Optimal path-control for dual-frequency overlay GNSS receivers

This paper presents a general overlay based front-end architecture that enables the joint reception of two signals broadcast in separate frequency bands, sharing just one common baseband stage. The consequences of this overlay in terms of signal quality are analyzed and it is shown that the noise floor superposition results in non-negligible signal degradations. However, it is also demonstrated that these degradations can be minimized by judiciously setting the relative gain between the two signal paths. As an illustration, the analytical optimal path- control expression to combine overlayed signals in an ionospheric- free pseudorange is derived for both Cramer-Rao Lower Bound and practical code tracking parameters.