Integral GPS and QZSS Ambiguity Resolution

Abstract

The US GPS and the planed Quasi Zenith Satellite System (QZSS) will enhance the capability of quickly resolving the integer cycle carrier phase ambiguities in precise differential positioning. The paper describes numerical analysis of the positioning performance of combined GPS-QZSS system. The current ambiguity resolution method is employed to resolve all cycle ambiguities of combined GPS-QZSS system. The performance of ambiguity resolution on a short baseline of 1 km in Tokyo is analyzed for different scenarios of the present GPS and combined future GPS-QZSS system. It is also analyzed in the Asian cities of Seoul, Beijing and Shanghai. The ambiguity fix percentage is adopted here for evaluating the performance of ambiguity resolution. It indicates that increasing the number of satellites has a benefit on the capability of getting quick ambiguity resolution. It also indicates that the ambiguity fix percentage with both GPS and QZSS is much higher than that with only GPS on the short-baseline operation.

Snow Water Equivalent of Dry Snow Derived From GNSS Carrier Phases

“…The performance has been improved over the last two decades, e.g., by using multi-GNSS measurements and fixing ambiguities of multiple constellations (e.g., joint GPS/Globalnaya navigatsionnaya sputnikovaya sistema (Glonass) fixing [30] and joint GPS/quasi-zenith satellite system fixing (QZSS) [31]), by code multipath estimation [32], by partial ambiguity fixing for faster fixing [33], and/or by partial integer decorrelation [34]. Fig.…”

“…We can obtain such fitted arcs by least-squares estimation of the snow parameter based on given fixed phase measurements and mapping functions. As the phase measurements of some satellites might be corrupted by receiver tracking errors or azimuthal inhomogeneities in the snow cover, we perform the fitting for each satellite pass separately, i.e., r kl 12,fitted = γm (31) with the stacked phase measurements of epochs t…”

Proposal for a Novel Remote Synchronization System for the On-Board Crystal Oscillator of the Quasi-Zenith Satellite System

“…The first QZSS satellite is scheduled to be launched in 2008. QZSS consists of a multimission system that will provide a new integrated service platform for mobile devices based on audio-video communications, data broadcasting, and a positioning service [1,2].…”

“…In fact, conceptually made to work together with the present American GPS, the QZSS will provide higher precision positioning than the current GPS through the provision of compensating information (augmentation service). Moreover, since QZSS generates a GPS-compatible positioning signal (L1, L2 and L5), it will effectively become part of the GPS constellations, and it will improve the dilution of precision (DOP) throughout the East and South East Asia and Oceania [2]. Positioning satellite visibility is expected to improve, especially in highly populated areas where high-rise buildings easily limit it.…”

“…By contrast, the Japanese QZSS has a wholly different orbit system and different service aims [2]. First of all, being made for civil use, it does not have the same military requirements as GPS.…”