Shipborne Acquisition, Tracking, and Pointing Experimental Verifications towards Satellite-to-Sea Laser Communication

Round 1

Reviewer 1 Report

 

The Paper deals with Acquisition, tracking, and pointing of ATP technology in free space laser. In this paper, the authors report the tracking of Low-Earth-orbit satellites using ship-borne ATP and verify the feasibility of establishing optical links between laser communication satellites and ships in the future. In particular. The authors designed an acquisition strategy for satellite-to-sea laser communication. In addition, a method was proposed for improving ship-borne ATP pointing error. they tracked some stars at sea, achieving a pointing accuracy of less than 180 μrad. By acquiring and tracking of some Low-Earth-orbit satellites at sea, it was a tracking accuracy of about 20 μrad achieved. The results achieved in this work experimentally demonstrate the feasibility of ATP in satellite-to-sea laser communications.

 

General comments:

 

the theoretical considerations on the topic are very detailed and easy to understand, but for readers who are familiar with the topic they are somewhat excessive. Under certain circumstances it could be tightened up.

 

Figure 6 Add device type to caption

The purpose of Figure 7 is not apparent to the reader.

Fig. 8-11 The font is difficult to read in relation to the text.

The result presentation is clear and easy to understand. In view of the detailed theoretical considerations, the following discussion could more emphasize the results and the practical benefits.

Author Response

.Response to Reviewer 1 Comments

Point 1: Figure 6 Add device type to caption.

 

Response 1: According to the opinions, it is modified as follows: "Figure 6. The ship-borne ATP system. The ship-borne ATP system showing the uplink beacon, coarse camera, and the attitude pre-compensation unit."

 

Point 2: The purpose of Figure 7 is not apparent to the reader.

 

Response 2: I deleted Figure 7.

 

Point 3: Fig. 8-11 The font is difficult to read in relation to the text.

 

Response 3: I've redrawn it

 

 

Point 4:The result presentation is clear and easy to understand. In view of the detailed theoretical considerations, the following discussion could more emphasize the results and the practical benefits.

 

Response 4: In conclusion, the results of this paper are summarized first:"

We tracked some stars at sea, achieving a pointing accuracy of less than 180 μrad. We then acquired and tracked some Low-Earth-orbit satellites at sea, achieving a tracking accuracy of about 20 μrad. "

Reviewer 2 Report

Thank you for your contribution. 

 

I think your paper would be more interesting and understandable to the reader if you made it very clear which errors you are referring to in the different paragraphs. For example, you mention a 60 ms lag error but don't discuss why this exists.  Also, you include encoder and bearing "stiction" errors in table 2 but these are not measurement errors like the others and have entirely different characteristics.  

 

Most (or many) mobile satcom systems use gyro (angular velocity) stabilized gimbals to take out most of the motion and then use an INS/GPS in as a reference for an outer position loop. However, it appears that you do not use an inner gyro loop.  It would be very helpful to include a control system block diagram with some description so it is apparent what you are talking about.

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

The manuscript „Ship-borne acquisition, tracking, and pointing experimental verifications towards satellite-to-sea laser communication” by Dong He et al. deals with satellite-to-sea laser communication. Several aspects of improving the pointing error are discussed in the manuscript and connected to experiments tracking stars and Low-Earth-orbit satellites. This topic is interesting for publication in Applied Sciences.
However, some parts of the manuscript need to be improved before recommending the paper for publication.
1. Shipborne instead of Ship-borne.
2. Table 2: All other values in the manuscript are given in mrad.
3. Several spelling errors and missing space characters connected with the reference to figures. E.g. l.227: Figure 2, l.251: Figure 5(b), l.256: (Figure 6) mainly etc.
4. References to Figures 8 to 10: l.271: Figure 8 and Figure 9, l.275: Figure 10
5. l.289: was 160 µrad
6. line 300: verb missing: A position error of …
7. References: Please check that the references meet the journal style guide and are consistently formatted.
8. Figure 7 is not necessary. The information is fully described in the text.

Author Response

.Response to Reviewer 3 Comments

 

 

 

Point 1: Shipborne instead of Ship-borne.

 

Response 1: I have changed it as suggested.

 

Point 2: Table 2: All other values in the manuscript are given in mrad.

 

Response 2: I have changed the units in table 1 to mrad.

 

 

Point 3: Several spelling errors and missing space characters connected with the reference to figures. E.g. l.227: Figure 2, l.251: Figure 5(b), l.256: (Figure 6) mainly etc.

 

Response 1: I have changed it as suggested.

 

 

Point 4: References to Figures 8 to 10: l.271: Figure 8 and Figure 9, l.275: Figure 10

 

Response 2: I have changed it as suggested.

 

 

 

Point 5: l.289: was 160 µrad

 

Response 1: I have changed it as suggested.

 

Point 6: line 300: verb missing: A position error of ….

 

Response 2: According to the opinions, it is modified as follows: " A position error is less than 0.1mrad at 2000 km."

 

 

Point7: References: Please check that the references meet the journal style guide and are consistently formatted.

 

Response 1: I have changed it as suggested.

 

Point 8: Figure 7 is not necessary. The information is fully described in the text..

 

Response 2: I deleted Figure 7.