Meta-Signal Inspired Quad-Frequency GNSS Measurement Combinations

A global navigation satellite system (GNSS) receiver operates at different levels: at the front-end level, where radio frequency (RF) signals are converted into digital samples, in the signal processing domain, where signals are converted into raw observations and at the measurement level where observations are combined and used to generate the final position solution. The measurement and signal processing domains are strictly related and a concept arising in one domain often has its equivalent in the other. In this respect, the GNSS meta-signal paradigm can also be implemented in the measurement domain. The general meta-signal paradigm recently introduced for multi-frequency GNSS signals is used here to define and characterize quad-frequency GNSS measurement combinations, which generalize to four dimensions classical narrow and wide lane combinations. Moreover, a generalization of the Hatch-Melburne-Wübbena (HMW) code-carrier combination with four signals is also provided. Different options originating from the meta-signal paradigm are derived. Theoretical results are complemented by an experimental analysis conducted using data collected from two Septentrio PolaRx5S multi-frequency, multi-constellation receivers set up in a zero-baseline configuration. This allows the analysis of uncombined measurements, single-differences and dual-differences. The analysis shows the advantages and limitations of using these types of quad-frequency measurement combinations.