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Laser Communications Group Members

Laser Communications Group Members. Team Mentor: Dr. William Wing Team Leaders:Matthew Johnson (ECE) Freddy Valenzuela (OPTI) Team Members: David Irwin (OPTI) Anurag Gupta (OPTI) Emma Harty (OPTI)

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Laser Communications Group Members

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  1. Laser Communications GroupMembers • Team Mentor: Dr. William Wing • Team Leaders:Matthew Johnson (ECE) Freddy Valenzuela (OPTI) • Team Members: David Irwin (OPTI) Anurag Gupta (OPTI) Emma Harty (OPTI) Tristan van Hoorebeke (OPTI)

  2. OBJECTIVES • Design a High Speed, Reliable Alternative Communication System for the University of Arizona’s Student Satellite Project • Demonstrate the feasibility of a two-way LASER communication link between a Small Satellite and a Ground Station • Build a ground-to-ground communication link as a test bed

  3. Design Goals • Uplink - send test data to satellite to confirm working link • Utilize LASER Communication System as alternative channel for TT&C team’s standard uplink (actual commands) • Full two-way LASER communication (uplink commands / downlink data)

  4. System Overview Ground Station Channel Satellite

  5. Groundstation Description • Control System (data and tracking) • Telescope & LASER Mounts • LASER & Transmission Optics • Receiving Package (photodetector) Satellite Description • Utilize Science Team’s Telescope & Processing Capability for LASER Communication • Transmission & Receiving Package.

  6. Uplink/Downlink Data Processing Sequence Transfer Optics Bits Bit Encoder to Symbol Channel (Atmos.) LASER Error Correction Symbol Recovery Receiving Optics Amplifier DMA Interface DCH BUS Bits

  7. Detection / Conversion Amplification Demodulation Error Correct. Detection / Conversion Amplification Demodulation Error Correct. Overall System Block Diagram Atmosphere Satellite Groundstation Ground Telescope (Tracking Mount) OPTICAL BEAMS Satellite Telescope Optical Filtering Fine Positioning Optical Filtering Fine Positioning Ground Laser Modulation Satellite Laser Modulation Data Processing Tracking Control Data Processing Optical Signals Main CPU Science Team CPU/mem Electrical Signals

  8. Communications Protocol • 10Mbit/sec Data Rate • Manchester Encoded Data • Error correction • Packet (Frame) Protocol with Resend

  9. Manchester Encoding (2-PPM) • Two Position Pulse Modulation • 1 bit per symbol • Transmit power data-independent

  10. Error Detection / Correction • Utilize forward error control to handle as many errors as possible • Retransmission of packet (iff packet is destroyed)

  11. Forward Error Correction (cont.) • Example of an error correction IC is the National Semiconductor DP8400-2-E2C2 • It can correct 2 bit errors in a 16 bit data word + 6 check bits. This chip can also be cascaded to correct up to 3 bits • Propagation Delay is well within our desired data rate for single bit error correction

  12. Access Time

  13. Retroreflectors Retro-reflectors deviate light by 180 degrees independently of its angle of incidence. This means that any light incident on the surface will be reflected back along the same path that it came from

  14. Interfaces With Other Systems • Optical dichroic splitters to split light from Science Team’s telescope • Spacecraft CPU: compliance with DCH bus specifications (also utilize a direct memory access scheme to get to data storage) • Power: compliance with Power team distribution system • Guidance: Rely on GNC system for coarse orientation

  15. Opportunities For Student Involvement • LASER Research • LASER Modulation Circuitry • Encoding/Decoding Circuitry • Optic Train (For Ground link And Groundstation/Satellite Systems) • Interfacing With Other Teams’ Systems

  16. Involvement Benefits • Integration of Senior Project with SSP research • Leadership opportunities • Resume¢ material • Possible paid research (pending grant success)

  17. Benefits of LCS Experience • Chris Gee working on airborne laser at Boeing • Matt Gilbert worked a Co-op at IBM • Mitesh Patel worked a Co-op at Raytheon • Emma Harty hired at Ball Aerospace for the summer • Emma Harty and Jeff Moore received Honors Research Grants

  18. Contact Information For more information: • Matthew Johnson (mjohnson@u.arizona.edu) • Freddy Valenzuela (acv@bigdog.engr.arizona.edu) • Http://www.physics.arizona.edu/ssp/sti To fill out an online application: • Http://www.physics.arizona.edu/ssp

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