Bio


I am the director of the wide-area differential Global Navigation Satellite System(GNSS) laboratory at Stanford University. My work focuses on implementing high-integrity air navigation systems. I am also active in the international standards bodies coordinating the use of GNSS to implement these systems.

Academic Appointments


  • Sr Research Engineer, Aeronautics and Astronautics

Honors & Awards


  • Leadership Award in Signal Design, GPS World Magazine (September, 2015)
  • Distinguished Service Award, Institute of Navigation (January, 2012)
  • Kepler Award, Institute of Navigation (September, 2010)
  • Thurlow Award, Institute of Navigation (January, 2008)
  • Fellow of the ION, Institute of Navigation (June, 2006)
  • Early Achievement Award, Institute of Navigation (June, 2000)

Boards, Advisory Committees, Professional Organizations


  • President, Institute of Navigation (2010 - 2012)
  • Member, Institute of Navigation (1994 - Present)
  • Member, IEEE (2014 - Present)

Professional Education


  • Ph.D., Stanford University, Applied Physics (1994)
  • M.S., Stanford University, Applied Physics (1990)
  • B.S., Rensselaer Polytechnic Institute, Physics (1987)

Current Research and Scholarly Interests


High integrity satellite navigation for guiding aircraft, including satellite based augmentation systems (SBAS) and advanced receiver autonomous integrity monitoring (ARAIM).

All Publications


  • Evolving WAAS to Serve L1/L5 Users NAVIGATION-JOURNAL OF THE INSTITUTE OF NAVIGATION Walter, T., Blanch, J., Phelts, R. E., Enge, P. 2012; 59 (4): 317-327

    View details for DOI 10.1002/navi.21

    View details for Web of Science ID 000209006500006

  • MATLAB Algorithm Availability Simulation Tool GPS SOLUTIONS Jan, S., Chan, W., Walter, T. 2009; 13 (4): 327-332
  • Worldwide Vertical Guidance of Aircraft Based on Modernized GPS and New Integrity Augmentations PROCEEDINGS OF THE IEEE Walter, T., Enge, P., Blanch, J., Pervan, B. 2008; 96 (12): 1918-1935
  • Robust Detection of Ionospheric Irregularities NAVIGATION-JOURNAL OF THE INSTITUTE OF NAVIGATION Walter, T., et al 2001; 48 (2): 89–100
  • Wide area augmentation of the global positioning system PROCEEDINGS OF THE IEEE Enge, P., Walter, T., Pullen, S., Kee, C., Chao, Y. C., Tsai, Y. J. 1996; 84 (8): 1063-1088
  • Orbital representations for the next generation of satellite-based augmentation systems GPS SOLUTIONS Reid, T. G., Walter, T., Enge, P. K., Sakai, T. 2016; 20 (4): 737-750
  • Preliminary availability assessment to support single-frequency SBAS development in the Korean region GPS SOLUTIONS Bang, E., Lee, J., Walter, T., Lee, J. 2016; 20 (3): 299-312
  • GNSS Integrity in The Arctic NAVIGATION-JOURNAL OF THE INSTITUTE OF NAVIGATION Reid, T., Walter, T., Blanch, J., Enge, P. 2016; 63 (4): 469-492
  • A Simple Position Estimator That Improves Advanced RAIM Performance IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS Blanch, J., Walter, T., Enge, P., Kropp, V. 2015; 51 (3): 2485-U960
  • GNSS Multipath and Jamming Mitigation Using High-Mask-Angle Antennas and Multiple Constellations IEEE TRANSACTIONS ON INTELLIGENT TRANSPORTATION SYSTEMS Heng, L., Walter, T., Enge, P., Gao, G. X. 2015; 16 (2): 741-750
  • Future Dual-Frequency GPS Navigation System for Intelligent Air Transportation Under Strong Ionospheric Scintillation IEEE TRANSACTIONS ON INTELLIGENT TRANSPORTATION SYSTEMS Seo, J., Walter, T. 2014; 15 (5): 2224-2236
  • Effects of solar cycle 24 activity onWAAS navigation SPACE WEATHER-THE INTERNATIONAL JOURNAL OF RESEARCH AND APPLICATIONS Datta-Barua, S., Walter, T., Bust, G. S., Wanner, W. 2014; 12 (1): 46-63
  • DME/TACAN interference mitigation for GNSS: algorithms and flight test results GPS SOLUTIONS Gao, G. X., Heng, L., Hornbostel, A., Denks, H., Meurer, M., Walter, T., Enge, P. 2013; 17 (4): 561-573
  • Critical Elements for a Multi-Constellation Advanced RAIM NAVIGATION-JOURNAL OF THE INSTITUTE OF NAVIGATION Blanch, J., Walter, T., Enge, P., Wallner, S., Fernandez, F. A., Dellago, R., Ioannides, R., Hernandez, I. F. 2013; 60 (1): 53-69

    View details for DOI 10.1002/navi.29

    View details for Web of Science ID 000339565800005

  • Incorporating GLONASS into Aviation RAIM Receivers International Technical Meeting of the Institute-of-Navigation Walter, T., Blanch, J., Choi, M. J., Reid, T., Enge, P. INST NAVIGATION. 2013: 239–249
  • Optimal Positioning for Advanced Raim NAVIGATION-JOURNAL OF THE INSTITUTE OF NAVIGATION Blanch, J., Walter, T., Enge, P. 2013; 60 (4): 279-289

    View details for DOI 10.1002/navi.49

    View details for Web of Science ID 000339567500003

  • Near Term Improvements to WAAS Availability International Technical Meeting of the Institute-of-Navigation Blanch, J., Walter, T., Phelts, R. E., Enge, P. INST NAVIGATION. 2013: 71–77
  • L1/L5 SBAS MOPS Ephemeris Message to Support Multiple Orbit Classes International Technical Meeting of the Institute-of-Navigation Reid, T., Walter, T., Enge, P. INST NAVIGATION. 2013: 78–92
  • Signal Deformation Monitoring for Dual-Frequency WAAS International Technical Meeting of the Institute-of-Navigation Phelts, R. E., Wong, G., Walter, T., Enge, P. INST NAVIGATION. 2013: 93–106
  • Results on the Optimal Detection Statistic for Integrity Monitoring International Technical Meeting of the Institute-of-Navigation Blanch, J., Walter, T., Enge, P. INST NAVIGATION. 2013: 262–273
  • GPS Signal-in-Space Integrity Performance Evolution in the Last Decade IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS Heng, L., Gao, G. X., Walter, T., Enge, P. 2012; 48 (4): 2932-2946
  • Satellite Navigation for Aviation in 2025 PROCEEDINGS OF THE IEEE Blanch, J., Walter, T., Enge, P. 2012; 100: 1821-1830
  • Statistical Characterization of GLONASS Broadcast Clock Errors and Signal-In-Space Errors International Technical Meeting (ITM) of the Institute-of-Navigation (ION) Heng, L., Gao, G. X., Walter, T., Enge, P. INST NAVIGATION. 2012: 1697–1707
  • OPTIMAL POSITIONING FOR ADVANCED RAIM International Technical Meeting (ITM) of the Institute-of-Navigation (ION) Blanch, J., Walter, T., Enge, P. INST NAVIGATION. 2012: 1624–1631
  • Availability Impact on GPS Aviation due to Strong Ionospheric Scintillation IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS Seo, J., Walter, T., Enge, P. 2011; 47 (3): 1963-1973
  • Correlation of GPS signal fades due to ionospheric scintillation for aviation applications ADVANCES IN SPACE RESEARCH Seo, J., Walter, T., Enge, P. 2011; 47 (10): 1777-1788
  • Reversion from L1-L5 Dual to L5 Single Frequency WAAS in the Presence of RF Interference IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS Jan, S., Walter, T., Enge, P. 2010; 46 (3): 1110-1126
  • RAIM with Optimal Integrity and Continuity Allocations Under Multiple Failures IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS Blanch, J., Walter, T., Enge, P. 2010; 46 (3): 1235-1247
  • Unaugmented GPS-Based Flight Inspection System IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS Kim, E., Walter, T., Powell, J. D. 2010; 46 (2): 717-724
  • Compass-M1 Broadcast Codes in E2, E5b, and E6 Frequency Bands IEEE JOURNAL OF SELECTED TOPICS IN SIGNAL PROCESSING Gao, G. X., Chen, A., Lo, S., De Lorenzo, D., Walter, T., Enge, P. 2009; 3 (4): 599-612
  • Characteristics of deep GPS signal fading due to ionospheric scintillation for aviation receiver design RADIO SCIENCE Seo, J., Walter, T., Chiou, T., Enge, P. 2009; 44
  • Position Error Bound Calculation for GNSS using Measurement Residuals IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS Blanch, J., Walter, T., Enge, P. 2008; 44 (3): 977-984
  • Wide area augmentation system-based might inspection system JOURNAL OF AIRCRAFT Kim, E., Walter, T., Powell, J. D. 2008; 45 (2): 614-621

    View details for DOI 10.2514/1.32531

    View details for Web of Science ID 000254761600029

  • Improving GPS-based landing system performance using an empirical barometric altimeter confidence bound IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS Jan, S., Gebre-Egziabher, D., Walter, T., Enge, P. 2008; 44 (1): 127-146
  • Understanding the GIOVE-B Broadcast Codes of the Galileo System 42nd Asilomar Conference on Signals, Systems and Computers Gao, G. X., Akos, D., Walter, T., Enge, P. IEEE. 2008: 2086–2090
  • Understanding PHMI for Safety of Life Applications in GNSS 2007 National Technical Meeting of the Institute-of-Navigation Blanch, J., Walter, T., Enge, P. INST NAVIGATION. 2007: 305–310
  • Adaptive Carrier Smoothing Using Code and Carrier Divergence 2007 National Technical Meeting of the Institute-of-Navigation Kim, E., Walter, T., Powell, J. D. INST NAVIGATION. 2007: 141–152
  • Model Analysis on the Performance for an Inertial Aided FLL-Assisted-PLL Carrier-Tracking Loop in the Presence of Ionospheric Scintillation 2007 National Technical Meeting of the Institute-of-Navigation Chiou, T., Gebre-Egziabher, D., Walter, T., Enge, P. INST NAVIGATION. 2007: 1276–1295
  • Galileo GIOVE-A Broadcast E5 Codes and their Application to Acquisition and Tracking 2007 National Technical Meeting of the Institute-of-Navigation Gao, G. X., De Lorenzo, D. S., Chen, A., Lo, S. C., Akos, D. M., Walter, T., Enge, P. INST NAVIGATION. 2007: 936–946
  • A Reference Point-based Precise Relative Positioning Method Using a Single Frequency Receiver 2006 National Technical Meeting of the Institute-of-Navigation Kim, E., Walter, T., Powell, J. D. INST NAVIGATION. 2006: 283–292
  • WAAS-based threat monitoring for a Local Airport Monitor (LAM) that supports Category I Precision Approach IEEE/ION Position, Location, and Navigation Symposium Rife, J., Pullen, S., Walter, T., Phelts, E., Pervan, B., Enge, P. IEEE. 2006: 468–482
  • Galileo-GPS RAIM for Vertical Guidance 2006 National Technical Meeting of the Institute-of-Navigation Ene, A., Blanch, J., Walter, T. INST NAVIGATION. 2006: 432–440
  • A development of WAAS-aided Flight Inspection Truth System 2006 IEEE/ION POSITION, LOCATION AND NAVIGATION SYMPOSIUM, VOLS 1-3 Kim, E., Peled, U., Walter, T., Powell, J. D. 2006: 61-70
  • Field Data Analysis for a Range-Based Local Airport Monitor for WAAS 2006 National Technical Meeting of the Institute-of-Navigation Seo, J., Rife, J., Pullen, S., Walter, T., Enge, P. INST NAVIGATION. 2006: 748–758