Quasi-Zenith Satellite System | EPFL Graph Search

The Quasi-Zenith Satellite System (QZSS), also known as Michibiki, is a four-satellite regional satellite navigation system and a satellite-based augmentation system developed by the Japanese government to enhance the United States-operated Global Positioning System (GPS) in the Asia-Oceania regions, with a focus on Japan. The goal of QZSS is to provide highly precise and stable positioning services in the Asia-Oceania region, compatible with GPS. Four-satellite QZSS services were available on a trial basis as of 12 January 2018, and officially started on 1 November 2018. A satellite navigation system independent of GPS is planned for 2023 with seven satellites. In May 2023 it was announced that the system would expand to eleven satellites. History In 2002, the Japanese government authorized the development of QZSS, as a three-satellite regional time transfer system and a satellite-based augmentation system for the United States operated Global Positioning System (GPS) t

Design of a GPS and Galileo Multi-Frequency Front-End

Cyril Botteron, Frédéric Chastellain, Pierre-André Farine, Enrique Rivera Parada, Youssef Tawk

GNSS platforms such as the American Global Positioning System (GPS) or the Russian GLONASS system are being continuously updated with new satellites offering new signals, new frequencies and new functionalities. Moreover, new GNSS systems such as the European Union’s Galileo system or the Japan’s Quasi-Zenith Satellite System (QZSS) are currently being developed and planned to be in function within a couple of years. Taking advantage of these new signals requires the use of a multi-frequency Radio-Frequency (RF) Front-End (FE). In this paper, we highlight the design of such a FE based on a sub-sampling architecture. Indeed, with the technology advances in the Integrated Circuits (IC) industry, and more particularly the availability of GHz bandwidth analog-to-digital converters (ADC), this is one of the most attractive ways to achieve a multi-frequency FE. While a sub-sampling architecture has already been presented in some other publications [1], [2], we present a methodology that takes into account the effects of the filters characteristics and out-of-band noise. As a practical example, we apply our methodology to the design of a multi-frequency RF FE for the simultaneous acquisition of the GPS L1C; L2C; L5, and Galileo E1b;c; E5a;b signals.

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Dual-frequency RF front-ends for GNSS receivers

Frédéric Chastellain

The Global Positioning System (GPS) is a trilateration system which allows to compute the position of a receiver from the time the signals need to propagate from the satellites down to the receiver. Since the Selective Availability (SA) was turned off in 2000, the most important source of error is due to the variable delay experienced by the signals when traveling through the ionosphere. Today, the majority of GPS receivers use the L1C/A signal, the only civil signal currently transmitted by a full constellation of satellites, to compute their positions. The United States' GPS is actually only one of several Global Navigation Satellite Systems (GNSS) under development, such as the european Galileo or the Japanese Quasi-Zenith Satellite System (QZSS). In the years to come, the constellations of these new GNSS will be fully deployed, providing new modernized signals. The GPS is actually also being modernized and will provide two new civil signals, the first in the L2 band (1227.6 MHz) and the second in the L5 band (1176.45 MHz), as well as an improved version of the L1C/A signal in the L1 band (1575.42 MHz). The first fully available new civil signal will certainly be the GPS civil signal in the L2 band called the L2C signal. The availability of two civil signals in two different bands will give the opportunity to correct the ionospheric error to a great extent! However, receiving two signals located in different bands will add complexity in the receiver, particularly in the radio-frequency (RF) front-end. This is a major issue since, for the mass market, improved performances do usually not justify a higher power consumption and cost. As a consequence, the first objective of this thesis was to design a low-power dual-frequency RF front-end architecture for the L1C/A and L2C signals that could be integrated using standard CMOS technology and which would have a power consumption and performances comparable with that of state-of-the-art single-frequency GPS RF front-ends. Dual-frequency correction of the ionospheric error will also allow to improve the performances of another application of GPS called GPS timing. Indeed, the GPS provides the most precise time reference globally available anywhere on earth! As a consequence, an attractive solution to synchronize telecommunication networks consists to use the time reference provided by the GPS. However, the accuracy provided by single-frequency GPS receiver will soon not be sufficient anymore to be compliant with upcoming telecommunication standards. For this reason, the second objective of this thesis was the development of a dual-frequency RF front-end for an L1C/A + L2C GPS receiver for timing applications.

EPFL2010

Dual-frequency RF front-ends for GNSS receivers

Frédéric Chastellain

EPFL2010