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SAW-Based RFID for NASA Ground Facilities and Planetary Habitats

SAW-Based RFID for NASA Ground Facilities and Planetary Habitats. Patrick W. Fink/Richard Barton October 13, 2008. Phong Ngo G. D. Arndt, Ph.D. Julia Gross Chau Phan David Ni, Ph.D. John Dusl Kent Dekome. Patrick Fink, Ph.D. Timothy Kennedy, Ph.D. Richard Barton, Ph.D. Greg Lin

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SAW-Based RFID for NASA Ground Facilities and Planetary Habitats

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  1. SAW-Based RFID for NASA Ground Facilities and Planetary Habitats Patrick W. Fink/Richard Barton October 13, 2008

  2. Phong Ngo G. D. Arndt, Ph.D. Julia Gross Chau Phan David Ni, Ph.D. John Dusl Kent Dekome Patrick Fink, Ph.D. Timothy Kennedy, Ph.D. Richard Barton, Ph.D. Greg Lin Emal Latifzai Robert Williams Yasser Haridi Kent Byerly, Ph.D. (Spatial Acuity) George Studor Robert Brocato (Sandia National Laboratories) Contributors

  3. NASA Use of 2.4 ISM SAW-Based RFID Courtesy AirGATE Technologies Courtesy RFSAW, Inc.

  4. SAW RFID – Sample Waveform

  5. Initial Passive, Wireless Sensor Applications • Major Challenges • For NASA sensor applications, often want many tags within interrogator field-of-view • Ranges > 100 feet are desired for many applications • Primary SAW material in use is very sensitive to temperature • Good for temperature sensing, but makes other sensors more challenging • Combination of these challenges prompted early applications based on: • Larger aperture interrogators + adaptive digital beamforming • Temperature sensing applications

  6. Waveform Correlation to Determine Temperatures and IDs Measured tag delay with temperature • Measured response • Composite signal from multiple tags + noise • Template response • Waveform obtained by a priori measurement • Analytically modified by range and temperature • Correlation matrix formed from measured response and modified template responses • Need to determine effect of non-zero cross-correlations on temperature and range accuracies

  7. Correlation simulation - background • 40-bit Global SAW Tag (GST) tags from RFSAW, Inc. • Simulation based on measured tag responses with simulated additive, white Gaussian noise; SNR = 20 dB • Composite signal formed from summation of 11 tag responses • All tags have same energy (suspected worst case) • Tags assumed at different ranges and temperatures • 2D correlation process • Straightforward entire waveform correlation • Suitable for RFID/sensor interrogation in which all IDs are known a priori • 21 time scale increments representing 105 C range • 21 time delay increments representing 210 ns range

  8. Correlation simulation – results (11 tags) Tag 1873 – strongest correlation in population Tag 1873 correlated with composite signal + noise. Tag 1873 correlated with noise, only.

  9. Successive interference cancellation required Tag 1858 – 2nd strongest correlation in 11 tag population Tag 1858 correlated after subtracting estimate of Tag 1873: correct peak is identified. Tag 1858 correlated with Tag 1873 present: false peaks.

  10. Correlation Simulation Results • Preliminary error statistics for 11-tag population: • Error in delay • Mean: 0.53 ns • Std. Dev.: 1.5 ns • Error in dilation • Mean: -0.09 °C • Std. Dev.: 0.21 °C • More simulations and tests required for statistical significance • Need to determine error dependencies upon number of tags in population

  11. Spatial Diversity to Isolate Sensor Clusters Collision avoidance plan: Correlations used to isolate tags within defined clusters Virtual (digital) beamforming limits collision from adjacent clusters

  12. 72-element Interrogation in Anechoic Chamber

  13. Direction of Arrival in Anechoic Environment

  14. Spatial diversity for collision avoidance [ Before – 2 tag responses – to be added] [ After – single tag response recovered ]

  15. Operation in KSC Cryogenics Laboratory

  16. Direction-of-Arrival: Two tags in clutter

  17. RFID Tag Applications – Lunar Outpost • Telemetry • Monitor tool exposure limits: temperature, shock, etc. • MMOD impact detection and location • Chemical and atmospheric sensing

  18. Applications – Lunar Outpost • Navigation • Lunar landing aids • Lunar “road signs” or “breadcrumbs” • Passive tag tracking RFID Tag Tracking

  19. Application: Environmental Facility Wireless Sensors • Adaptive interrogation of wireless temperature and pressure sensors • Goals: Tlow = 20K; 100s of T-sensors; 10s of pressure sensors JSC Chamber A T-sensor configuration on inner shroud JSC Chamber A (Vacuum & Thermal Cycle)

  20. Sensor coverage schemes for Chamber A Coverage from wall-based interrogators Coverage from floor-based interrogators

  21. Next Wave of Passive, Wireless Sensor Applications • Additional Challenges • Desire to integrate calibrated, passive commercial sensors with SAW devices • Acceleration, acoustic emission sensors are primary targets • Still need many tags within interrogator field-of-view and long ranges • Sample rates significantly higher than our temperature applications: > 10 kHz, compared to 1-3 Hz

  22. SNL Concept to Incorporate Commercial Sensors Sandia National Laboratory (SNL) concept: FET-loading of SAW IDT with passive sensor driving FET Interdigital Transducers (IDTs) Passive sensor types under evaluation: accelerometer, acoustic emission

  23. Application Example: White Sands Test Facility

  24. Application Example: Monitoring Cryogenic Fill Level 5 4 3 ... 2 1 SAW Tag Temperature Sensors

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