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首页> 外文会议>Proceedings of the national technical meeting : "Vision 2010: Present and future" >Impact of Ionospheric Scintillation on GPS/WAAS System and its Mitigation Techniques
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Impact of Ionospheric Scintillation on GPS/WAAS System and its Mitigation Techniques

机译：电离层闪烁对GPS / WAAS系统的影响及其缓解技术

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摘要

Small-scale variations in ionospheric electron density result in amplitude and phase scintillation (rapid variations) of the received GPS signal. It is known that these effects get more severe during times of peak solar activity and in equatorial and polar regions. Possible effects of this phenomenon on the overall performance will appear via degraded measurement accuracy obtained by the user receiver and by the reference receivers in case of Wide Area Augmentation systems such as FAA WAAS. Further effects are in terms of frequent receiver loss of lock and longer acquisition times.rnThis paper presents simulation results on the degradation of receiver performance due to amplitude and phase scintillation. It is shown that under Rayleigh fading conditions representing strong scintillation, there is a performance degradation of up to about 6-7 dB due to amplitude scintillation. The paper also presents adaptive and optimum smoothing techniques to compensate for fading and shows that the proposed techniques more than compensate for the degradation due to fading. Moreover, even when there is nornfading, the smoothing technique can be applied to improve the system performance by about 6 dB as the required smoother delay is only a small fraction of 1 sec and can be easily compensated for in most GPS applications.rnUnder relatively high phase scintillation condition, the possible performance loss is even more severe, i.e. 10-5 dB possible loss. For this case a multistage estimator is presented. From simulation examples it is observed that a second estimation stage results in improvement of about 6.5 dB. If this method is combined with the smoother technique, the combined improvement due to both two-stage estimator and smoother may completely offset the scintillation impact.
机译：电离层电子密度的小范围变化会导致接收到的GPS信号出现幅度和相位闪烁（快速变化）。众所周知，在太阳活动高峰时以及在赤道和极地地区，这些影响会更加严重。在广域增强系统（例如FAA WAAS）的情况下，用户接收器和参考接收器获得的降低的测量精度会导致这种现象对整体性能的可能影响。进一步的影响包括接收机频繁失锁和更长的获取时间。本文介绍了由于幅度和相位闪烁而导致接收机性能下降的仿真结果。结果表明，在代表强闪烁的瑞利衰落条件下，由于幅度闪烁，性能会下降约6-7 dB。本文还提出了自适应和最佳平滑技术，以补偿衰落，并表明，所提出的技术不仅可以补偿由于衰落引起的劣化。此外，即使存在降噪现象，由于所需的平滑延迟仅为1秒的一小部分，并且可以在大多数GPS应用中轻松补偿，因此可以应用平滑技术将系统性能提高约6 dB。在相位闪烁条件下，可能的性能损失甚至更加严重，即10-5 dB的可能损失。对于这种情况，提出了一个多级估计器。从仿真示例中可以看出，第二个估计阶段可提高约6.5 dB。如果将此方法与平滑器技术结合使用，则由于两阶段估计器和平滑器的结合而产生的改进效果可能会完全抵消闪烁的影响。

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