Precise Ambiguity Performance Evaluation for Spaceborne SAR with Diverse Waveforms

Round 1

Reviewer 1 Report

In this paper, the authors focus on the ambiguity performance evaluation problem in spaceborne SAR data. Particularly, the modified azimuth ambiguity-to-signal ratio (AASR) and range ambiguity-to-signal ratio (RASR) formulas are given for the single polarization SARs and quadrature-polarimetric (quad-pol) SARs, which contributes a lot, for the system designer, to precisely evaluating the ambiguity performance. Overall, the idea is interesting, the paper is well-written and the results are promising. I have the following comments:

 

1.     Please introduce more about the state-of-the-art work on ambiguity supression such as [1-3].

2.     In my view, the motivation to integrate RASR and AASR with Waveform Diversity is not clear. Why do you need to do this? Please clarify this aspect more clearly.

3.     Motion error is a key problem in the practical application of SAR imaging[4], especially for LEO SAR. If there are motion errors, the motion errors will cause blurring in the SAR imagery. Can you give an explanation of is it possible for the proposed approach to get good performance with motion errors? Adding some experiments is intractable, but the authors could discuss this aspect.

4.     A language revision is necessary to fit some minor grammatical errors, e.g. the misuse of prepositions affects the readability of the paper.

5.     The authors should pay attention to the format of references.

 

[1 Y. Long, F. Zhao, M. Zheng, G. Jin, H. Zhang and R. Wang, "A Novel Azimuth Ambiguity Suppression Method for Spaceborne Dual-Channel SAR-GMTI," in IEEE Geoscience and Remote Sensing Letters, vol. 18, no. 1, pp. 87-91, Jan. 2021

[2] J. Ryu, D. -W. Yi, S. -Y. Kim and G. Yoon, "Suppression of Range Ambiguity in Spaceborne SAR With Elevation Beam Pattern Mask Design," in IEEE Geoscience and Remote Sensing Letters, vol. 19, pp. 1-5, 2022

[3] J. Chen, K. Wang, W. Yang and W. Liu, "Accurate Reconstruction and Suppression for Azimuth Ambiguities in Spaceborne Stripmap SAR Images," in IEEE Geoscience and Remote Sensing Letters, vol. 14, no. 1, pp. 102-106, Jan. 2017

[4] W. Pu and Y. Bao, "RPCA-AENet: Clutter Suppression and Simultaneous Stationary Scene and Moving Targets Imaging in the Presence of Motion Errors," in IEEE Transactions on Neural Networks and Learning Systems, 2022

 

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Please see the attached pdf file.

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

This manuscript presented the modified formulas of azimuth and range ambiguity-to-signal ratios for single polarization SARs and quadrature-polarimetric (quad-pol) SARs, which could be applied for accurately evaluate ambiguity-to-signal ratios performance. The topic is relevant and interesting. However, the manuscript could not be published until the following questions are clearly clarified.

1. Abbreviations should be well-known. Abbreviations like WD for Waveform Diversity and CCE for Cross-Corrlation Energy should be avoided.

2. There exists a Ba for processed Doppler bandwidth in equation (3). Please give this variable a detailed discussion when waveform diversity is applied.

3. Please check the image copyright on academic papers of the satellite image in all the figures.

4. The targeting imaging area in Figure 1 should be in a curve line to meet the actual situation.

5. Equation 12 should be presented with a note on when you can give the approximation.

6. It would be clearer if you could describe the waveform diversity in Figures 2,3 and 4.

7. When dealing with AASR, will the antenna beam pattern for different polarization remain the same? Or it could be different for each polarization mode?

8. In the simulations, point-like target simulation is not suitable for OFDM or up-down chirp signal because there exists no scenario which contains only one target, though the imaging result will be good. For OFDM and up-down signal, the "mess up things" will accrue when distributed targets exist, like in the real world.

9. The writing of this paper should be improved for better academic writing.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Please see the attached pdf file.

Comments for author File: Comments.pdf