Random Stepped Frequency ISAR 2D Joint Imaging and Autofocusing by Using 2D-AFCIFSBL
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe paper presents a 2-D method based on sparse Bayesian learning to accomplish joint ISAR imaging and autofocusing for random stepped frequency ISAR. The authors propose to use 2D-CIFSBL algorithm for ISAR imaging which relaxes the evidence lower bound to avoid matrix inversion. This approach has lower computational complexity than the traditional SBL. Experimental results on both simulated and measured datasets show that the proposed method can achieve well-focused images, even with low SNRs, efficiently. The paper was well-written. The background literature was presented relevantly and sufficiently. The proposed method was described in details so that readers with enough knowledge of the field can reproduce it. The reviewer only have a few minor comments on this paper. Please see the highlights in the attached file.
Comments for author File: 
Comments.pdf
The paper was well-written. But it would be nice to scan through it again in the revised manuscript.
Author Response
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Author Response File: Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThis paper proposes a novel 2D joint imaging and autofocus method for random step frequency inverse synthetic aperture radar (RSFISAR) systems. The method is not innovative and the imaging quality has not been significantly improved compared with the existing. The detailed comments are provided as follows:
(1) The abstract mentions the notable Electronic Counter-Countermeasure (ECCM) characteristics of RSF, but the detailed explanations of its specific advantages and practical applications is not given. In the introduction or methods section, please illustrate the specific advantages of RSF compared to traditional methods and discuss its effectiveness in practical scenarios.
(2) The background and related work sections may not comprehensively cover the existing literature.
Please add more discussion on the related works, particularly the significance in 2D joint imaging and autofocusing. Highlight how the proposed method differs from and improves upon existing approaches.
(3) The methods section lacks the detailed descriptions of key technical aspects, particularly the challenges encountered and solutions implemented. Please provide more detailed descriptions of the algorithm's implementation, including potential challenges and their solutions. Adding pseudocode or flowcharts could also enhance understanding.
(4) In evaluating the computational complexity, the author only compares the computational time of different algorithms.Please derive the computational amount of different algorithms, for example, the scale of complex multiplication required. It is suggested to compare the computational amount of the proposed method with other methods, and analyze and compare the time complexity and space complexity.
(5) According to the manuscript, the proposed method only applies the 2D focusing SBL framework to ISAR imaging. It is suggested that the author elaborate the increment of the proposed method compared with the existing algorithm.
(6) In the comparison part of experimental results, the imaging results (Fig. 5, Fig. 7, Fig.9, Fig 11, Fig 15, Fig 16) show that the proposed algorithm and other algorithms have not improved significantly, indicating that the author's improvement is not obvious.
Comments on the Quality of English LanguageN/A
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe paper introduces an interesting joint imaging and autofocusing method for RSF ISAR based on 2D-CIFSBL. However, the organization of the paper could be improved for better clarity and flow. The introduction could provide more background on RSF ISAR imaging and motivate the need for joint imaging and autofocusing. Additionally, the imaging model could be presented earlier before discussing the proposed method.
1. In the introduction, the significance of RSF ISAR compared to other methods could be further emphasized. For example, its advantages in anti-interference and hardware requirements could be highlighted.
2. The imaging model could be presented before discussing the proposed method to establish the problem formulation. This would provide a clear transition into the motivation for the proposed 2D-AFCIFSBL method.
3. In the proposed method section, the equations for the matrix form of the updates could be more clearly explained or derived. This would help readers better understand the transition from vector to matrix operations.
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsThe quality of the manuscript has been improved. I still have two comments as follows:
(1) The estimation of phase error has been estimated in section 3.2. Please first analyze which the estimated accuracy of the phase error matrix affects the proposed method, and then add the experimental result about the convergence curve of the estimated error of the phase error matrix in the experimental results.
(2) Due to the relaxation of the SBL based problem, the algorithm is biased towards the strong scattering points in the reconstructed image, which can be seen in Fig.5.7.9.11.15.16. Although the IC and IE indexes can be improved in the results, the weak scattering points are considered as noise. Thus, the structure information of weak scattering region is not reflected in the real data experiments.
Comments on the Quality of English Language
No other comments.
Author Response
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Author Response File: Author Response.pdf
