M.S. Yarlykov

Modulating functions of an elementary AltBOC signals, a complete AltBOC signals with a non constant envelope and a complete AltBOC signals with a constant envelope are outlined. The elementary AltBOC signal can be composed of two pseudorandom code sequences (two components). If there are two components there is no pilot signal. If pilot components are introduced, four pseudorandom code sequences are needed. The complete AltBOC signals with a non constant envelope can be composed four pseudorandom code sequences (four components). In such AltBOC signal expression it is necessary to add four terms (product signals) to meet the requirement for a constant envelope. The complete AltBOC signals with a constant envelope can be composed eight components. The essential spectral properties of the AltBOC signals for next-generation of satellite radio navigation systems (in particular, the Galileo system) are considered. The analytical expressions of the spectrum functions and the power spectrum densities of modulating function single period of such AltBOC signals have been presented for various values of the multiplicity coefficient of meander pulses. Power spectrum densities and cross power spectrum of modulating function single symbol of AltBOC signals are plotted for the following types of AltBOC modulation: AltBOC(10,10), AltBOC(15,10), AltBOC(20,10) and AltBOC(25,10). A particular attention is made on the AltBOC(15, 10) signal which is candidate for Galileo E5a/E5b frequency band. AltBOC(15, 10) is a wideband signal that is transmitted at 1191.795MHz. It has code rate of 10.23 MHz and a meander (subcarrier) frequency of 15.345 MHz.