| Citation: | FAN Mengwen, ZHANG Bo, WANG Fenget al. Semi-codeless based P(Y) code autocorrelation GNSS-R sea surface altimetry method[J]. Journal of Beijing University of Aeronautics and Astronautics, 2019, 45(2): 398-404. doi: 10.13700/j.bh.1001-5965.2018.0294(in Chinese) | 
In this paper, the semi-codeless based P(Y) code autocorrelation sea surface altimetry method was studied due to the fact that the conventional GPS C/A code delay altimetry method is less precise, and that the signal-to-noise ratio of delay waveform in interference altimetry method is low. First, the height measurement accuracy of the C/A code and P(Y) code was compared and analyzed through theoretical model for describing the height measurement accuracy. Then, the architecture of semi-codeless based P(Y) code autocorrelation processing for L1 and L2 dual-frequency reflected signals was described. Meanwhile, the altimetry model and dual-frequency ionospheric time-delay error correction methods are discussed. Finally, using simulated L1 and L2 reflection signals, the measurement accuracy is compared and analyzed regarding the proposed method, C/A code autocorrelation method and signal cross-correlation method. The results show that the accuracy of the proposed method is 3.97 times and 1.47 times higher than that of the C/A code autocorrelation method and signal cross-correlation method, respectively.
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