Brent M. Ledvina

Learn More
Since its creation, the Global Positioning System (GPS) has grown from a limited purpose positioning system to a ubiquitous trusted source for positioning, navigation, and timing data. To date, researchers have essentially taken a signal processing approach to GPS security and shown that GPS is vulnerable to jamming and spoofing. In this work, we(More)
A set of efficient algorithms for processing code-division multiple-access spread spectrum signals has been developed. They make use of bit-wise parallelism to process 32 samples simultaneously. These algorithms have been implemented in a real-time global positioning system software receiver. The receiver consists of a radio-frequency front end, a system of(More)
research interests are in the areas of ionospheric physics, space weather, estimation and filtering, and GPS/GNSS technology and applications. Mark L. Psiaki is an Associate Professor of Mechanical and Aerospace Engineering at Cornell University. He received a B.A. in Physics and M.A. and Ph.D. degrees in Mechanical and Aerospace Engineering from Prince-ton(More)
—Background theory, a reference design, and demonstration results are given for a Global Navigation Satellite System (GNSS) interference localization system comprising a distributed radio-frequency sensor network that simultaneously locates multiple interference sources by measuring their signals' time difference of arrival (TDOA) between pairs of nodes in(More)
This article is a review of Global Navigation Satellite Systems for space scientists who are interested in how GNSS signals and observables can be used to understand ionospheric dynamics and, conversely, how ionospheric dynamics affect the operational capabilities of GPS. The most common form of GNSS is the Global Positioning System (GPS); we will first(More)
The Global Positioning System, or GPS, is a key technology for both the civilian and scientific research markets. GPS provides users with precise geodetic positioning and time determination. Most GPS receivers require specialized hardware and complex software to operate. One receiver, originally designed to run in DOS, will be the focus of a code migration(More)
  • 1