Evolution of Maritime GNSS and RNSS Performance Standards
Round 1
Reviewer 1 Report
General opinion:
This paper serves as a literature review of the International Maritime Organization GNSS and RNSS performance standards, including its policies, recommendations, guidelines, requirements and future concepts. It highlights the issues and weaknesses of such existing protocols while naming the integrity monitoring in maritime position sensors as the main issue. The paper then tries to propose solutions and recommendations to mitigate this problem.
The paper format aligns with RS standards and it can be interesting to many readers that are new to the domain of maritime GNSS. The authors’ literature review is well appreciated but the main contribution of the paper is weak. In most of the paper, the authors present background information and only approach the future concepts in the last sections, which should have taken the most significant space. The paper is also unnecessarily long and can be misleading in some of its sections (the IMO policy sections spans for 8 pages for example). In general, it was hard to follow the main goal of the paper. I appreciate that the paper provides a review and not a new method, but even as a review paper, it does not provide information that cannot be easily accessed or that holds new contributions to the domain except a few.
Therefore, in my opinion, the paper is not ready to be published in RS.
Thank you.
Author Response
Point 1: The main contribution of the paper is weak. In most of the paper, the authors present background information and only approach the future concepts in the last sections, which should have taken the most significant space.
Response 1: We appreciate the reviewer’s insightful and helpful comments on our manuscript. Regarding the concern 1 the presentation of future concepts has been expanded. Part of the text covering ongoing research on integrity algorithms has been moved from IMO policy section to the section 4. We have decided to keep the most of background information because in our opinion it is valuable and useful for a reader of a review paper. Such information allows a reader to form her / his own opinion on the IMO regulatory process.
Point 2: The paper is unnecessarily long and can be misleading in some of its sections (the IMO policy sections spans for 8 pages for example).
Response 2: The structure of the paper has been amended. The basic statistical formulae were moved to the appendix and the IMO policy section size was reduced.
Point 3: It was hard to follow the main goal of the paper. Even as a review paper, it does not provide information that cannot be easily accessed or that holds new contributions to the domain except a few.
Response 3: In the restructured paper the main goal of reviewing issues of existing International Maritime Organization recommendations, guidelines, requirements, performance standards, and future standards of GNSS should be more clear to follow.
Reviewer 2 Report
Well prepared educating review article which consist of 5 chapter namely;
1. Introduction
2. IMO GNSS Policy
3. IMO GNSS Performance Standards
4. Research and future development of maritime GNSS standards
6. Conclusions
Obviously there is a mistake. Either chapter 5 is missing or numbering should be corrected.
In my opinion, it would be better if the discussion given in conclusion, would be given in another chapter "discussion". Furthermore, I would suggest to present not only challenges but also deepen the potential solutions. As this is a review article, an academic method / based would not be expected from author for their solution but deepening their discussion will improve the quality of the manuscript.
There is also another possibility that presenting the challenges via SWOT analysis.
Author Response
Point 1: There is a mistake. Either chapter 5 is missing or numbering should be corrected.
Response 1: We appreciate the reviewer’s insightful and helpful comments on our manuscript. The structure of the paper has been amended and consecutive numbering of chapters fixed.
Point 2: It would be better if the discussion given in conclusion, would be given in another chapter “discussion”. Deepening discussion will improve the quality of the manuscript.
Response 2: The section “Discussion” has been added and its contents deepened. The conclusions have been shortened to the most significant ones.
Point 3: I would suggest to present not only challenges but also deepen the potential solutions. There is also another possibility of presenting the challenges via SWOT analysis.
Response 3: The potential solutions and SWOT analysis has been added to the discussion.
Reviewer 3 Report
1. Please delete Type of the Paper: in line 1
2. Keywords should be in alphabetical order
3. Abstract could be more explicit in what the paper is about.
4. Fig 2 source, please check all the Figures where there is no source information. Also, please an information for Tables.
The structure of the paper is a bit different than expected in template. Please go through the template and write some questions in chapter 1 needed to be answered in paper and then connect the research part with answers to questions. And connect all in the conclusion together with answering what are the future expectation.
Author Response
Point 1: The structure of the paper is a bit different than expected in template. Please go through the template and write some questions in chapter 1 needed to be answered in paper and then connect the research part with answers to questions. And connect all in the conclusion together with answering what are the future expectations.
Response 1: We appreciate the reviewer’s insightful and helpful comments on our manuscript. Review papers and other article types can have a more flexible structure than research articles according to the template of manuscripts submitted to Remote Sensing. The section titles suggested in the template are for articles not for reviews. Therefore we have decided to keep the structure of the paper. But we have deepened the discussion and connected the research part, discussion and future expectations in the conclusions.
Point 2: Please delete “Type of the Paper”: in line 1.
Response 2: Amended as suggested.
Point 3: Keywords should be in alphabetical order.
Response 3: Amended as suggested.
Point 4: Abstract could be more explicit in what the paper is about.
Response 4: Amended as suggested.
Point 5: Fig 2 source, please check all the Figures where there is no source information. Also, please check an information for Tables.
Response 5: All figures and tables were checked for source information and amended if necessary.
Reviewer 4 Report
GNSSs are powerful technology of location and navigation for both the mainland and at sea. One way to improve the accuracy of GNSSs is augmentation systems. This paper discussed and presented the issues and weaknesses of existing International Maritime Organization recommendations, guidelines, requirements, performance standards, and future concepts of GNSS performance standards of maritime position sensors. Moreover, integrity monitoring was addressed as the main issue, and recommendations based on solutions implemented in aviation and the latest research were proposed. Which is useful for GNSSs’ users.
There are some comments and suggestions about their work:
1. Speciality domain:
- Glonass should be written as GLONASS.
- Page 557: IMU (in the field of navigation) stands for inertial measurement unit. However, the fusion should be (inertial navigation system) INS/GNSS.
2. Writing domain:
- Sentences are too long, please break them up to make it easy for readers.
- Too many abbreviations in this paper, so it is necessary to have a way to manage them such as using a table.
- Contents of the paper is too long:
+ Some paragraphs are quite similar, or sentences are repeated: e.g. lines 465-467 and 508-510. Check and make them logical and concise.
+ Reduce parts related to mathematical theory, just keep parts of its applications.
- Conclusion section is too long. Don’t need to have too many explanations or discussions in this section.
- No Section 5 but Section 6.
- Carefully check UPPERCASE and lowercase letters.
Author Response
Point 1: Contents of the paper is too long: 1) Some paragraphs are quite similar, or sentences are repeated: e.g. lines 465-467 and 508-510. Check and make them logical and concise. 2) Reduce parts related to mathematical theory, just keep parts of its applications.
Response 1: We appreciate the reviewer’s insightful and helpful comments on our manuscript. The contents of the paper have been amended as suggested, parts of mathematical theory have been moved to the appendix A.
Point 2: Conclusion section is too long. Don’t need to have too many explanations or discussions in this section.
Response 2: The structure of the paper has been amended. The section “Discussion” has been added . The conclusions have been shortened to the most significant ones.
Point 3: Glonass should be written as GLONASS. Carefully check UPPERCASE and lowercase letters,
Response 3: Amended as suggested.
Point 4: Page 557: IMU (in the field of navigation) stands for inertial measurement unit. However, the fusion should be (inertial navigation system) INS/GNSS.
Response 4: Amended as suggested.
Point 5: Sentences are too long, please break them up to make it easy for readers.
Response 5: Amended as suggested.
Point 6: Too many abbreviations in this paper, so it is necessary to have a way to manage them such as using a table.
Response 6: Abbreviations are explained in order of their appearance according to MDPI instructions. To keep the paper concise we have decided to skip a table of abbreviations.
Point 7: No Section 5 but Section 6.
Response 7: The section Discussion has been added as 5, so Conclusions remained as 6.
Reviewer 5 Report
400 recorded positions are too less to be a good example.
Author Response
Point 1: 400 recorded positions are too less to be a good example.
Response 1: We appreciate the reviewer’s remark. The number of positions resulted from randomly selected 15min. observation (from 48h records) corresponding to the IMO continuity requirement (duration of operation phase) that passed consistency tests. The number was much lower than the nominal 900 positions recorded every 1s probably due to shadowing and multipath. We have selected another 15min. data samples which are of 900 recorded positions and replaced the relevant figures and tables.
Round 2
Reviewer 1 Report
The manuscript has been significantly improved in this modified version of the article. I thank the authors for their serious and positive work. I think it might be ready now for publication.
Thank you.
