binary offset carrier modulation (BOC)
Insatellite navigation, navigation data is transmitted from the satellite using Binary Offset Carrier Modulation( BOC) or Binary PhaseShift Keying(BPSK).
BOC modulation works with two or more subcarriers, above and below the carrier frequency, which are modulated with different information. This modulation method allows several different signals to be transmitted simultaneously.
The subcarriers are generated by modulating the carrier signal with a rectangular offset signal and are available for modulation alternating with the modulation signals. In Galileo, the BOC modulation is used for the transmission of the two E5 signals E5a and E5b.