Review Reports

Round 1

Reviewer 1 Report

Thank you for that interesting contribution.

The paper is very well written, theory is clearly described and well supported by a compact set of relevant simulations.

For the final version please consider the following:

1. Did Figure 2 include an estimate of the number of signal sources (including multipath sources)?

2. How do you define "diffuse" exactly? Diffuse as opposed to specular to my knowledge is characterized by a smooth angular "smearing" across multiple angles close to target angle, rather than additional angles that are not a perfect mirror (so target surface scattering back in random directions). In your simulations, however, you defined 4 DOAs that are located at quite distinct angles - or do you use random delays as well to simulate diffuse behavior?

3. Regarding Monte Carlo trials it would be great to have an additional figure showing how RMSE converges for particular multipath scenarios. I suppose there are several combinations of true target angle and multipath components that will lead to particularly good or bad performance for each algorithm, so it would be interesting to see if there is a correlation / dependency.

 

Author Response

 

Dear reviewer:

        Thanks very much for taking your time to review our manuscript. We have carefully read through the comments and made proper revisions. We greatly appreciate your time and efforts to improve our manuscript for publication. Please see the attachment.

            

Author Response File: Author Response.pdf

Reviewer 2 Report

The paper is generally well written, and it presents an approach of some interest. No specific comments shall be made, and the paper can be considered as ready for publication.

Author Response

Dear reviewer:

         Thanks very much for taking your time to review our manuscript. We have carefully read through the comments and made proper revisions. We greatly appreciate your time and efforts to improve our manuscript for publication.

          We checked the language and writing carefully again, thank you!

Reviewer 3 Report

The letter, in general looks solid, however I found two shortcomings:

• additive noises in (1) and (2) should be called like in (6)
• there is no reference to primary or at least review TR works like e.g.:

Fink, “Time reversal of ultrasonic yields – Part I: Basic principles,” IEEE Trans. Ultrason. Ferroelectr. Freq. Control, vol. 39, no. 5, pp. 555–567, Sept. 1992.

Wu, J.-L. Thomas, and M. Fink, “Time reversal of ultrasonic yields—Part II: Experimental results,” IEEE Trans. Ultrason. F erroelectr. Freq. Control, vol. 39, no. 5, pp. 567–578, Sept. 1992.

F. M. Moura and Y. Jin, “Detection by time reversal: Single antenna,” IEEE Trans. Sig nal Processing, vol. 55, no. 1, pp. 187–201, Jan. 2007.

B. E. Anderson, C. Larmat, T. J. Ulrich, “Time-reversal”, Acoustics Today, January 2008.

E. Yavuz and F. L. Teixeira, “Ultrawideband microwave sensing and imaging using time-reversal techniques: A review,” Remote Sens., vol. 9, pp. 466–495, Sept. 2009.

de Rosny, G. Lerosey, and M. Fink, “Theory of electromagnetic time-re-versal mirrors,” IEEE Trans. Antennas Propagat., vol. 58, no. 10, pp. 3139–3149, Oct. 2010.

 

Author Response

Dear reviewer:

Thanks very much for taking your time to review our manuscript. We have carefully read through the comments and made proper revisions. We greatly appreciate your time and efforts to improve our manuscript for publication. Please see the attachment.

Author Response File: Author Response.pdf