Global Positioning System Reference
In-Depth Information
Galileo Signal
The Galileo system offers several services, a few are free of charge and the rest
are commercial. In this topic we deal only with the L1 OS signal (OS for open
service).
The L1 OS signal alone is expected to guarantee a horizontal accuracy better
than 15 m, a vertical accuracy better than 35 m, a velocity accuracy better than
50 cm/s, and a timing accuracy better than 100 ns.
The augmentation from a single-frequency to a dual-frequency Galileo receiver
naturally includes the E5a signal. For a dual frequency receiver the corresponding
accuracies are 7 m, 15 m, 20 cm/s, and 100 ns.
All Galileo satellites use the same frequency bands and make use of code divi-
sion multiple access (CDMA) technique. Spread spectrum signals will be trans-
mitted including different ranging codes per signal, per frequency, and per satel-
lite. All signals are transmitted in a right-hand circular polarization.
In this chapter we rely on Anonymous (2005). For more details the reader is
referred to this document; also note that all information is to be considered pre-
liminary.
3.1
Signal Theoretical Considerations
Today when designing the Galileo signals the situation is very different from the
days when the GPS signals were designed. Nowadays applications with difficult
signal reception set the specifications for GNSS; the receiver may be used in the
woods or indoors. This puts the most demanding efforts on the signal design.
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