Analysis of High-Frequency Communication Channel Characteristics in a Typical Deep-Sea Incomplete Sound Channel

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The article deals with analysis of high-frequency communication channel characteristics
in a typical deep-sea incomplete sound channel-
The article is interesting, original and deals with a topic related to the focus of the magazine.
The authors have worked out the problem well, the article is clear and conceptually well designed.
Individual chapters are logically arranged and supplemented with pictures and graphically presented data.

I propose to accept the article for publication.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

# Abstract
* invesgated -> investigated
* a lack of many 'commas', 'the', and so on

# 1.Introduction
* "... are generally regarded as among ..." - regarded as what?
* almost any sentence needs grammar and language corrections !!!
* pg.2 - what is the 'CIR' - all abbreviation should be explained

# 2.Experimental Overview -
* The title of the section should be changed. Probably you mean 'Overview of the experiments'
* 'experimatal area' - IMO - it is rater 'area of experiment(s)'
* Linear frequency modulation (LMF) - Is this a communication signal? I understand that it is a test signal designed only for evaluating a sound speed. This issue needs some explanations.

# 3.Underwater ...
* once again - what is the 'CIR'?
* the block 'Descending to complex baseband' has to be explained. Either you should write a few sentences or mathematical formulas.
* eq(2) - one should not use the same symbol - I mean 'T_c' - for two different means!!! First 'T_c' is used to represent a time sampling 'interval', and in eq(2) it represents the 'threshold of ...'

# 4.Experimental Analysis
* The title of the section suggests that you propose some kind of analysis that is experimental - it means somehow unique, or no one before has proposed such an analysis, or this analysis is completely different from a ' traditional analysis'. Is this really true?

Comments on the Quality of English Language

DEFINITELY - the paper has to be corrected by a native speaker. He/She has to be familiar with the topic deliberated.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Strong aspects:
The paper presents a study of underwater environment considering communication using high frequency sound. The authors analyzes the propagation delay and temporal coherence which are important parameters to characterize the channel quality.This research could be important for long range communication because water represents a good environment for sound transmission.

Weak aspects:

More details related to the real communication i.e. maximum data rate, BER and other parameters.

Author Response

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Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

If it is possible, include photos of the scenario.

Eliminate space after equations (2), (4), and (7).

Add sentences by explaining subsections 4 before subsection 4.1.

In Figure 10, add subfigures identified by (a), (b), (c), ...

Add future works with details.

Include abbreviations at the end of the paper,

Comments on the Quality of English Language

If it is possible, include photos of the scenario.

Eliminate space after equations (2), (4), and (7).

Add sentences by explaining subsections 4 before subsection 4.1.

In Figure 10, add subfigures identified by (a), (b), (c), ...

Add future works with details.

Include abbreviations at the end of the paper,

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

* pg 5. par 5
The sentence "Descending to complex baseband represents the conversion of the bandpass signal to an equivalent baseband signal." does not explain anything. The other blocks (from Figure 5) are rather clear, but the operation called by you "Descending to complex baseband" is not a standard DSP operation. I assumed that all blocks - it means: BPF, Descending..., LPF, FFT, and so on, are realized on discrete samples of signals r(t) and x(t), but this issue is not clearly stated in your paper.
Maybe you the "Descendign to complex..." block is a kind of digital down conversion (DDC) operation, which is a standard block in almost all digital receivers? If so, please change the name of this block.

* pg 7. par 16
Bellhop - is this software for modeling sound propagation in the ocean provided by a Norwegian university? If so, you should definitely put a reference to the manual or any paper describing the use of this software. I have no connection with the authors of this software, thus no conflict of interest.

* pg 9. par 21-23
"... the receiver moves from shadow to direct-arrival zone." - it is not clear to me how the receiver can move? according to Figure 2, only the transmitter can move. Moreover, I don't see any obstacles that could create a shadow zone. Maybe I'm not familiar with the high-frequency sound propagation in the deep ocean, but please explain how the shadow-zone can exist without obstacles?

* pg 18, par 6
"One the one hand ..." -> On the one hand ...

* The issue of the existence of a shadow zone in the measurements should be clarified.

Comments on the Quality of English Language

* There are still many spelling and grammar mistakes in the article.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf