An Improved Doppler-Aided Smoothing Code Algorithm for BeiDou-2/BeiDou-3 un-Geostationary Earth Orbit Satellites in Consideration of Satellite Code Bias

Round 1

Reviewer 1 Report

The manuscript of “An improved Doppler-aided smoothing code algorithm for BDS-2/BDS-3 un-GEO satellites in consideration of satellite code bias” mainly develop an optimal DSC approach with the principle of minimum variance based on the Hatch-filter. Overall, the paper is well written and good structure, the results are credible. Minor revision is need to before I recommend this research for publication in RS.

1) Maybe add a flowchart to better improve the readability of the manuscript.

2) The Formula size is inconsistent, please revise.

Author Response

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Reviewer 2 Report

This paper focuses on the topic of Doppler-aided smoothing code method for BDS un-GEO satellites. In addition to addressing the measurement errors, the authors proposed a polynomial segment fitting algorithm as a function of elevation angles to mitigate the SCB effect.

Overall, this paper is well-structured and presents valuable insights. I recommend that the paper be published, but some improvements and clarifications should be made.

 

(1)    B1 frequency are more affected by the SCB than that on the B3 frequency. What would be the reasons?

(2)    "It can be seen that the variance of DSC is positive relevance with SWF, but unlike CSC, it is not monotonously decrease with increasing SWF, which means that the size of smoothing window (SW) for DSC should be limited" I think this is not clear at all. This is an important assumption and should be clarified.

(3)    The description of figure 2 needs to be clarified. Furthermore, I need to see the importance of this analysis in the following paragraphs.

(4)    What is the reason for noise amplification together with an increase in sampling interval? It suggests some temporal correlation. Please discuss.

(5)    Figure 8, Please discuss why RDSC is very effective for a narrow band of sampling interval only.

Author Response

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Reviewer 3 Report

The results do not support the conclusions. No results in challenging environment and high dynamic scenario.

Comments for author File: Comments.pdf

Author Response

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Round 2

Reviewer 3 Report

Doppler is an instantaneous measurement， Eq. 23 may not be correct in high-dynamic situation.  for example, the antenna may be static at epoch k and k+1, but it moves between epoch k and k+1. This is why I asked for high-dynamic results.

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.docx