Global Positioning System Reference
In-Depth Information
The purpose of code tracking is to estimate the travel time
τ
and is done by
means of a
delay lock loop
(DLL). For a coherent DLL we have
0.
To demodulate the navigation data, a carrier wave replica must be generated.
To track a carrier wave signal, a
phase lock loop
(PLL) often is used.
θ
=
A final remark.
This chapter exposed most of the material relevant to code the
L1 OS Galileo signal. However, GPS is also under continuous development—
a very fortunate situation for the user. The planned civilian L5 GPS signal is
described in ICD-GPS-705 (2002). Comparing the present chapter, which is based
on Anonymous (2005), with ICD-GPS-200 (1991) you realize that the European
and American satellite navigation communities are each using their own lingos.
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