Design Of Signal Tracking Module In GNSS-R Ocean Reflection Receiver

As a rising remote sensing technology, GNSS-R mainly relies on the signal source supplied by GNSS satellite. By installing GNSS-R receiver on the airborne or spaceborne platform to receive direct signals from the satellite, and signals reflected from the ocean , then processing the two kinds of signal separately, it can realize the detection and refutation of various global physical parameters in ocean environment. In contrast to traditional remote sensing technologies, this technology could get higher resolving capability of time and space, and there's no requirement of sole transmitter. Meanwhile, there are abundant signal sources, and the receiver is simpler and more portable, with stronger immediacy. This paper gives design proposal of signal tracking module of GNSS-R ocean reflection receiver on the basis of DSP + FPGA architecture with reference to practical research program.This thesis first introduces the current situation of GNSS-R technology research ,with the GPS system as an example, and analyzes the traits of each system's signal in GNSS. As to the GNSS-R ocean reflection receiver implementing the combination of hardware and software in this paper, the whole system includes the direction channel and reflection channel. The former completes the seizure, tracking, telegraph text acquisition by receiving direct signal from satellite through RHCP antenna; while the latter receives the reflected signal from the ocean's surface through LHCP antenna and manages to get the power curve of different code phase delay. As to the direction channel, this paper puts focus on pseudo code tracking proposal of making use of DDLL combined with carrier assistant technology on the basis of the research findings home and abroad. Considering the receiver's high dynamic circumstance and handling property requirement, this thesis discusses the carrier tracking proposal with the combination of FLL and PLL and completes the software emulation of the system's tracking plan in Matlab, after that, tests the plan's tracking performance by the emulation implements the receiver's tracking module by FPGA; while as for the reflection channel, this thesis posts the tracking plans of pseudo code phase delay and carrier frequency movement, and makes the accumulation and calculation after the stripping of pseudo code and carrier. The calculation result could complete different power curves. The designed tracking module finally can send the direct and reflected channels'tracking results to the host computer; meanwhile, the design plan could implement the parallel arithmetic of multisystem and multichannel , and puts forward the concrete method of communicating with the receiver's other modules.