Global Positioning System (GPS)
Differential GPS
The Avionics Engineering Center has extensive experience and expertise with the development, assessment, implementation, and demonstration of precision approach and landing systems. This expertise includes work with a variety of Differential Global Positioning System (DGPS) implementations, including the Local Area Augmentation System (LAAS) and Wide Area Augmentation System (WAAS).
Figure 1: DC-3 flying a low approach over the LAAS-DGPS
Multipath Limiting Antenna (MLA) during testing
at the Ohio University Airport (UNI)
Since 1983, Center personnel have been involved with the design, testing, and application of Differential Global Positioning System (DGPS) to support precision approach and landing operations. The Center initially partnered with NASA Ames Research Center to use DGPS for supporting helicopter landings. Since this initial effort, the Center GPS program has continued to grow. Subsequent research efforts included:
- Developing a flight reference/autoland system using kinematic GPS techniques for NASA’s Boeing 737 research aircraft (1992)
- Completing and successfully flight testing, the first code-phase DGPS prototype that satisfied both sensor accuracy and total system error requirements for Category IIIb approach and landing operations using a United Parcel Service Boeing 757 (1994-95)
- Applying DGPS to support airport surface operations (1995); successfully completing the design and flight test of the first prototype LAAS with an integrity monitoring system suitable for Category IIIb using FAA’s Boeing 727 (1997)
- Completing the design and flight test of the first differentially-corrected pseudolite integrated into the LAAS (1998)
- Demonstrating LAAS as a viable means for supporting airport surface operations during FAA/NASA evaluation programs conducted at the Dallas/Fort Worth International Airport (1999-2000)
Because of the experience gained since 1983, Center personnel have been invited to participate as key technical advisors to the FAA’s Satellite Program Office supporting both LAAS and WAAS programs. Center personnel actively participate in the FAA’s LAAS Siting Manual Working Group and are leading the research efforts sponsored by the Office of Aviation System Standards to develop flight inspection concepts for both WAAS and LAAS.
In the area of Advanced Surface Movement, Guidance, and Control Systems (A-SMGCS), Center personnel have supported RTCA efforts for developing and validating performance requirements for the application of satellite technology as a means of supporting airport surface operations (RTCA, SC-159). Center personnel are knowledgeable in the area of GPS/LAAS multipath. Center personnel, working with industry partner dB Systems, have developed the only antenna system that effectively mitigates the effect of ground reflections on the LGF. Also, the Center currently has a principle role in the development and validation of the LAAS multipath model for the FAA.
In addition to an experienced staff, the Avionics Engineering Center facilities include a permanently installed prototype LGF at the Ohio University Gordon K. Bush Airport (UNI), a mobile LGF that can be used to support site assessments and demonstration activities, multiple LAAS data collection systems, and Ashtech Z-12 based truth reference systems
Figure 2: Avionics Engineering Center equipment
near the FAA’s 727 during the first LAAS prototype tests
CORS Network
The Avionics Engineering Center maintains two differential GPS ground reference stations as a part of a local CORS network. One station is located in Stocker Center on the Ohio University Campus; the other station is located at the Ohio University Airport in Albany, OH (UNI).
The GPS Team
- Frank van Graas, Ph.D.,Russ Professor
- Michael Braasch, Ph.D.,Thomas Professor
- Chris Bartone, Ph.D.,Associate Professor
- Maarten Uijt De Haag, Ph.D.,Associate Professor
- David Diggle, Ph.D.,AEC Associate Director, EECS Adjunct Assistant Professor
- Michael F. DiBenedetto, Ph.D.,AEC Senior Research Engineer, EECS Adjunct Assistant Professor
- Trent Skidmore, Ph.D.,AEC Senior Research Engineer, EECS Adjunct Assistant Professor
- Andrey Soloviev, Ph.D., AEC Research Engineer
- Sanjeev Gunawardena, MSEE, AEC Research Engineer
