摘要：How will the Open Service Galileo signal in space change the acquisition process in GNSS receivers?
A: The Galileo signal in space (SiS) for the Open Service (OS) essentially differs from the GPS C/A-code by its use of the binary offset carrier (BOC) modulation and the adoption of longer spreading codes. Moreover, two different channels have been allocated for the OS: the data and the pilot channels. The former carries the navigation message whereas the latter is data-free.
The pilot channel is characterized by a secondary code that modulates the primary spreading sequence, producing a tiered code with a period of 100 milliseconds. The bit-rate of the data channel is 250 sps (symbols per second) against the 50 sps of the GPS C/A-code. A GNSS receiver can perform acquisition of the pilot and data channels separately, and the results of the two processes can be non-coherently combined in order to exploit the fact that the two signals experience the same code delay and Doppler frequency.
