A Usrp - Based Flexible Gnss Signal Recording and Playback System : Performance Evaluation and Study

A USRP-BASED FLEXIBLE GNSS SIGNAL RECORDING AND PLAYBACK SYSTEM: PERFORMANCE EVALUATION AND STUDY by Ruihui Di Global Navigation Satellite Systems (GNSS) signals are often subjected to both manmade and natural interferences such as RF jamming, ionosphere scintillation, multipath, and signal anomaly. In order to achieve desired navigation application performances, advanced receiver processing or multi-sensor integration algorithms must be developed to mitigate these interferences. A flexible multi-frequency multi-constellation GNSS signal generator is an important enabler of robust GNSS receiver research and development. There is a growing number of companies that offer high end GNSS signal simulators or generators. These high end signal simulators or generators, however, are expensive and can be cumbersome. This thesis presents a reconfigurable wideband multi-frequency multi-constellation GNSS signal recording and playback system based on the Universal Software Radio Peripheral (USRP) N210 model. The USRP-N210 based recording and playback system is low cost, portable, and can be reconfigured to record and transmit the entire family of GNSS signals when paired with appropriate RFX daughter boards and controlled by an external low phase noise oscillator. The source of the signal can be pre-recorded digital samples obtained from other RF front ends or arbitrary waveform samples generated using MATLAB programs. An adjustable low noise signal amplifier mounted between the USRP-N210 output and the transmitting antenna was used to control the transmitted power of the signal. A spectrum analyzer was used to monitor the transmitted signal. The GPS L1, L2, L5, and GLONASS L1 and L2 signals were recorded and re-transmitted using the multi-GNSS signal recording and playback system. The receiver output and the transmitted signal are processed by both a NovAtel OEM receiver and software receivers and the results are compared with the original signal parameters to demonstrate the accuracy of the playback system. A USRP-BASED FLEXIBLE GNSS SIGNAL RECORDING AND PLAYBACK SYSTEM: PERFORMANCE EVALUATION AND STUDY