GNSS Reflected Signal Receiving And Processing Methods

Recently the use of GNSS reflected signals as opportunistic bi-static radar signals has become increasingly popular in the microwave remote sensing method. Using the reflected signals of GNSS satellite signals through the ocean or land reflection surface, it can be carried out remote sensing, retrieval and detection of sea surface wind field, humidity, salinity, forest cover and so on.In this paper the theory of GNSS reflected signal receiving and processing is described. It focuses on FPGA reflected signal correlator and DSP processor whice are designed according to requirements of the reflected signal receiving and processing system, including design and simulation of each sub-module, direct signal and reflected signal processing of processor. The Innovative work and the main achievements are as follows:1. In the correlation's resolution, the resolution option module and mode selection module are designed. According to the different needs of physical retrieval, it can achieve outputting of different resolution's correlation and power. 2. In the reflected signal processing, the fast demodulator and correlator are designed. The carrier demodulation and data correlation's multiplications whice use in traditional reflected signal processing are replaced. Through use of fast demodulator and correlator, depletion of the chip logic resources is reduced, so that receiver machine's extension is more flexible.3. In the C/A code generation of the reflected signal processing, the delay C/A code generator is designed. Not need to consider the using height of the receiver, with the aid of the DSP processor, it can produce the C/A code whice the reflection channel requires and be more suitable for airborne and satellite receiver.