A Novel Intrapulse Beamsteering SAR Imaging Mode Based on OFDM-Chirp Signals
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThis paper proposed a SAR imaging approach that combines the OFDM-Chirp signals and intrapulse beamsteering system, which improves the performance of fault tolerance to the interference signals. Experimental data is employed to validate the effectiveness of the method. The idea is interesting and original, making it worth publishing, while the paper still need sufficient improvement before it can be published.
- Some recent articles of related research field is suggest to be covered in the background of the manuscript:
[R1] X. Zhang, H. Wu, H. Sun, and W. Ying. Multireceiver SAS imagery based on monostatic conversion. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, vol. 14, pp. 10835-10853, 2021.
[R2] J. Zhu, Y. Song, N. Jiang, et al. Enhanced Doppler Resolution and Sidelobe Suppression Performance for Golay Complementary Waveforms. Remote Sensing, 15(9), 2023, 2452(1-10).
[R3] W. Liu, J. Liu, T. Liu, H. Chen, and Y. Wang, Detector design and performance analysis for target detection in subspace interference. IEEE Signal Processing Letters, 2023, 30: 618-622.
- The grammar should be double checked and improved. Besides, there are also some typos in the paper.
- The results are not clearly expressed, say, in Fig. 8, whether other targets has the same ambiguity performance; for Fig. 11, it is still not convictive after reading the illustration of the figure, and it is suggested to make some quantitative analysis about the extent that the OFDM-Chirp outperforms the LFM.
- In the conclusion, the quantitative indexes that indicate the superiority of the proposed work should be included.
The grammar needs double check, and there are also some typos in the paper.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe authors describe an intrapulse beamsteering radar using OFDM-chirp waveform. Due to its novelty, I think this manuscript is worth publishing in Remote Sensing: Special Issue. However, several points need clarifying and certain statements require further justification.
1. The authors have published several papers related to this topic, MIMO radar. This manuscript should be a development along this line. Specifically, following manuscript (S. Wang et al., “The intrapulse beam steering radar based on OFDM Chirp” J. Phys. 1607 (2020)012061) deals with similar content. There are several overlapping parts such as figures, equations, and sentences. If this manuscript is treated as a published one, the authors should refer this manuscript. Even if this is not treated as a published one, the authors should be careful about expression.
2. The difference from the previous paper should be made clear. It seems that the main difference point is obtaining the simulation imaging. However, I think there is no clear difference between the images obtained with LFM signal and OFDM-Chirp signal. The authors should discuss the difference point clearer.
3. It is difficult to see a comparison compared to the previous paper. Need to show quantitative improvement.
4. Line 348-349: Some disadvantages should be discussed in the “Discussion section”.
5. Typos:
1) References: The reference ([6] and [16]) and ([8] and [14]) are the same. Please correct.
2) Line 338: I think “Figure 9” will be “Figure 10”.
3) Line 341: I think “Figure 10” will be “Figure 11”.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsDear authors,
The method you are proposing does brings some novelty to the field of satellite SAR imaging.
You have thoroughly described the method with a focus of the advantages of the method.
Here, would like to ask you to provide discussion regarding effects OFDM may have to the sidelobes during radar processing. To the best of my knowledge that is the most limiting factor in the real systems.
Regarding your simulations:
1. Undulations of the ground are rarely random. However, take this just as remark for your future studies, since I do not ask you change this assumption in this paper.
2. On the other hand, the data you provided in the simulations are lacking. Two parameters are not discussed at all:
a. Flight speed of the satellite
b. Aperture angle needed to produce the images.
Please, update the simulation section with the missing data and the discussion regarding them.
Best regards,
Reviewer
Comments on the Quality of English LanguageEnglish language used in this paper is fine from the grammar stand point.
However, I advise to reduce number of unnecessary long sentences in order to improve readability of the paper.
Author Response
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Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsThis paper proposes a novel radar mode with the combination of intrapulse beamsteering in elevation and OFDM-Chirp signals. This mode can improve the performance and fault tolerance to interference signals. The simulation for both point targets and distributed targets are carried out to verify the feasibility of the proposed mode. There are some small problems that need improvement before publication.
1, "SO" in abstract should be "So";
2, "Point Targets simulation result" is repeated in Figure.8.
3, The ISLR, PSLR and resolution should be given in this paper.
Comments on the Quality of English LanguageMinor editing of English language required.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe issues in the first round have been responsed.
Reviewer 2 Report
Comments and Suggestions for AuthorsI have read the author’s answer and revised manuscript, and feel that the authors have managed to address the referee’s comments.
