To meet the increasing demand for improved positioning performance and radio frequency compatibility of Global Navigation Satellite System (GNSS), next-generation navigation signals have been planned and being deployed. New signal modulation design for next-generation of GNSS must offer improved performance and the opportunity for spectrum compatible with existing and planned signals. This paper presents a class of particularly attractive modulations called Faded Harmonics subcarrier (FHS) modulations, and demonstrates their essential characteristics and performance for GNSS. Firstly, the principle of FHS modulation is first described. Then, the general mathematical model and the power spectral density of FHS modulations are derived. The FHS modulations present important characteristics for GNSS and provide superior performance with regards to specific secondary lobe suppression when compared to other BOC modulations. Finally, examples are presented to illustrate the construction and performance of Faded Harmonics subcarrier modulations for GNSS including spectra and correlation characteristics, code tracking, multipath and spectral separation performance. FHS modulations can provide potential opportunities for GNSS modernization and construction.

Keywords: satellite navigation, signal design, faded harmonics modulation, signal performance