With the development of satellite navigation technology,the user demands for the integrity of Global Navigation Satellite System(GNSS)have increased more and more.A ground-based monitoring system can hardly report an ...With the development of satellite navigation technology,the user demands for the integrity of Global Navigation Satellite System(GNSS)have increased more and more.A ground-based monitoring system can hardly report an alarm message to GNSS users during the valid alarming period due to the satellite-Earth propagation delay.It is beneficial to monitor abnormal events and report the corresponding alarms from orbit.Adopting this approach,which is an important feature for future GNSS integrity monitoring,the time needed to provide an alarm is shorter and the system integrity capability is strengthened.The BeiDou Navigation Satellite System(BDS)new generation satellites have the capabilities of satellite autonomous integrity monitoring(SAIM).This paper presents the technical scheme of SAIM,and proposes the integrity monitoring method of both navigation signals and the clocks onboard.The proposed method was verified through the onboard test on the BDS satellites.In addition,we analyzed the integrity telemetry data from the new generation of BDS satellite,including signal delay,power,carrier phase measurement,correlation peak,consistency of pseudo-code and carrier phase,clock phase and frequency step.The analysis results indicated that the quality of the data on orbit met the requirements,and SAIM could monitor effectively any abnormal change of satellite clocks and navigation signal,generate rapidly an alarm message,and transmit it to the user.The alarm time was less than 6 s through the message,and 2 s through non-standard code(NSC).Finally,we present future opportunities for improving the SAIM technology of BDS.展开更多
文摘在移除二进制偏移载波(Binary Offset Carrier,BOC)信号跟踪模糊的同时,为了保持BOC信号高的码跟踪精度,提出基于加权鉴别函数(Weighted Discriminator Function,WDF)的BOC信号无模糊跟踪方法。WDF使用非相干超前减滞后功率(Noncoherent Early Minus Late Power,NELP)鉴别器和子载波相位消除(Sub Carrier Phase Cancellation technique,SCPC)鉴别器,生成无误锁点的鉴别函数实现BOC信号跟踪。针对BOC(10,5)信号,仿真结果表明,相比于SCPC、基于伪相关函数的无模糊延迟锁定环(Pseudo correlation function based Unambiguous Delay Lock Loop,PUDLL)方法和对称脉冲模糊移除(Symmetrical Pulse Ambiguity Removing,SPAR)方法,所提WDF方法在码跟踪误差方面分别改善了2.5dB、5.5dB与8.3dB,多径误差分别降为60.4%、32.8%与38.0%。因此,WDF是一种有效的、高性能的BOC信号无模糊跟踪方法。
文摘With the development of satellite navigation technology,the user demands for the integrity of Global Navigation Satellite System(GNSS)have increased more and more.A ground-based monitoring system can hardly report an alarm message to GNSS users during the valid alarming period due to the satellite-Earth propagation delay.It is beneficial to monitor abnormal events and report the corresponding alarms from orbit.Adopting this approach,which is an important feature for future GNSS integrity monitoring,the time needed to provide an alarm is shorter and the system integrity capability is strengthened.The BeiDou Navigation Satellite System(BDS)new generation satellites have the capabilities of satellite autonomous integrity monitoring(SAIM).This paper presents the technical scheme of SAIM,and proposes the integrity monitoring method of both navigation signals and the clocks onboard.The proposed method was verified through the onboard test on the BDS satellites.In addition,we analyzed the integrity telemetry data from the new generation of BDS satellite,including signal delay,power,carrier phase measurement,correlation peak,consistency of pseudo-code and carrier phase,clock phase and frequency step.The analysis results indicated that the quality of the data on orbit met the requirements,and SAIM could monitor effectively any abnormal change of satellite clocks and navigation signal,generate rapidly an alarm message,and transmit it to the user.The alarm time was less than 6 s through the message,and 2 s through non-standard code(NSC).Finally,we present future opportunities for improving the SAIM technology of BDS.
