Complete composite binary offset carrier modulated signals and their correlation function

Abstract

The formation and structure of complete composite binary offset carrier (CBOC) modulated signals are analyzed as applied to the new-generation satellite radio navigation systems (SRNSs) (in particular, the European Galileo and, presumably, Chinese BeiDou/Compass systems). The block diagram of the CBOC-signal satellite transmitter based on the coherent adaptive subcarrier modulation (CASM) algorithm is discussed. Analytical expressions for the correlation functions (CFs) characterizing the single elements of the modulating function (MF) of CBOC signals are derived at arbitrary fractional coefficients. The CFs of the single elements of the MFs of CBOC signals are represented graphically and their properties are discussed. The Fourier transforms of CFs are used to calculate the energy spectra (power spectral densities) of the single elements of the MFs of CBOC signals. CF features and the energy spectra of CBOC signals are analyzed using signals with CBOC(6, 1, a 2/11) modulation, which are typical of the European Galileo and Chinese BeiDou/Compass systems at the carrier frequency f car = 1575.42 MHz and the fractional coefficient a 2 = 1.