Simulation-Based Selection of Transmitting Antenna Type for Enhanced Loran System in Selected Location

Round 1

Reviewer 1 Report

In my opinion, the article in the current version should be rejected.

The paper lacks a many elements:

• A very simple description of the antenna model is present in the paper. It should be more detailed in order to give to the reader a more precise overview of the prototype realized and tested by the authors.
• There is no description in the pictures of the antennas.
• There is no research methodology, simulation tools (environment), models, assumptions for simulation studies have been presented. This should be described in detail or given appropriate references.
• The description of the results is very poor. It can be said that there is no description. There is no clear analysis of the results obtained. The Authors should correct this. The Authors should explain the simulation results presented in detail.
• In chapter 4.1, 4.2, 4.3  there are almost only drawings without description - not allowed in articles.
• What is the novelty and contribution of the work. I did not see anything new or what the author has performed extra than current literature.
• This research has to be revised with some new input before being submitted for publication in the journal.

Author Response

Point 1: A very simple description of the antenna model is present in the paper. It should be more detailed in order to give to the reader a more precise overview of the prototype realized and tested by the authors.

 

Response 1: The relevant description of antenna has been added in this paper, so that readers can better understand the research purpose of this paper.(in red)

 

Point 2: There is no description in the pictures of the antennas.There is no research methodology, simulation tools (environment), models, assumptions for simulation studies have been presented. This should be described in detail or given appropriate references.

 

Response 2: The single tower and four tower antennas in this paper are structural diagrams, which aims to let readers understand the shape and structure of this type of antenna. The specific parameters are described in detail in this paper. So I didn't add a description to the picture. In addition, the project plan is still in the confidential stage, so it is not convenient to modify and explain it in the picture.

Detailed descriptions of research methods, simulation tools (environment), models, assumptions and results of simulation research have been added accordingly.(in red)

 

Point 3: In chapter 4.1, 4.2, 4.3  there are almost only drawings without description - not allowed in articles.

 

Response 3: Specific descriptions of relevant simulation diagrams in 4.1, 4.2 and 4.3 have been added.(in red)

 

Point 4: What is the novelty and contribution of the work. I did not see anything new or what the author has performed extra than current literature.

 

Response 4:The novel content and innovative description of this paper have been added in the appropriate place in the text.（in red）

Author Response File: Author Response.docx

Reviewer 2 Report

In this paper,  a single-tower umbrella antenna is proposed as a Transmitting Antenna Type for Enhanced Loran System. This paper is not well written as many technical information were missing and the novelty of this work is not clear. My comments can be summarised as below.

1. Authors should expand the word "LORAN" for its title and providing this in the place where it was first introduced.
2. In the "Abstract", Authors should provide the quantitative performance achievement of the proposed enhanced Loran transmitter antenna types. This information should further add into the "conclusion" of this paper.
3. In the "Introduction", Authors should provide the review of types of different Loran transmitter antenna in the latest published literatures or commercial systems. The review here is very superficial. It is not clear what are challenges in designing such an antenna. What are the features, i.e. operating frequency, impedance bandwidth, radiation characteristics, i.e. radiation patterns, linear/circular polarisation, gains, radiation efficiency ??
4. In Figure 1, it shows the Schematic diagram of a single-tower umbrella antenna model. The detailed geometry parameters should be given.  In table 1, how many wavelength of the Antenna height ??
5. In Figure 2, again, please provide the detailed geometry parameters of the four-tower inverted-cone antenna. How the geometry parameters in Table 2 relates to Figure 2 ??
6. In section 3, no reference were given here and the quality of the figures were poor. 
7. In section 4, it is not clear how the results from Figure 7 to Figure 14 were produced. Authors should provide the details of how the simulation were carried out ?? What environment conditions were assumed ?? What software were used ?? How authors verified their results. Very limited texts were given here to describe the results. 
8. The connection for all the sections, i.e. "1 Introduction", "2.Overview of Loran transmitting antenna", "3. Geographical characteristics of Loran-C transmitting antenna", "4. Estimation of antenna radiation field" in the paper is very difficult to understand. Authors need to enhance significantly on this. Otherwise, readers cannot understand what authors would like to explain their scientific achievements of their work. 

Author Response

Point 1: Authors should expand the word "LORAN" for its title and providing this in the place where it was first introduced.

 

Response 1: LORAN is long range navigation. The position that has appeared in the first article has been explained. (in red)

 

Point 2: In the "Abstract", Authors should provide the quantitative performance achievement of the proposed enhanced Loran transmitter antenna types. This information should further add into the "conclusion" of this paper.

 

Response 2: An equal amount of description has been added in the summary and conclusion sections.. (in red)

 

Point 3: In the "Introduction", Authors should provide the review of types of different Loran transmitter antenna in the latest published literatures or commercial systems. The review here is very superficial. It is not clear what are challenges in designing such an antenna. What are the features, i.e. operating frequency, impedance bandwidth, radiation characteristics, i.e. radiation patterns, linear/circular polarisation, gains, radiation efficiency ??

 

Response 3: It has been revised and re described according to the opinions of review experts.（in red）

 

Point 4: In Figure 1, it shows the Schematic diagram of a single-tower umbrella antenna model. The detailed geometry parameters should be given.  In table 1, how many wavelength of the Antenna height ??

 

Response 4: 

Explanation: Figure 1 is a schematic diagram of the shape of a single tower umbrella antenna. Because it is a schematic diagram, the reader is expected to understand the basic shape of the antenna. Therefore, there is no need to give the structural parameters here, because the structural parameters are also different according to different designs, so it is impossible to give specific fixed parameters. The antenna height in Table 1 is very clear. Since the enhanced Loran signal is a long wave signal, the antenna height is 1 / 10 wavelength, that is, between 100m and 300m. The specific performance changes with the height, and generally not many wavelengths are mentioned.

 

Point 5：In Figure 2, again, please provide the detailed geometry parameters of the four-tower inverted-cone antenna. How the geometry parameters in Table 2 relates to Figure 2 ??

 

 

Response 5: 

Explanation: Figure 2 is the schematic diagram of the four tower inverted conical antenna, which is mainly the same as the schematic diagram of a single tower. It is hoped that readers can understand the basic structure of the four tower antenna. No clear geometric parameters are given because different design schemes will have different parameter indexes, so it is impossible to give fixed parameters. The data in Table 2 is for readers to understand that different heights will affect all aspects of electrical parameters. At the same time, it is also a comparison with the electrical parameters of single tower antenna, so as to find out which form performance is more in line with the requirements.

The relationship between table 2 and Figure 2 has been described in the text.(in red)

 

Point 6: In section 3, no reference were given here and the quality of the figures were poor. 

 

Response 6: I'm very sorry for the picture quality of Part 3. The author obtained it through the screenshot of Google maps, and the text description of this part was written by the author himself after consulting the network materials. Therefore, there are no references, which have been marked at present.（in red）

 

Point 7: In section 4, it is not clear how the results from Figure 7 to Figure 14 were produced. Authors should provide the details of how the simulation were carried out ?? What environment conditions were assumed ?? What software were used ?? How authors verified their results. Very limited texts were given here to describe the results. 

 

Response 7: I'm very sorry for the picture quality of Part 3. The author obtained it through the screenshot of Google maps, and the text description of this part was written by the author himself after consulting the network materials. Therefore, there are no references, which have been marked at present.（in red）

 

Point 8: The connection for all the sections, i.e. "1 Introduction", "2.Overview of Loran transmitting antenna", "3. Geographical characteristics of Loran-C transmitting antenna", "4. Estimation of antenna radiation field" in the paper is very difficult to understand. Authors need to enhance significantly on this. Otherwise, readers cannot understand what authors would like to explain their scientific achievements of their work.

 

Response 8:The name of the chapter has been modified to better link up and down.（in red）

 

 

Author Response File: Author Response.docx

Reviewer 3 Report

Dear authors, the paper is interesting and presents an adequate analysis of the problem. I suggest to improve the quality of english language, revising sentences and grammar and a the quality of the figures, that seems stretched and/or low ppi images.

Author Response

Point 1: Dear authors, the paper is interesting and presents an adequate analysis of the problem. I suggest to improve the quality of english language, revising sentences and grammar and a the quality of the figures, that seems stretched and/or low ppi images

 

Response 1: Thank the review experts for their evaluation of my work. I have improved the picture quality and English grammar description, and added some descriptions, which makes the article more convincing.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

 

Most of the comments from the review were taken into account by the authors.

In my opinion, the article in the current version can be accepted after minor revision.

In the paper, correct a few elements:

• There is no description in the pictures of the antennas. Please add the tags in figures 1 and 2 as listed in tables 1 and 2.

• There are very old items in the bibliography. Is it possible to review and refer to newer literature. Update your bibliography with newer items.

• Improve the quality (resolution) of your drawings

Author Response

Response to Reviewer 1 Comments

 

Point 1:There is no description in the pictures of the antennas. Please add the tags in figures 1 and 2 as listed in tables 1 and 2.

 

Response 1: The main parameter labels of Table 1 and table 2 have been added in Figure 1 and Figure 2.

 

Point 2: There are very old items in the bibliography. Is it possible to review and refer to newer literature. Update your bibliography with newer items.

 

Response 2: Some new references have been updated, but some older references have been retained because they are really important to the article. Please review experts to understand, thank you!

 

Point 3: Improve the quality (resolution) of your drawings。

 

Response 3: The quality of all drawings has been improved accordingly.

Author Response File: Author Response.docx

Reviewer 2 Report

After the first round of review, although some of the comments have been addressed, but reviewer felt significant works are required before this paper can be considered to publish in this journal.

1. The verification of the presented simulated results from Figure 4 is rather weak. Also, the explanation of these results are very limited. What readers can learn from this ??

2. Very limited design concepts for the proposed antenna were given. How authors came out with such as design ?? It is still questionable what are the novelties/contributions of this work ??

3. Authors should summarise the performance achievement of this work comparing with other published works in the literature.

4. Authors should plot the radiation characteristics, i.e. patterns, gains, radiation efficiency etc. as well as the S-parameters performance of the antennas.

5. section 3, perhaps should be moved to section 2. 

 

Author Response

Response to Reviewer 2 Comments

Comments

 

Point 1: The verification of the presented simulated results from Figure 4 is rather weak. Also, the explanation of these results are very limited. What readers can learn from this ??

 

Response 1: Figure 4 is a physical diagram of several long wave transmitting antennas built in China in the past. This figure is to let the reader understand the basic form of the antenna. I have explained the simulation diagram in part IV of the article in more detail. The purpose is to let the reader understand the long wave signal transmission in Tibet and the transmission capacity of the transmitting antenna.

 

Point 2: Very limited design concepts for the proposed antenna were given. How authors came out with such as design ?? It is still questionable what are the novelties/contributions of this work ??

 

Response 2: The explanation of design reason of transmitting antenna is added. Readers can understand why the requirements for transmitting antennas are so strict. In addition, the relevant descriptions of innovation and contribution are added.(in red)

 

Point 3:  Authors should summarise the performance achievement of this work comparing with other published works in the literature.

 

Response 3: Achievements compared with references have been revised and added.

 

Point 4: Authors should plot the radiation characteristics, i.e. patterns, gains, radiation efficiency etc. as well as the S-parameters performance of the antennas.

 

Response 4: Graphics related to the radiation characteristics of the transmitting antenna have been added to better understand the radiation performance of the transmitting antenna.

 

Point 5：section 3, perhaps should be moved to section 2. 

 

 

Response 5: Chapter 2 has been exchanged with Chapter 3.

 

 

Author Response File: Author Response.docx

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

The manuscript “Selection of Enhanced Loran Signal Transmitting Antenna” focuses on a selection of transmitting antennas in the Enhanced Loran (eLoran) system. The topic is interesting and current, but the research materials’ presentation is inappropriate for a scientific article in the renowned MDPI Applied Sciences journal. Below, I will present the currency of this topic. The biggest drawback of the manuscript is its presentation form. In the bibliography, there are 23 references. However, in the text of the paper, no citation was made (i.e., any appropriate references were not cited). Thus, a potential reader should have to go through all the references to find the detail of interest. This is unacceptable. Besides, Introduction is too short, no text in some sections, not clear charts, no chart analysis, the template is not used in full. In my opinion, the article in the current version should be rejected. Significant revision is required before its publication. Below, I present suggestions and comments to help the Authors improve the manuscript.

 

Main disadvantages of reviewed manuscript:

1. Title

Generally, the manuscript title should reflect the aim and content of the paper. However, after reading the whole article, I got the impression that the purpose of the paper is the selection of transmitting antennas based on simulations for the selected location. So the title should be corrected, e.g., “Simulation-based Selection of Transmitting Antenna Type for Enhanced Loran System in Selected Location”. This is only my suggestion. Of course, the title does not have to be exactly as suggested, but it should better reflect the content of the article.

 

2. Simulations

Based on Conclusions and the description in the text (e.g. in the tables, in Section 4), I have the impression that the authors present the results of their simulation studies. However, no research methodology, simulation tools (environment), models, assumptions for simulation studies have been presented. This should be described in detail or given appropriate references.

 

3. Introduction

Introduction should consist of four main parts:

1. At the beginning there should be a short description to the general subject of the article - in this case, it's about navigation. In the case of journals whose scope is wide (such as the journals of the MDPI publishing house: Applied Sciences, Sensors, Electronics), this is particularly important for readers. The Loran system is not a familiar concept to people in other scientific disciplines, but the concept of navigation is fairly general. Then, after the first paragraph of Introduction, the reader knows what the article is about.
2. Next, the Authors should provide a more detailed description of the subject area.In this case, the development trends of, e.g., navigation systems should be described (see below). A detailed overview of different solutions, e.g. transmitting antennas for eLoran, can be moved to section 2 of the article, as did the Authors.
3. Against this background, the main topic in the paper should be presented. At this point, the currency of the topic, novelty, originality of the paper, and contribution (e.g., in relation to the earlier works of the Authors - if it is a continuation of research, previous works, or in relation to the current state of literature) should be emphasized. The Authors can also present their motivation, e.g., the topic of antenna selection is related to the newly developed eLoran broadcasting system, etc.
4. The final paragraph of Introduction may present the layout of the article – a brief description of what is included in each section.

Below, I show an example of how to justify taking up topics related to ground navigation, which in general perception may be a minor and outdated topic.

For 20 years, we have watched the worldwide availability and admiration of global navigation satellite systems (GNSSs). The halting of the development of other navigation systems primarily intended for sea and air transport, especially terrestrial (ground) systems, was an accompanying trend. At one point, even the maintenance of terrestrial systems as backup was abandoned [1]. However, the development of methods for jamming and spoofing GNSS signals reversed this trend a few years ago. More and more incidents, especially in the field of spoofing, concerned not only military systems but, above all, civilian ones [2]. Hence, nowadays, terrestrial navigation systems such as the eLoran are treated as backup systems that are being upgraded again. In addition, new solutions are being developed, especially for coastal marine navigation, e.g., [3–10].

I recommend mention other approaches for maritime navigation alternative to GNSS and eLoran, including, ranging-mode (R-mode) of the Automatic Identification System (AIS) [3,4], R-mode VHF Data Exchange System (VDES) [5,6], Doppler-based approaches [7,8], asynchronous hyperbolic AEGIR system [9], and other solutions [10,11].

In the case of eLoran, the Authors should present the development trends of this system, including in particular the improvement of signal processing, including Skywave delay estimation [12–15], or the use of the differential method for many transmitters [16,17], and other approaches, e.g., [18].

[1]     H. Kim, et al., Multi-Radio Integrated Navigation System M&S Software Design for GNSS Backup under Navigation Warfare. Electronics 2019, 8, 188. doi: 10.3390/electronics8020188

[2]     A. Androjna, et al., Assessing Cyber Challenges of Maritime Navigation. J. Mar. Sci. Eng. 2020, 8, 776. doi: 10.3390/jmse8100776

[3]     K. Zheng, et al., Positioning error analysis of ranging-mode using AIS signals in China, J. Sens. 2016, 2016, e6928961, 1–11. doi: 10.1155/2016/6928961

[4]     Q. Hu, et al., Development of an automatic identification system autonomous positioning system, Sensors 2015, 15, 11, 28574–28591. doi: 10.3390/s151128574

[5]     J. Safar, et al., Performance bounds for VDES R-mode, J. Navig. 2020, 73, 1, 92–114. doi: 10.1017/S0373463319000559

[6]     M. Wirsing, et al., Investigating R-mode signals for the VDE system, in Proceedings of OCEANS 2019, Seattle, WA, USA, 27–31 October 2019, pp. 1–5. doi: 10.23919/OCEANS40490.2019.8962635

[7]     C. Ziolkowski, et al., Doppler-based navigation for mobile protection system of strategic maritime facilities in GNSS jamming and spoofing conditions, IET Radar Sonar Navig. 2020, vol. 14, 4, 643–651. doi: 10.1049/iet-rsn.2019.0413

[8]     J. M. Kelner, et al., Reserve navigation system for ships based on coastal radio beacons, in Proceedings of 2016 IEEE/ION Position, Location and Navigation Symposium (PLANS), Savannah, GA, USA, 11–14 April 2016, pp. 393–402. doi: 10.1109/PLANS.2016.7479726

[9]     S. J. Ambroziak, et al., Ground-based, Hyperbolic Radiolocation System with Spread Spectrum Signal - AEGIR, TransNav – Int. J. Mar. Navig. Saf. Od Sea Transp. 2011, 5, 2, 233–238.

[10]   S. Kavuri, et al., Performance analysis of onshore NB-IoT for container tracking during near-the-shore vessel navigation, IEEE Internet Things J. 2020, 7, 4, 2928–2943. doi: 10.1109/JIOT.2020.2964245

[11]   A. Bhardwaj, Terrestrial and Satellite-Based Positioning and Navigation Systems—A Review with a Regional and Global Perspective. Eng. Proc. 2020, 2, 41. doi: 10.3390/ecsa-7-08262

[12]   K. Zhang, et al., Skywave delay estimation in Enhanced Loran based on extended invariance principle weighted Fourier transform and relaxation algorithm, IET Radar Sonar Navig. 2019, 13, 8, 1344–1349. doi: 10.1049/iet-rsn.2018.5651

[13]   K. Zhang, et al., Enhanced Loran skywave delay estimation based on artificial neural network in low SNR environment, IET Radar Sonar Navig. 2020, 14, 1, 127–132. doi: 10.1049/iet-rsn.2019.0222

[14]   J. Yuan, et al., Demodulation Method for Loran-C at Low SNR Based on Envelope Correlation–Phase Detection. Sensors 2020, 20, 4535. doi: 10.3390/s20164535

[15]   W. Yan, et al., Precise Loran-C Signal Acquisition Based on Envelope Delay Correlation Method. Sensors 2020, 20, 2329. doi: 10.3390/s20082329

[16]   Y. Li, et al., Research on the eLoran Differential Timing Method. Sensors 2020, 20, 6518. doi: 10.3390/s20226518

[17]   B. Yan, et al., High-Accuracy Positioning Based on Pseudo-Ranges: Integrated Difference and Performance Analysis of the Loran System. Sensors 2020, 20, 4436. doi: 10.3390/s20164436

[18]   C. Yang, et al., Experimental Study of a Signal Modulation Method to Improve eLORAN Data Channel Communications. Sensors 2020, 20, 6504. doi: 10.3390/s20226504

 

4. Template

The Authors must carefully follow the guidelines according to “Instructions for Authors” provided on the website:

https://www.mdpi.com/journal/applsci/instructions

and follow the formatting given in the template in detail:

https://www.mdpi.com/files/word-templates/applsci-template.dot

The main errors concern, i.a.:

1. formatting captions of sections, subsections, figures, tables,
2. formatting tables, references,
3. lack of reference citations in the text,
4. no mandatory sections after Conclusion and before References, i.e., Supplementary Materials, Author Contributions, Funding, Institutional Review Board Statement, Informed Consent Statement, Data Availability Statement, Acknowledgments, and Conflicts of Interest (see template).

 

5. Other suggestions:

1. Please present the figures after their reference in the text, e.g., Figures 1 and 2 are before. Please check out the others.
2. The caption of Figure 1 is on the next page than the figure.
3. The description of the antennas includes the "height" parameter and in the tables - "effective height". Is it the same? If so, why the description in words is inconsistent with the table, e.g. "The single-tower antenna is usually an umbrella antenna supported by a 200–300-m-high tower. ...", and in Table 1 effective height is equal {189, 168.1, 124.4} (m), i.e., effective height is smaller than 200m, and in Section 3, this antenna type could have more than 400m. For the next antenna type is similar. Please correct these incoherences.
4. The captions of subsections 2.1. and 2.2. are the same.
5. The number of Table 2 is incorrect – please see the template.
6. The Authors wrote that the parameters in Tables 1 and 2 were obtained “via theoretical simulations and equal-scale reduction experiments”. Please describe the simulation tool (environment, program) and simulation method, or cite relevant papers. For “simulations”, it is better not to use the word “theoretical”.
7. In Section 3.1, the BPL abbreviation is not explained. Please introduce its full name.
8. From Section 3, please do use Figure instead of the Fig abbreviation.
9. In Section 4, please improve the units “dBV∙m-1∙Hz1/2” – maybe, it will be better, e.g., “dBV/m∙Hz^1/2”. Please correct the others.
10. In Section 4, the Authors wrote “… By estimating the transmission field strength of the antenna in four directions …”. Please describe the methodology of estimation field strength. How did the Authors consider the influence of the terrain (landform) in the analyzed directions on the estimation of the field strength (i.e., path loss)? What path loss model, simulation tool, etc., are used?
11. I suppose the figures in Sections 4.1-4.4 are for the four analyzed directions, which are described in Section 4. Why do I have to guess this? There is no reference to these figures in the text. In Sections 4.1-4.4 there is no text, only figures. This is the first time that I have experienced such an approach. There is no clear analysis of the results obtained. The Authors should correct this.
12. Figures 7-14 have a varied style. The Authors should standardize the description of the axis and scale. I suggest using the font "Palatino Linotype" Size 10 as in the text. The description of the axis in some figures is blurry.
13. The analysis under Figure 14 probably applies to all Figures 7–14. In the present case, the application of subsections 4.1-4.4 means that this text can only be referred to Section 4.4.
14. Conclusion – The purpose of the article has just been outlined in Conclusion. In Introduction, the Authors should also present Certain issues shown in Conclusion.
15. No work (cited sources: journal/conference paper, book, report, website, etc.) may be introduced in References unless explicitly cited in the paper. Currently, none of the references have been cited. This approach is unacceptable.

Comments for author File: Comments.pdf

Reviewer 2 Report

In my opinion, the article is unacceptable.

The paper lacks a several elements.

• A very simple description of the antenna model is present in the paper. It should be more detailed in order to give to the reader a more precise overview of the prototype realized and tested by the authors.
• The description of the results is very poor. It can be said that there is no description. Explain the simulation results presented in detail. In chapter 4.1 there are only drawings without description - unacceptable in articles.
• What is the novelty and contribution of the work. I did not see anything new or what the author has performed extra than current literature.
• No comments on the simulation results presented.
• The published literature is old. You can cite many newer papers published on the topic presented.
• This research has to be revised with some new input before being submitted for publication in the journal.