This paper presents hardware-in-the-loop results that experimentally demonstrate precise relative navigation for true formation flying spacecraft applications. The approach is based on carrier-phase differential GPS, which is an ideal navigation sensor for these missions because it provides a direct measure of the relative positions and velocities of the vehicles in the fleet. In preparation fo...

From the wide range of methods available to landslide researchers and practitioners for monitoring ground displacements, remote sensing techniques have increased in popularity. Radar interferometry methods with their ability to record movements in the order of millimeters have been more frequently applied in recent years. Multi-temporal interferometry can assist in monitoring landslides on the ...

The location error of uncorrected data from Global Positioning System (GPS) collars range from ca. 45.5 to 65.5 m (Rempel et al. 1995). Improvements that potentially could reduce locational error to <10 m include correcting systematic-bias by reference to GPS data collected at a known position (differential correction), increase in the proportion of positions based on ranging 4 rather than 3 sa...

Ž . The use of the Global Positioning System GPS technology has become increasingly incorporated into airborne remote sensing applications over the past decade. While GPS positioning results may prove adequate for several applications at present, users should expect to experience degraded positioning accuracies over the next few years due to auroral substorm activity. Such degraded accuracies w...

The SBAS, satellite-based augmentation system, is basically the wide-area differential GPS (WADGPS) effective for numerous users within continental service area. For a practical investigation of wide-area augmentation technique, the authors have implemented the prototype system of the SBAS. It has achieved positioning accuracy of 0.3 to 0.6 meter in horizontal and 0.4 to 0.8 meter in vertical, ...

In 1996 and 1997 a monitoring network was set up at the translational slide of Vallcebre. Fourteen boreholes were equipped with piezometers, wire extensometers and inclinometers. Since then groundwater levels changes and wire displacements have been automatically recorded every 20 minutes. Superficial displacements have been periodically measured with differential GPS. The monitoring network ha...

The differential global positioning system (DGPS) transmits a GPS enhancement signal using a top-loaded monopole antenna in the medium frequency range. The top-loaded antenna in the medium frequency band can attain a radiation efficiency on the order of 10%. The antenna ground plane characteristics affect the antenna radiation efficiency. To improve the radiation efficiency, it is necessary to ...

This paper reports on research related to avoiding collisions in construction sites using differential GPS technology. In this project, the researchers developed and implemented a system where GPS technology was used in tracking a single vehicle and relaying its information to a central server. Using another simulated vehicle, the server evaluated collision scenarios and sent cautionary message...

In this paper we propose an efficient authentication and integrity scheme to support DGPS corrections using the RTCM protocol, such that the identified vulnerabilities in DGPS are mitigated. The proposed scheme is based on the TESLA broadcast protocol with modifications that make it suitable for the bandwidth and processor constrained environment of marine DGPS.

Tracked mobile robots in the 20 kg size class are under development for applications in urban reconnaissance. For efficient deployment, it is desirable for teams of robots to be able to automatically execute path following behaviors, with one or more followers tracking the path taken by a leader. The key challenges to enabling such a capability are (1) to develop sensor packages for such small ...