Galileo system uses direct sequence/spread spectrum (DS/SS) as its modulation method. Single delta delay lock loop (Delta-DLL), where Delta is sample duration between early and late correlation values, has been widely used for code tracking in DS/SS systems. When the Delta-DLL is used for code tracking in ideal environments, code tracking bias does not arise because the symmetry of the correlation function is not destroyed. However, in multipath (MP) environments, a large code tracking bias arises owing to the asymmetrical correlation function. An MP signal always has a propagation delay time after that of the line of sight signal. Thus, correlation values in the advanced offset region are less distorted than those in the delay offset region. From this observation, we propose an effective tracking bias compensation scheme for the Galileo E1 open service signal.
[1]
Michael S. Braasch,et al.
Performance comparison of multipath mitigating receiver architectures
,
2001,
2001 IEEE Aerospace Conference Proceedings (Cat. No.01TH8542).
[2]
Guenter W. Hein,et al.
Criteria for GNSS Multipath Performance Assessment
,
2005
.
[3]
Per Enge,et al.
Multipath mitigation for narrowband receivers
,
2000,
IEEE 2000. Position Location and Navigation Symposium (Cat. No.00CH37062).
[4]
Johann Furthner,et al.
GIOVE-A initial signal analysis
,
2006
.
[5]
Bernd Eissfeller,et al.
Multipath Performance Analysis for Future GNSS Signals
,
2004
.