Research on multi-system software GNSS receiver of micro-satellite

Applied Technology in "GNSS if Signal Acquisition System" and Software Receiver Design

“…The internal circuit of FPGA [1] was designed for the coordination between CY7C68013A interface chip and the FPGA, the key lies in the cache and the logic control functions to ensure that the data can be cached by the FIFO in FPGA during a certain period of time when the PC software can't read data for some reasons, which can effectively improve the overall bandwidth of the data acquisition system. Within the FPGA, the reference clock drives 8 samples of IF data string to transfer and combined into a 16 bits data, then the data enter into the custom FIFO caching, FIFO depth is large enough to meet the transmission requirements, and the half-full flag was set to detect whether the FIFO is overflowed or not during data acquisition process.…”

“…Compared with the traditional technology of hardware receiver, the software receiver has many advantages, in recent years it has become one of the most important development trend in the field of satellite navigation [1] . Intermediate frequency signal is the data source of software receiver, the access method including intermediate frequency signal simulation and real-time acquisition.…”

“…Intermediate frequency signal is the data source of software receiver, the access method including intermediate frequency signal simulation and real-time acquisition. USB2.0 is currently the mainstream high-speed serial interface with high transmission speed, supporting plug and play features and so on [1,2] , which is able to meet the needs of high-speed real-time intermediate frequency signal acquisition; Cypress company's mainstream USB2.0 interface chip CY7C68013A is being widely used; In terms of digital circuit design, FPGA has big flexibility, its working frequency can completely satisfy the requirements of general intermediate frequency signal acquisition; Linux operating system stability and the reliability is high, to which more and more close attention is being paid, the C/C++ code which is linked and compiled by Linux internal GCC compiler has higher operation efficiency [3] . More importantly, under the condition of the same hardware, Linux can achieve bigger data transmission bandwidth than Windows.…”