifies input, • amplification occurs over bandpass region centered at design f0 Butterworth as Thomas-1, active (3)

11. Programmable Circuit Elements • The ColdFire PIT is used to control the digital capacitor. • Earlier we could only control one capacitor (images on right). • Currently we can control simultaneously multiple capacitors: useful in extending range or resolution of effective capacitance.

12. Radio PCB • v.1 delivered Transmitter Receiver

13. Radio PCB (cont.) • Revisions incorporated into v. 2 (receiver shown below)

14. Main Board • Background: the main board was completed in April. • Sensor calibration is ongoing. • Data storage: transition to binary files, more efficient storage.

15. Main Board: PCB v. 3 • Minor revisions have been made based on feedback from tests on v. 2. • In addition, to complement the plasma board operation, we have added an energetic-particle sensor operated by a servo. • Image on right: PCB design without servo leads.

16. Main Board: PCB v. 3 (cont.) • Image on right: new PCB design including servo leads.

17. Main Board: Other Tests • 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 and several breakouts during the same run. The LED on the left represents a servo for the energetic-particle sensor (not connected).

18. Main Board: Other Tests 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)

19. Independent Testing at ABL • Two students will take the main board to ABL; will participate in tests along with ABL staff. • Tests planned: • Board inspection/connectivity of circuit cards by JSTD-certified engineer • Thermal/vacuum • Vibration: • Sine sweep • Random 4. Impulse/shock acceleration (classical shock or SRS). • Test schedule: 2 days at end of May/beginning of June.

20. Vibration Testing • ABL will build a basic fixture to mount payload plate. • We have provided them with specifications for plate and canister

21. Vibration Testing (cont.) • Alternatively the plate will be mounted on the canister, and the canister will be bolted on vibration platform

22. Vibration Testing (cont.):Impulse Specification • We have specified the impulse using the RockOn 2009 acceleration profile.

23. Overall Analysis Launch readiness: we are still working on several issues related to the radio reception and control. We focus on two areas in particular: 1. We have several versions of stable filters in the frequency range of interest and we need to test them against each other. 2. The antenna transmission/reception tests indicate inductive (magnetic) rather than RF coupling. This is probably due to a mismatch in the circuit impedances. Otherwise we are now integrating the radio board!

24. Lessons Learned Improvements: • We are much more familiar with several sensor and electronics issues and know how to resolve them than we were a month ago. • Logistics problems have improved and we are now in a good operational cycle. Unresolved issues: • Instabilities in the radio filters are delaying the integration of the radio experiment.

25. Conclusions Issues and concerns: Stable active filters have been identified; final selection needs to be done. Transmission/reception tests are continuing. Summary/Closing remarks: The main board will be taken to independent testing at the end of the month. There is additional work to be done on several radio board components.