Worldwide Availability of Maritime Medium-Frequency Radio Infrastructure for R-Mode-Supported Navigation

Round 1

Reviewer 1 Report

Please, decide whether to use B.or A. English. (e.g.line 187)

Improve definite and indefinite articles through the text.

Do use Passive forms instead of active! Do not use WE!

Rewrite the sentence in line 116 in terms of grammar.

In Figure 3, line 138, the sentence is not finished or?

In Figure 13 is not passenger but passenger ships; the same is for cargo....

Considering methodology, it is possible to figure out that it relies on previous research on this topic. 

Author Response

“Please, decide whether to use B.or A. English. (e.g.line 187)”

Response:
Thank you for the hint on the language style. We had our text checked by an English speaking professional to an A.E. standard before paper submission and got the manuscript revised back. We could not find any further improvements after receiving your remark and would like to know more specific examples for incorrect/mixup of A.E. and B.E. styles.

            “Improve definite and indefinite articles through the text.”

            Response:

See paragraph above. We went through the text but could not follow this argument all along. In case of doubt we ask for more specific examples.

            “Do use Passive forms instead of active! Do not use WE!”

            Response:

Thank you for the input. We followed your advice and replaced we and our with passive forms or “the authors” forms.

“Rewrite the sentence in line 116 in terms of grammar.”

            Response:

We revisited the formulation and slightly revised the order to make the sentence more easily readable.

“In Figure 3, line 138, the sentence is not finished or?”

            Response:

During copying of the text one letter at the end of the caption went missing. We fixed “are” to “area” which fixes the caption and clears up the confusion.

“In Figure 13 is not passenger but passenger ships; the same is for cargo....?”

            Response:

Thank you for the information. Since not writing “-ships” at the end of the legend made the naming of ships inconsistent, we followed your advice and changed the legend labels accordingly.

“Considering methodology, it is possible to figure out that it relies on previous research on this topic.”

            Response:

Following your advice we included some more references in the introduction that show that the paper is based on current research activities in the field of R-Mode.

Reviewer 2 Report

This paper focuses on the R-Mode maritime navigation and researches on the availability of radio beacons to support it. However, I would like to see a few things explained. Specifically:

• explain in detail what R-Mode is.
• explain in more detail the AIS and VDES.

Since there is satisfying coverage coming from T-AIS, duplicate messages may be received from two or more receivers. This indicates that any erroneous messages might be corrected considering the majority of the received messages. I would like to see the following things:

• Please explain in detail what are the benefits of upgrading worldwide beacons to support R-Mode.
• Refer explicitly to the problems that will be tackled by R-Mode.
• Make a sufficient comparison between AIS and R-Mode in a paragraph.

Author Response

“This paper focuses on the R-Mode maritime navigation and researches on the availability of radio beacons to support it. However, I would like to see a few things explained. Specifically:              explain in detail what R-Mode is.”

            Response:

We extended the introduction to explain more in detail how R-Mode (MF, VHF) works. The authors think that more details are not necessary to understand the research topic of this paper. More details can be found in the references which were cited especially in the introduction.

“explain in more detail the AIS and VDES.”

            Response:

Some more details are given in the introduction. Due to the fact that VDES is only mentioned briefly as a future system that supports R-Mode further explanations are not necessary. References for VDES are given in the new version of the paper.

“Since there is satisfying coverage coming from T-AIS, duplicate messages may be received from two or more receivers. This indicates that any erroneous messages might be corrected considering the majority of the received messages. I would like to see the following things:

Response:

The used AIS data set was already processed by the AIS data provider to remove erroneous received messages. This can be done by considering the checksum of each AIS message. We got an error free data set. Gaps in the data set that might be caused by erroneous received messages were handled as described in the paper.

    Please explain in detail what are the benefits of upgrading worldwide beacons to support R-Mode.”

“Refer explicitly to the problems that will be tackled by R-Mode.”

            Response:

We added a section in the introduction which highlights the benefit to have an R-Mode system available and which shows the differences between GNSS and R-Mode. Furthermore, we highlighted that R-Mode is not affect by same sources of signals disturbances as GNSS.

“Make a sufficient comparison between AIS and R-Mode in a paragraph.”

            Response:

We do not understand this request. AIS is a communication system and R-Mode a navigation system. Please explain.