This paper describes the design and testing of an aperture-coupled circularly polarized antenna for global positioning satellite (GPS) applications. The antenna operates at both the L1 and L2 frequencies of 1575 and 1227 MHz, which is required for differential GPS systems in order to provide maximum positioning accuracy. Electrical performance, lowprofile, and cost were equally important requir...

Persistent pseudorange biases constitute a serious potential integrity problem for differential GPS systems used in aircraft precision approach and landing. Various approaches to solve this problem are documented in the literature, including composite protection levels (PLs) that incorporate an explicit bias term in their mathematical expressions. A statistical characterization for such a PL wa...

The global positioning system (GPS) allows properly equipped users to determine their position based on the measured pseudoranges to at least four satellites. Differential GPS operation (DGPS) uses a reference station at a known location to calculate and broadcast pseudorange corrections to local users, resulting in improved user position accuracy. DGPS accuracy is limited by the ability of the...

Differential Interferometric Synthetic Aperture Radar (DInSAR) techniques have been recognised as well-suited for ground deformation monitoring applications. However, the spatially and temporally variable delay of the radar signal propagating through the atmosphere represents a major limitation to accuracy. The dominant factor to be considered is the tropospheric heterogeneity, which can lead t...

INMARSAT has designed a GPS (L1) transponder that will be included in their third generation satellites. This transponder will broadcast a pseudo-GPS signal that can be used for navigation and also for disseminating integrity data and/or differential corrections for the GPS satellites. This INMARSAT Geostationary Overlay (IGO) service will be used to enhance the performance of the GPS navigatio...

In this paper, vehicle relative positioning applied in Vehicle-to-Infrastructure (V2I) navigation is described. GPS positioning augmented with Ultra-Wideband (UWB) ranges is reviewed. The relative solution is implemented in an extended Kalman filter where differential GPS pseudorange, Doppler and carrier phase measurements are used in conjunction with UWB ranges measured between the vehicle and...

Many power grid applications rely on the time synchronized measurement data collected by phasor units (PMUs) and or Merging Units (MUs)). The synchronization of from multiple PMUs MUs relies global positioning system (GPS) to provide reference. civilian GPS receivers used in PMU operate according publicly available mechanism. Therefore, attackers can easily generate false signals with low-cost ...