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) Echo Refracted rays n=0 n>0 n<0

33 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 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 2 nd ): 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  f 0 =1.59 MHz. Combine with low R (~ Ohm). Result: sharp (Q=15-20) response curve for several different configurations. Frequency generator; driving frequency shown in kHz Input signal and RLC response At/near central frequencyFar from central frequency

7 Receiver: main filter (cont.) VCVS active filter (1 op amp): amplification over desired range, but broader rolloff than RLC High response near f 0 (~1.5 MHz) Circuit Rolloff example far from f 0 (here: 599 kHz)

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

9 Receiver: main filter (cont.) 1 st -order Butterworth implemented as Sallen-Key active filter (1 op amp): stable f<f 0: low response f~f 0 : amplification (filter~inverter) f>f 0 : lower response

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

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: 1.Board inspection/connectivity of circuit cards by JSTD-certified engineer 2.Thermal/vacuum 3.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.