Ground-to-Drone Optical Pulse Position Modulation Demonstration as a Testbed for Lunar Communications
, Benjamin P. Dix-Matthews 1,2, Shane M. Walsh 1,2, Ayden S. McCann 1,2, David R. Gozzard 1,2, Alex M. Frost 1,2, Charles T. Gravestock 1,2 and Sascha W. Schediwy 1,2
Round 1
Reviewer 1 Report
The contribution of this paper lies in demonstrating the operation and test of a hardware simulator for high photon efficiency ground-to-drone free-space optical (FSO) communications, where a drone was used as a proxy. In this regard, results with respect to bit-error rate versus voltage of received slots for transmitted and received data were provided. The paper is in general well written and easy to follow and the experimental results are interesting. However, the authors did not adequately discuss previous work on similar experimental methods and it is difficult to ascertain the technical novelty of the manuscript. More importantly, the contents and the principles of the manuscript are well-suited to a conference paper rather than a journal paper. In particular, there is no mathematical background to compare theoretical and experimental results, more details and figures about the results are needed, and the technical contribution is limited. Hence, this paper cannot be accepted in its current form.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
1, although drone-to-ground communication can be sometimes act as proxy for space-to-ground communication. there are also many different between these two scenarios such as transmission distance, full angle of optical antenna, optical power of transmitter and receiver sensitivity etc. If a drone-to-ground communication system is used as a proxy of space-to-ground communication, all the important factors of the payloads should be designed to be comparable with the space-to-ground systems. However, this paper just show a ordinary drones-to-ground communication system, there are no comparation between this system and any other space-to-ground system or lunar communcation systems.
2, atmospheric turbulence is an important factor that deteriorate the performance of space-to-ground laser communication systems, which is not included in this paper.
3, the receiver sensitivity is about -30dBm, however, the sensitivity of space-to-ground system and lunar system is at least -40dBm and -60dBm. so the transceiver can not act as a proxy too.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
This manuscript proposes retroreflected laser links to drones as a useful step towards further ground-to-sky and ground-to-space FSO communications demonstrations. Generally, the manuscript is well-written and the testing results seem solid. However, there are some issues to be addressed:
1. A more detailed review on similar works, especially on experimental works, on FSO communications using drones is expected in the Introduction part.
1. What are the turbulent conditions in the tests, e.g., the refractive structure constant or the wind speed? How to quantify the turbulent influence in your tests.
2. The authors use drones as proxies for FSO communication satellites. Please explain how to simulate the high-speed movement characteristics of the satellite using the drones.
3. Please clarify whether the demonstrated experiment was performed during the day or at night.
4. Only BER is presented in the work. What about other metrics, e.g., the signal-to-noise?
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 4 Report
No comment.
Author Response
No comments or suggestions were raised by Reviewer 4.
Round 2
Reviewer 1 Report
The authors have addressed my major concerns in a reasonable manner. The manuscript has been improved and can be accepted for publication as a technical note.
Reviewer 3 Report
The authors have addressed all my concerns. I have no further comments.
