Showing papers on "GNSS augmentation published in 1996"

Integrity Monitoring of Integrated Satellite/Inertial Navigation Systems Using the Likelihood Ratio

Abstract: Global Navigation Satellite Systems (GNSS) have the ability to fulfill the navigation accuracy requirements of most applications. The systems do however lack continuity and integrity to meet the re ...

Software-based GIC/GNSS compatible GPS receiver architecture using TMS320C30 DSP processor

Abstract: The Global Navigation Satellite System (GNSS) refers to a world wide position and time determining system that uses satellite ranging signals to determine user position. It encompasses all satellite ranging technologies including GPS and additional satellites. The GNSS integrity channel (GIC) uses a network of ground stations at known locations to determine the status of every GNSS satellite in view of the network. Satellite health is then broadcast to GNSS users in real time via geostationary satellites. The paper describes the architecture of a software based GIC/GNSS compatible GPS receiver using the TMS320C30 DSP processor. The architecture is compatible with GPS, INM-3 GIC, the US WAAS GSO satellites and takes into account the future GNSS lightsats with GPS compatible architecture and carrier frequency offset from GPS L/sub 1/ frequency by approximately 1.023 MHz. The processor is used for correlation, filtering, decimation, demodulation, Viterbi decoding and navigation. The paper emphasises the Viterbi (k=7, r=1/2) decoder implementation in software for the WAAS and GIC satellites.

Design features of D-GNSS reference stations

Abstract: Differential GPS (DGPS) navigation systems have been in use for several years now in order to improve upon the stand-alone GPS navigation accuracy capability and, to a limited extent, integrity. Such systems became even more important with the introduction of the US DoD's selective availability (SA) policy, whereby unauthorised users are denied access to the full GPS accuracy. Since the emergence of conventional or local DGPS, further concepts, covering larger areas, have evolved. Networked differential augmentation systems (NDASs) have been employed to provide improvements in navigation accuracy over areas as large as the North Sea. The wide area differential (WAD) augmentation concept represents further improvement and is capable of providing both integrity and correction information over an entire continental region, or even globally. A fundamental part of any differential system is the reference station (RS), upon which all the integrity and differential correction information is based. In general, the RS architecture should take into account various important points relating to requirements for site location, hardware and software, potential for self-monitoring, data archiving and checking, availability and continuity of operation, etc. There is a fundamental need for a generic design capable of being used in any situation. There is a need to develop an expandable and inter-operable RS architecture. This paper discusses some of the issues which should be considered in order to realise such an architecture.