The Hatch filter is a code-smoothing technique that uses the variation of the carrier phase. It can effectively reduce the noise of a pseudo-range with a very simple filter construction, but it occasionally causes an ionosphere-induced error for low-lying satellites. Herein, we propose an optimal single-frequency (SF) divergence-free Hatch filter that uses a satellite-based augmentation system ...

GPS receivers nowadays provide a well established system for tracking of spacecraft in low-Earth orbit (LEO). In addition, GPS receivers serve as instruments for geodetic and atmospheric research on an ever growing number of science missions. The paper provides an overview of existing GPS receivers for LEO satellites, covering both fully space qualified as well as commercial-off-the-shelf (COTS...

Robust and reliable navigation of Unmanned Aerial Vehicles (UAVs) is an upcoming and promising field of research. In this paper we describe tightly-coupled initialization procedure using a monocular camera to resolve the GPS carrier phase integer ambiguities. This helps us obtain heading estimates during flight, using the GPS receivers. Further, we describe a sensor fusion structure which uses ...

Narrowband interference can severely degrade the performance of GPS receivers. Detecting the presence of interference and then characterizing it can lead to its removal. Receivers can be reconfigured to focus on other signals or satellites that are less vulnerable to that interference at that moment. Using hardware reconfigurability of FPGA receivers and characterizing the effect of narrowband ...

To do a better time comparison between high-precision clocks (such as a Cesium-fountain clock and Hydrogen-maser clock), we want to study and eventually lower the GPS carrier-phase time transfer noise. The GPS carrier-phase time transfer noise comes from four sources: GPS satellite, GPS signal path, ground receiving equipment (receiver and antenna), and data-processing algorithm. This paper foc...

Location-based online collaborative platforms are proving to be an effective and widely adopted solution for geospatial data collection, update and sharing. Popular collaborative projects like OpenStreetMap, Wikimapia and other services that collect and publish user-generated geographic contents have been fostered by the increasing availability of location-aware palmtop devices. These instrumen...

Global Positioning System (GPS) is a worldwide satellite system that provides navigation, positioning, and timing for both military and civilian applications. GPS based time reference provides inexpensive but highly-accurate timing and synchronization capability and meets requirements in power system fault location, monitoring, and control. In the present era of restructuring and modernization ...

This paper presents an overview of technical solutions for regional area precise GNSS positioning services such as in Queensland. The research focuses on the technical and business issues that currently constrain GPS-based local area Real Time Kinematic (RTK) precise positioning services so as to operate in future across larger regional areas, and therefore support services in agriculture, mini...