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针对高动态、低信噪比的接收信号,首先对整个多普勒频率范围进行分段,并在每一段内利用本地产生的带有多普勒频率变化率的复信号来抵消接收信号中多普勒频率变化率的影响,然后在每一段内利用FFT(FastFourierTransform,快速傅里叶变换)进行载波频率并行捕获,从而同时完成载波多普勒频率及其变化率的初步估计。利用载波多普勒频率及其变化率估计信息辅助锁频环快速入锁,进而利用锁频环辅助三阶锁相环完成载波信号的锁频锁相跟踪。使用这种方法,可以快速获取信号的多普勒频率及其变化率信息,并且在极短时间内完成载波的稳定跟踪,使接收设备具备快速捕获跟踪大动态弱信号的能力。 相似文献
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《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2023,71(3):1525-1542
Global Navigation Satellite System Interferometric Reflectometry (GNSS-IR) technology provides a new means of snow depth detection. Multi-satellite and multi-Signal-to-Noise Ratio (SNR) provide more data for daily high-precision snow depth retrieval, but also face the problem of data fusion and effective utilization. Therefore, this study proposes a robust estimation algorithm based on multi-satellite and multi-SNR fusion applied to the observations of a GNSS station in Alaska. This study uses four solutions (Savg, Smed, SRE_avg and SRE_med) to carry out multi-system fusion snow depth inversion and precision comparison research. The Savg has more obvious disadvantages, which is not suitable for snow depth assessment. The SRE_avg and SRE_med have better snow depth retrieval effects in the snowy periods. The correlation coefficient (R), root mean square error (RMSE) and mean error (ME) of the calculated snow depth using the robust estimation algorithm with respect to the nearest in-situ measurements reached 0.759, 3.7 cm and ?1.4 cm, respectively. Compared with the Smed, the R is increased by 2.0 %, the RMSE corresponds to an improvement of 2.6 %. Moreover, the ME of the snow depth retrievals, as an indicator of the measurement bias, has significantly decreased by 6.7 %. The result also shows that the snow depth inversion by the robust estimation algorithm is more consistent with the in-situ measurements, further extending and advancing the optimal algorithm for snow depth retrieval. 相似文献
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首先针对TLE更新不及时、轨道递推准确性低的问题,提出低成本卫星测控系统(LCTTC)采用卫星GPS实测数据修正站心坐标系下目标轨道方法,提高跟踪精度;其次利用接收机的RSSI功能,给出了远程获取无人值守LCTTC灵敏度、评估其性能的方法,以及获取信噪比、发射功率等状态信息的方法,对卫星实时任务过程进行监测和异常诊断,减少了故障排查时间。 相似文献