PC, 타이머 카드와 USRP 보드를 이용한 GNSS/INS 시뮬레이터의 시각동기 시스템 설계

Abstract

The purpose of the Global Navigation Satellite System/Inertial Navigation System (GNSS/INS) simulator is to provide GNSS signals and iInertial mMeasurement uUnit (IMU) data in a real environment. If the GNSS/INS simulator provides unsynchronized GNSS signals and IMU data, the performance of the GNSS/INS integrated navigation system cannot be accurately evaluated. In this paper, a design method of a time synchronization system for the GNSS/INS simulator is proposed using a PC, timer card, and Universal Software Radio Peripheral (USRP) board. The USRP board up-converts the GNSS IF data into an RF signal and provides the Pulse Per Second (PPS) signal. The timer card generates an interrupt request signal to the PC at the same rate as the IMU data from the PPS signal of the USRP board. The PC provides the GNSS IF signal and IMU data and synchronizes the time of the IMU data to the GNSS IF data based on the interrupt request signal. In order to show demonstrate the usefulness of the proposed method, the time synchronization results of IMU data are checked along the GNSS signal in the GNSS/INS simulator, and the effect of the time synchronization of the GNSS/INS simulator on the navigation system is checkedevaluated. The experimental results show that the proposed time synchronization method generates the GNSS IF signals and IMU data very similar to that closely correspond with the real environment.