基于AD9361射频捷变收发器的GPS伪卫星设计

为了搭建用于室内定位的伪卫星室内定位系统，设计了一个伪卫星用于发射模拟GPS卫星定位信号。从伪卫星的硬件结构的角度详细说明了该伪卫星的各部分硬件组成以及相应的功能。该伪卫星使用了AD9361射频捷变收发器将时钟小数分频、数模转换、信号调制、上变频融为一体，简化了伪卫星的硬件结构。介绍了该伪卫星生成的信号的具体结构，采用时分多址（Time Division Multiple Access，TDMA）技术使得接收机接收伪卫星信号时不会被阻塞。利用示波器、频谱仪和嵌入式逻辑信号分析仪Signal Tap对伪卫星进行测试，包括时钟频率、伪码、BPSK调制、TDMA技术等，结果表明伪卫星工作正常，其信号能被ublox正常接收，可以利用其进行下一步伪卫星组网用于室内定位。

Design of a GPS pseudolite based on AD9361 RF agile transceiver

To construct a pseudolite indoor positioning system,a pseudolite is designed to transmit a simulated GPS satellite positioning signal.Firstly,in terms of the hardware structure of the pseudolite,the hardware components and corresponding functions of each part of the pseudolite are explained in detail.The pseudolite utilizes the AD9361 RF agile transceiver to integrate functions of converting the clock fraction frequency division,digital-analog conversion,signal modulation and the frequency conversion,which simplifies the hardware structure of the pseudolite.Then,the specific structure of the signal generated by the pseudolite is introduced,and the implementation method of the time division multiple access(TDMA) technology in the pseudolite is also illustrated,which makes the receiver not be blocked when receiving pseudolite signals.Finally,the oscilloscope,spectrum analyzer and embedded logic signal analyzer Signal Tap software is used to test and verify each part of the pseudolite in detail,including clock frequency,pseudo-code,BPSK modulation,TDMA technology,etc.The result shows that the pseudolite works well,whose signal can be received by ublox normally.So it can be used to construct the pseudolite indoor positioning system.