GNSS卫星信号模拟器码和载波NCO研究与实现

NCO是卫星信号模拟器中频信号处理的关键部分。介绍了GNSS卫星信号模拟器码NCO和载波NCO的原理及作用,建立DDS模型,确定基本参数并根据参数设计了码NCO和载波NCO基本结构。给出了码NCO和载波NCO的实现过程,利用verilog在Xilinx’ISE11.2和modelsim6.5中完成载波NCO和码NCO的设计和仿真,在FPGA中进行了实现,并给出仿真波形和信号频谱图。本码NCO和载波NCO模块已应用于某型GNSS模拟器样机,通过程序仿真与样机测试,证明本码NCO和载波NCO模块性能满足GNSS卫星信号模拟器系统需求。

Rasearch and implementation of code and carrier NCO in GNSS signal simulator

NCO is the key part of intermediate frequency signal processing in GNSS signal simulator .The principle and function of the code NCO and carrier NCO in GNSS signal simulator are described. A model for DDS is established. The basic configuration of code NCO and carrier NCO was designed. The implementation process of code NCO and carrier NCO was given. With the Xilinx’ISE11.2 and ModelSim6.5 development tools and FPGA using verilog, the design and simulation of the code NCO and the carrier NCO is implemented, and the emulator wave and signal frequency spectrum was given. The code NCO and the carrier NCO has been in application in one prototype of GNSS simulator model. By the procedure simulating and system testing, it is shown that the module specifications of the code NCO and carrier NCO meet the requirement of GNSS signal simulator.