Earth Rotation Parameters Derived from BDS-3 New Signals B1C/B2a Dual-Frequency Combination Observations
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe paper titled "Earth rotation parameters derived from BDS-3 new signals 2 B1C/B2a dual-frequency combination observations" offers a unique and insightful investigation into the utilization of BDS-3's new signals for deriving Earth rotation parameters. The authors demonstrate a thorough understanding of the subject matter and present a well-structured analysis of the dual-frequency combination observations.
The paper offers valuable insights into the potential of BDS-3's signals in precision measurements of Earth's rotation. The results presented are convincing and contribute significantly to the field of geodesy and satellite navigation.
However, I suggest that the authors consider including a more detailed discussion on the limitations and challenges associated with the use of BDS-3 B1C/B2a signals for such measurements. This would provide a more comprehensive understanding of the study's scope.
Overall, the paper represents a significant contribution to the field and is worthy of publication. I am pleased to recommend its acceptance, subject to the authors' consideration of the above-mentioned suggestion.
Comments on the Quality of English LanguageMinor editing of English language required
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsComments:
In this manuscript, authors evaluate the performance of ERP estimation from B1I/B3I and B1C/B2a combination, aiming to find the best dual-frequency combination of BDS-3 ERP estimates for the future new ITRF definition with the consideration of BDS-3. Since the orbits and ERP are estimated at the same time, the quality of orbits can also reflect the performance of ERP estimates. The authors use satellite laser ranging (SLR) validating the orbits of 22 BDS-3 MEO satellites from B1I/B3I and B1C/B2a observations. The results demonstrate the excellent signal quality for the BDS-3 B1C/B2a and its superiority in the ERP estimation when comparing with the B1IB3I combination.
The manuscript is well conceived and presented, the results are clearly presented, the conclusions are well demonstrated and this work is valuable for the future new ITRF definition with the consideration of BDS-3. However, the minor changes are necessary for the manuscript to adapt to the high-quality standards of the remote sensing journal.
1. In figure1, the number of selected stations should also be written in the figure title.
2. "B1I/B3I combination and B1C/B2a combination" can simply be replaced by "B1I/B3I and B1C/B2a combinations" at line 15, line 200, line 210, line 213 and in other places of this paper.
3. From line 121 to 123, the description should be “The Datum definition achieved by using IGS20 core stations with minimal constraints including NNR and NNT to align with IGS20”.
4. Line 128: the description should be “GNSS technology could not directly estimate the UT1-UTC parameter”.
5. Line 149: the description should use “Figure 2 illustrates”.
6. Line 183: the description should be “Ambiguity resolution is a crucial step in achieving GNSS data processing with phase observations”.
7. Line 188: the abbreviation “HMW” should also write it full name.
8. In figure4, the title of X axis should be "DOY" instead of "Days".
9. Line 278: the abbreviation CODE MGEX (COM) should appear at line 276.
10. In Section 6.2, the authors compared ERP with the external products, could you explain why you choose IERS 20C04 products instead of IGS final products?
Comments on the Quality of English LanguageI have no comment.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe purpose of this research is to evaluate the optimal dual-frequency combination for BDS-3 ERP estimates to improve the global reference frame and GNSS performance. It specifically assesses the performance of ERP estimation using BDS-3 B1I/B3I and B1C/B2a combinations and validates the superiority of the B1C/B2a combination over B1I/B3I through comprehensive signal quality, orbit precision, and ERP accuracy analysis.
The authors are recommended to include a brief explanation on the tropospheric model used in this study. Ionospheric effect has been wisely cancelled by employing ionosphere-free models. But the troposphere model requires a quick elaboration since the references to previous work provided, e.g., https://doi.org/10.1029/97JB01739 and https://doi.org/10.1007/s00190-017-1066-2, are too general, and the model and its inputs and variables need to be specifically mentioned.
The authors are recommended to the modern applications of GNSS in the remote sensing area, such as GNSS-R. The authors may refer to https://doi.org/10.1109/JSTARS.2023.3330745, which is a recent publication in this field.
In Table 3, the authors are recommended to include other statistical analysis, such as STD and mean error, for SNR values since their variations might be significant.
Author Response
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Author Response File: Author Response.pdf
