A Novel Azimuth Channel Errors Estimation Algorithm Based on Characteristic Clusters Statistical Treatment
and Junhua Yang 1
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsPlease see the comments in the attachment.
Comments for author File: 
Comments.pdf
Author Response
The questions answered are shown in the attached file.
Author Response File: Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsComments on manuscript remotesensing-3441856
The “error” discussed in this study is confusing. Could the authors clearly define “error” in this research? In the science of measurement, the error indicates the difference between a measured value of a quantity and its unknown true value. Therefore, the error can only be obtained statistically. To surrogate this dilemma, some investigators use the difference between the measured value and a reference or standard value to determine the error. Note that, the difference or variance of measurements is not the “error”; it is more like the “uncertainty”. Statistically, we use the coefficient of determination (goodness-of-fit), deviation, standard error, estimation errors (the inherent and processing errors), etc. to describe the accuracy of measuring. I suggest the authors provide a more specific and convincible definition plus the physical meaning of the “channel errors” in the Introduction section. This will be a ground-breaking contribution to this subject because most previous researchers ignore this crucial point.
Table 11 is mentioned on page 20, but Tables are missing after Table 8.
The abstract is a stand-alone section, and abbreviations/acronyms are unnecessary, particularly for those that appear only once in the abstract (HRWS for example); therefore, they are redundant. It is fine for the authors to use abbreviations/acronyms in the abstract, but the explanations of the abbreviations/acronyms must be given again in the main text. Hence, introducing the abbreviations/acronyms only in the main text should be a good practice.
Most of the techniques, algorithms, models, and equations are adopted/modified from other publications, however, the citations are vague or missing. This is against basic academic ethics.
Several figures need the scale, legend, and axis title.
The reference list needs an overhaul because the format doesn’t exactly conform to the MDPI style and weird symbols appear. Read the journal’s instructions for more details
Comments on the Quality of English Language1. Avoid using identical wording/phrase too close. 2. Be aware of using correct punctuation marks in a long sentence.
Author Response
The questions answered are shown in the attached file.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsAn algorithm capable of estimating errors between azimuth channels in a high-resolution, wide-area multi-channel SAR system (HRWS) is presented. Methodologically, the approach is based on the analysis of phase differences between received signals. Particular attention was paid to the correction of calibration errors.
The findings demonstrate that the suggested technique greatly raises phase error estimate accuracy. As a result, the SAR system performs better overall. Understanding is made easier by the manuscript's coherence and logical flow.
The subject matter is relevant to the field of remote sensing and consistent with the aims of the journal.
The proposed algorithm represents an innovative solution, improves the calibration and performance of the SAR system, however it should be described in more detail.
The paremeters used to generate the synthetic data should be more detailed.
It is suggested that a table be implemented that highlights the performance of the proposed algorithm compared to other existing approaches, with metrics such as RMSE or percentage errors.
The limitations of the proposed algorithm, its weaknesses and critical points should be examined more clearly and practically.
It is suggested that opportunities for improvement of the algorithm be further detailed.
The paper is grammatically correct, easily readable, well-structured, and intelligible.
The manuscript is certainly significant in the field of remote sensing, in my experience, with the above mentioned adjustments, which would improve the clarity and completeness of the paper, it could be considered for publication.
Author Response
The questions answered are shown in the attached file
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsIn this paper, a novel method of channel system error calibration based on image domain processing for high resolution wide-width SAR system is proposed. Overall the theory and verification are well illustrated, the system composition and imaging results are introduced in detail. However, there are still some points that are not very clear, here are some suggestions.
1. When calculating the phase errors between channels, this article obtains the errors between channels by selecting the phase errors of characteristic points in different characteristic clusters. It can be seen that formula 20 in this paper first obtains the phase errors between different channels and then takes the weighted average. Can we first obtain the phase of all the special points between different channels, and then calculate the phase error between channels in a unified manner?
2. Considering the weighting coefficient in this paper, we can see that the top 4 largest values occupy a larger proportion, 0.99. And then it decreases in turn. If there are 1 phase error in the 4 maximum value is obviously not consistent with 3σ, is there flexible adjustment in the actual applying of the actual imaging?
Author Response
The questions answered are shown in the attached file.
Author Response File: Author Response.pdf
Reviewer 5 Report
Comments and Suggestions for AuthorsThis article contains a few questions：
1. Will selecting different clusters and feature points lead to changes in error estimation?
2. Whether the change of signal amplitude after the orientation Fourier transform affects the processing of subsequent data?
3. How to determine the ratio of different weight coefficients in Table 1?
4. After error correction, how to solve the Doppler fuzzy problem, which is not clearly reflected in the imaging algorithm process?
5. The description of experimental results in Figure 3 is not detailed. Does Figure 3 generate three-point target imaging or point target imaging with Doppler blur, in addition, the experimental results are not clear?
6. Only phase error was added in the simulation experiment, and distance error and amplitude error were not mentioned.
7. Where is Table 11 referred to in this paper?
8. Why is Amp order for the 12th feature point in Table 8 XXX?
Author Response
The questions answered are shown in the attached file.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsComments on manuscript remotesensing-3441856-v2
Thank the authors for their endeavors in revising the manuscript which has improved greatly except for a few minor writing issues. I suggest the authors groom the manuscript meticulously, particularly in using abbreviations and symbols. All abbreviations must be explained in the main text, even if they are commonly adopted in the authors’ specific field. The reason is that in other communities, the abbreviations are slightly different even the originals are exactly the same. Some units should be kept in their original forms, for instance, never replace “μs” with “us”.
Since the problems are trivial, a turn-around review is unnecessary.
Comments on the Quality of English Language
See "Comments and Suggestions for Authors".
Author Response
Thank you very much for taking the time to review the second version manuscript. Please find the detailed responses in the attached file.
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsThe comments have all been addressed.
Author Response
Thank you very much for taking the time to review the second version manuscript.
