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September 3, 2004 :: No. 30

CSUF Graduate Students Investigate Delays in GPS Signals

Ten Cal State Fullerton graduate students majoring in math have forsaken the beach to spend the summer in a computer lab, working on a project for Raytheon Co.

The students utilized what they’ve learned in the classroom, putting it to practical use in the culminating project required for their master’s degree.

They have been investigating the delays in Global Positioning System (GPS) signals as they travel through the ionosphere, an area of the earth’s atmosphere where incoming solar radiation affects the transmission of radio waves.

“When the signals go through the ionosphere, it can throw off the measurement of the position,” says John G. Pierce, professor of mathematics, one of two faculty members working with the students. To compensate for the delay in the signal, GPS sends and receives two frequencies. But the delay, adds Pierce, “can be very crucial when GPS is being used for airplanes and measuring altitude.”

The main purpose of the students’ work was to develop a computer program that would help Raytheon determine how best to place new ground stations to estimate the delays, says William B. Gearhart, professor of mathematics.

Raytheon awarded an $18,414 summer contract for the students’ efforts.
Participants in the project were: Edward Can and Michael Vodhanel of Garden Grove, Tracy Grover of Lake Forest, Hannah Hong of Artesia, Jay Nguyen of Anaheim Hills, Lorena Ortiz of Norwalk, David Peterson and Eric Ratzlaff of Fullerton, Kevin Takeuchi of Yorba Linda and Tyler Wilson of Pullman, Wash.

Media Contacts:  

John G. Pierce, professor of mathematics, at 657-278-2779 or

William Gearhart, professor of mathematics, at 657-278-3184 or

Pamela McLaren of Public Affairs at 657-278-4852 or