Generalization of the Synthetic Aperture Radar Azimuth Multi-Aperture Processing Scheme—MAPS

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The paper presents an interesting extension of MAPS to bistatic SAR configurations and non-conventional channel arrangements. The theoretical framework appears sound, and the use of simulations to validate the proposed methods is commendable. The authors have addressed an important gap in the current literature by considering scenarios beyond the traditional single-platform, zero-Doppler assumptions.

However, the paper would benefit from moderate editing to improve clarity and readability. Some sentences are overly complex and could be simplified for better understanding.

Comments on the Quality of English Language

 

 

Author Response

Dear Reviewer,

our answer is in red in the attached file

Regards,

PG

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript proposes an extension of the high-resoluton wideswath concept MAPS to cases different from the canonical MAPS, ie not a single antenna monostatic SAR single antenna composed of (usually equispaced) antenna elements. 

 

The abstract is concise, and clearly defines the scope of the manuscript, the challenges, and the main findings. The manuscript is in general well structured and readable, given the complexity of the topic.

I recommend this manuscript for publication subject to minor revision.

My only comments are related to the simplifications made in the system setup, particularly the assumption of identical straight trajectories over a flat earth for the involved platforms. I would like to see a short discussion of what effects this simplification ignores. Specifically:

* The authors apply an approximation of the hodograph (eq 12) as a second order polynomial approximation (eq 17). I would recommend including at least a remark about the limitations of this approximation, in particular in a high-resolution context. Typically, a higher order (semi-) numerical approach is needed for geometries of high bistatic angle, e.g (Neo, 2007) or (D'Aria, 2007).

* I would also include a remark about the spatial invariance property of the derived results (21)-(23), realizing that the assumption of straight linear platform trajectory and a flat earth makes this less of an issue. It would still be a good idea to indicate that additional details will have to be worked out in a more involved in a real-world curved orbit / curved earth scenario. 

(Neo, 2007) Y. L. Neo, F. Wong and I. G. Cumming, "A Two-Dimensional Spectrum for Bistatic SAR Processing Using Series Reversion," in IEEE Geoscience and Remote Sensing Letters, vol. 4, no. 1, pp. 93-96, Jan. 2007, doi: 10.1109/LGRS.2006.885862.

(D'Aria, 2007) D. D'Aria and A. Monti Guarnieri, "High-Resolution Spaceborne SAR Focusing by SVD-Stolt," in IEEE Geoscience and Remote Sensing Letters, vol. 4, no. 4, pp. 639-643, Oct. 2007, doi: 10.1109/LGRS.2007.903081.

Comments on the Quality of English Language

the manuscript uses both "odograph" and "hodograph" for the "target-to-sensor range history function" R(t).  I believe the latter is the correct one in this context (?)

Author Response

Dear Reviewer,

our answer is in red in the attached file

Regards,

PG

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

 

The paper analyzes the advantages and the drawbacks of using the SAR azimuth multichannel technique known as Multi Aperture Processing Scheme (MAPS), and the paper is interesting.

However, some issues exist need to be addressed:

1、The structure is quite chaotic, for example, both the fourth and sixth sections are Simulation Results.

2、The paper is too long and does not clearly express the main innovations. Need to reorganize the structure and innovative points of the paper.

3、Only one-dimensional signal simulation was conducted, lacking two-dimensional SAR signal simulation and imaging processing.

Author Response

Dear Reviewer,

our answer is in red in the attached file

Regards,

PG

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

The authors present a general approach for the MAPS reconstruction that goes beyond the formulation valid for a single-platform and zero-Doppler (SP-ZD) instrument. Here are some comments/questions.

1) The section arrangement of this paper is confusing. There are two simulation sections, namely Sec. 4 and Sec. 6.

2) The simulation in this paper is simple and ideal. It is suggested to consider more practical factors and present simulation results for different types of target.

3) In the last paragraph of Section 1, Sec. 6 does not appear.

Comments on the Quality of English Language

There are some English language issues in the manuscript. For example, the sentence “a more physical approach, based on discrimination of the Direction of Arrivals (DoAs) is pursue.” and the sentence “In Multiple Aperture Processing Scheme (MAPS) SAR, the same antenna It is used as a whole for transmission (thus maximizing the peak transmitted power) but is partitioned along azimuth by grouping tiles to create multiple receiver channels.”

Author Response

Dear Reviewer,

our answer is in red in the attached file

Regards,

PG

Author Response File: Author Response.pdf

Round 2

Reviewer 4 Report

Comments and Suggestions for Authors

I have no questions.