Beyond The Grid Square -- Fox# Experiments. Mark Spencer, WA8SME ARRL Education and Technology Program

Transcription

1 Beyond The Grid Square -- Fox# Experiments Mark Spencer, WA8SME ARRL Education and Technology Program

2 My Purpose Today To make the opportunities afforded by the Fox satellites accessible to schools outside the immediate University of interest, and to the general ham population Outline: 1. WRAPS portable antenna rotor system to access Fox and other satellites [Now] 2. Attitude Determination Experiment (Wobbler) [Tomorrow at 1055] 3. Maximum Power Point Tracking (MPPT) [Tomorrow at 1345]

3 Wobbler, RadFx, Antenna Pointing System WRAPS

4 WRAPS Design Goals Battery operated, portable satellite antenna rotor system Affordable alternative to the Yaesu G5500 Reproducible using commercial-off-the-shelf parts, minimum mechanical work, common hand tools only For work with ARROW or Elk hand held antennas Target audience: Schools to access Fox telemetry; and the Portable satellite operator Fulfill a Bucket List goal

5 WRAPS Design Result Power source: 12V DC battery (Yes! It works well and for a good long time on a single 9-volt battery) Affordable (all relative) G5500: $730, LVB Tracker $200, Cabling $100 Total $1,000 WRAPS: Parts minus shipping costs $275 Rotor control interface is organic to unit USB 9600 baud FTDI driver set/stable but some noise (unacceptable for packet reception I found out) New update XBee link SatPC32/EasyCom/SAEBreTrack protocol

6 WRAPS Limitations (What WRAPS is NOT) Small, light weight antennas ARROW/Elk only Not weather proof Not intended for 24/7, unattended operation Used beside operator and mounted on camera tripod limited safety shut off limit switches As designed is 360 degree AZ/90 degree EL Can be modified for 180 degree EL Added mechanical stress and complication Switch selectable North-stop/South-stop to mitigate 90 degree EL limitation Requires SatPC32 Rotor Set-up change

7 90 Degree EL Limitation Mitigation If satellite will pass through the North Set WRAPS for South-stop Set SatPC32 for South-stop, 90 degrees EL Park antenna at 180 AZ/0 EL, Point antenna south If satellite will pass through the South Set WRAPS for North-stop Set SatPC32 for North-stop, 90 degrees EL Park antenna at 180 AZ/0 EL, Point antenna south Results in no AZ wrap around problems

8 WRAPS Big Picture

9 Double Sided PCB/Position Resistor Mounts

10 PCB Parts Separated

11 WRAPS Main PCB (prototype)

12 Inside the box

13 Outside the box

14 Simple but it works

15 Fox Attitude Determination Experiment (Wobbler) The Second Increment

16 Attitude Determination Experiment (Wobbler) In addition to the communications package, Fox-1 will host an experiment payload. AMSAT is sponsoring a capstone project at Penn State University for the academic year... The project will involve designing and constructing an attitude experiment based on a 3- axis, micro-electro-mechanical gyroscope. The experiment data will measure the performance of the satellite s magnetic stabilization system...

17 Attitude Determination Experiment (Wobbler Experiment) Use gyroscopes to directly monitor satellite rotation around the X, Y, and Z axes Precedence has been to infer rotation rate from solar panel voltage/currents Gyroscopes contain an oscillating driving mass Oscillation proportional to direction and rate of rotation Oscillation converted to voltage

18 Wobbler In-classroom Simulator Simulator uses actual gyroscope devices to be flown Mounted on rotator to simulate on-orbit behavior Data linked off-platform like the actual satellite Manipulate the Wobbler board and see what data results Capture real satellite data and see the Wobbler board gyrations that produce similar data

19 Wobbler Circuit

20 Wobbler PCB

21 Wobbler Ground Station GUI GUI displays data transmitted by Wobbler board GUI also used to control rotator behavior (direction and rate of rotation) GUI dumps data to Excel for exploitation and graphing

22 Wobbler Ground Station GUI

23 Data Analysis, the real value Rotation Deg/Sec Level CCW 1 RPM Time in Seconds X Z(X) Y Z(Y) 10 8 Tilt Around Y CCW 1 RPM 10 8 Tilt Around X CCW 1 RPM Rotation Deg/Sec Time in Seconds X Z(X) Y Z(Y) Rotation Deg/Sec Time in Seconds X Z(X) Y Z(Y)

24 Data Analysis, the real value

25 Fox2 Maximum Power Point Tracking (MPPT) Experiment The Final Increment

26 MPPT Task Rochester Institute of Technology (R.I.T.) engineering students have tackled the task of developing a maximum power point tracking (MPPT) system for use on the AMSAT Fox-2 satellite (see March/April 2013 AMSAT JOURNAL). Their task was to prototype a system that optimizes the power delivered by the satellite s solar panels.

27 MPPT Solar panel output dependent on illumination and operating temperature There is a sweet spot where output power is optimum Experiment purpose is to find and then keep the panels operating at the sweet spot Current (A) Optimum panel output Voltage (Load) Watts (W) I Watts

28 MPPT In-classroom simulator Allows students to experiment with solar panels to find power production curves and the sweet spot Develop circuitry to find and then operate the solar panel at the sweet spot Anticipated grade level 8-9 Anticipated grade level pre-engineering

29 Possible MPPT Circuit Block Diagram

30 Possible MPPT Circuit

31 MPPT Circuit in Operation

32 MPPT Circuit in Operation Current (A) Watts (W) I Watts Panel operated in sweet spot Voltage (Load) 0 FET control voltage

33 MPPT Classroom Simulator Components Controlled illumination source and solar panel MPPT Circuitry and computer interface

34 MPPT Illumination Source LEDs mounted inside of a PVC coupler fitting Portable and sealed to prevent outside light from getting to the solar panel You put the unit in controlled temperature environments I used my refrigerator

35 Solar panel with temperature sensor probe mounted in the other end of the PVC fitting Solar Panel Side

36 MPPT Circuitry Use a VOM and screw driver to vary the load on the solar panel and measure the output current/voltage Collect readings on a data table to generate the solar panel profile

37 Solar Panel Temperature Performance Profile

38 MPPT in Operation

39 MPPT Simulator Circuit based on PIC

40 MPPT PCB

41 MPPT GUI Displays temperature of the solar panel Allows for automatic MPPT operation based on temperature profile algorithm Allows for manual input of max/min voltage limits

42 Conclusion My Purpose: to make the Fox experiments more accessible beyond the Universities, including the average ham satellite enthusiast I have the hardware with me for up-close showand-tell if you are interested If you would like the specifics and details of any of the systems, send me a note at mspencer@arrl.org and I will provide a DropBox link to the information I have on hand.

43 Sponsors The efforts I detailed yesterday and today were made possible by: A grant from the ARRL Foundation An award from the YASME Foundation My thanks to them for their support

44 Questions that I can try to answer? If not, thanks for your attention and I will be around for one-on-one if you like. Mark Spencer, WA8SME mspencer@arrl.org or