Galileo GIOVE-A Broadcast E5 Codes and their Application to Acquisition and Tracking

摘要

In this paper, we decode the PRN codes of the E5a and E5b signals broadcast by the Galileo GIOVE-A test satellite. The Galileo E5 band overlaps with Distance Measuring Equipment (DME) and Tactical Air Navigation (TACAN) bands. These navigation systems emit high-power pulses, causing severe interference to E5 signals and thus challenging the decoding process. We apply the 1.8 meter dish of the Stanford GNSS Monitor System to receive the satellite signals. The received data are processed in a chain of signal conditioning, Doppler wipeoff, secondary code wipeoff, code sequence demodulation, and code generator derivation. rnTwo primary code sequences are revealed in each frequency band, E5a-I, E5a-Q, E5b-I, and E5b-Q. The E5 signals have a chip rate of 10.23 Mbps. All four primary codes have a period of 1msec with 10230 bits and are modulated by secondary codes. The secondary code of E5a-I has 20 bits and that of E5b-I has 4 bits. The secondary codes of E5a-Q and E5b-Q are both 100 bits.