ACCOUNTING FOR TIMING BIASES BETWEEN GPS, MODERNIZED GPS, AND GALILEO SIGNALS

GPS timing and navigation user solutions are based on pseudorange measurements made by correlating user receiver-generated replica signals with the signals broadcast by the GPS satellites. Any bias resulting from this correlation process within the user receiver tends to be common across all receiver channels when the signal characteristics are identical (code type, modulation type, and bandwidth). Such common biases will cancel in the user navigation solution and appear as a fixed bias for timing solutions. New GPS signals and the future addition of the Galileo system are somewhat different from the legacy signals broadcast by GPS today and new ways of accounting for biases will be needed. This paper will quantify timing biases between the different legacy and modernized GPS and Galileo signals broadcast on L1 and their dependencies on factors like user receiver filter bandwidth, filter transfer function, and delay-locked loop (DLL) correlator spacing.