Multi-Radio Integrated Navigation System M&S Software Design for GNSS Backup under Navigation Warfare
Round 1
Reviewer 1 Report
The idea of combining diverse sources of localization, for avoiding effects of hostile interference/attacks, in particular to GPS resources is a highly relevant topic. The paper is very interesting in that sense.
The structure of the software makes good sense.
1) M&S should be defined in the first lines of the paper.
2)
Something which is missing in the paper, is a description of the approaches used for the sensor data fusion, which allows the detection of the inconsistencies of certain sources.
I presume some approach was used in the simulations.
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3) are the simulations realistic enough?
3.1) give more details about the type of noise being simulated (added to the nominal measurements)
is that noise GWN? is that consistent with the uncertainty introduced by a hostile intrusion?
Author Response
Reviewer 1
The authors appreciate for reviewing our manuscript. Due to the comments, the completeness of our manuscript has been improved. The authors wish that the revised version of our manuscript would be satisfactory to the reviewer.
Comment 1:
M&S should be defined in the first lines of the paper.
Response:
The M&S were defined in the first lines of the manuscript as the reviewer suggested.
The simulation is defined as the imitative representation of the functioning of one system or process by means of the function of another and the modeling is defined as producing a representation or simulation [1].
Comment 2:
Something which is missing in the paper, is a description of the approaches used for the sensor data fusion, which allows the detection of the inconsistencies of certain sources. I presume some approach was used in the simulations.
Response:
A more detailed description on the approach for the sensor fusion and effect of jammer to GPS measurement are added in section 4.
For the multi-radio integrated navigation system, the weighted least square method was used. The weights were determined from the measurement error statistics listed in Table 5. It was assumed that the jammer influenced only the GPS signals. When the J/S is larger than 40 dB, the measurement is not available since the signals cannot be tracked in this environment. When the J/S is less than 40 dB, measurement error caused by the jammer is added to the measurement.
Comment 3:
Are the simulations realistic enough? 3.1) give more details about the type of noise being simulated (added to the nominal measurements) is that noise GWN? is that consistent with the uncertainty introduced by a hostile intrusion?
Response:
The simulations are realistic even though the error model is simple.
Yes, the type of the noise in the simulation is WGN (White Gaussian Noise). The measurement errors listed in Table 5 were referenced from text books and operating manuals of the navigation systems.
It was assumed that other errors except the WGN were compensated in the receiver. In the manuscript, to show the feasibility of the proposed M&S S/W design method, these simple simulation results were presented. It is possible to simulate the performance of the navigation algorithm for other errors of the navigation systems. In this case, the errors are uncompensated parts by the receiver and can be generated in the navigation environment generation part of the M&S S/W.
The type of the noise is described in Section 4 as follows
Measurement errors of the navigation systems in the performance evaluation were assumed to be white Gaussian noise and their standard deviations are listed in Table 5
Reviewer 2 Report
Manuscript: Electronics-422909
Title: Multi-radio Integrated Navigation System M&S Software Design for GNSS Backup under Navigation Warfare.
Authors: Heyone Kim; Junhak Lee; Sang Heon Oh; Hyoungmin So; Dong-Hwan Hwang
Description: In this manuscript authors presents a multi-radio integrated navigation system (M&S) that can be used to recover from degradation of navigation performance in the navigation warfare environment, moreover in the proposed M&S all available radio navigation systems are integrated in order to backup GNSS. Software schemes and GUI are presented.
In general a moderate revision of the English Language is needed to clarify some sentences. I suggest moreover to reduce the number of Figures (22) and tables if possible.
In the title I don’t know if it is the case of indicate acronym M&S, the title seems more clear without it. i. e. Multi-radio Integrated Navigation System M&S Software Design for GNSS Backup under Navigation Warfare.
The Abstract is too large (1576 characters) and needs to be summarised in fact the first sentence (rows: 16-17-18) of the abstract is repeated similar in the introduction at rows 43-44.
In particular:
1) Rows 43-44 - The sentence is copied and cut from the abstract, remove from the abstract.
2) Row 75 - The word Resutls must be replaced by Results.
3) Row 101 – Figure 1 – In the central box the writes are too little, the font needs to be enlarged to be visible to the reader.
4) Row 107 – Figure 2, In the central box of the figure (Gap Filling) is lacking the colour scale and in the caption authors should explain better what it is represented in the Figure.
5) Row 117 - In Figure 3 a strange font is used that isn’t easily readable, the style of the Figure can be improved.
6) Rows 121-122. The reason of the usage of a message broker is in my opinion also to improve the resolution of different components the signal can be divided, authors can explain better this important concept.
7) Row 141 – The beginning sentence needs to be clarified/enlarged “The procedure conducts function of the software”, a moderate revision of the English is necessary.
8) Row 159 – I think this Figure is not clear to be interpreted by the readers, I suggest the authors to choose the figures and the tables that are strictly necessary, in fact in this manuscript there are 22 figures, are all necessary? Less Figures better styled.
9) Rows 224 to 230 – In Figures 15 it is necessary to translate in English the boxes in the right lower part.
10) Rows 246-247 – The sentence “The vehicle takes off ….” Needs to be improved (English revision).
11) Rows 272 to 274 – The sentence is repeated.
12) Rows 295 to 299 – Figure 20, it is not clear why the noise level of the vertical component of GNSS is comparable with the noise level of the North one. Moreover and in general the vertical channel is labelled as Up and not Down (See axis labels).
13) Rows 304-305 – Table 7, in the fourth raw of the Table at 50W jammer power the GPS signal is lacking in the time range 2000-3500 sec (see Figure 22) nevertheless in the table 7 errors of GPS positioning are presented as little than errors of M&S. Authors should explain better the reason.
Author Response
Reviewer 2
The authors appreciate for reviewing our manuscript. Due to the comments, the completeness of our manuscript has been improved. The authors wish that the revised version of our manuscript would be satisfactory to the reviewer.
Comment 1:
In the title I don’t know if it is the case of indicate acronym M&S, the title seems more clear without it. i. e. Multi-radio Integrated Navigation System M&S Software Design for GNSS Backup under Navigation Warfare
Response:
The purpose of the manuscript is not multi-radio integrated navigation algorithm only but the whole M&S S/W design method. “Multi-radio Integrated Navigation System M&S Software Design for GNSS Backup under Navigation Warfare” would be more appropriate since the M&S S/W includes vehicle motion, navigation signal sources information, and navigation signal transmission characteristics.
Comment 2:
The Abstract is too large (1576 characters) and needs to be summarized in fact the first sentence (rows: 16-17-18) of the abstract is repeated similar in the introduction at rows 43-44.
Response:
The abstract was reduced as the reviewer suggested.
Comment 3-1):
Rows 43-44 - The sentence is copied and cut from the abstract, remove from the abstract.
Response:
The sentence was removed from the abstract.
Comment 3-2):
Row 75 - The word Resutls must be replaced by Results.
Response:
The word was replaced by Results.
Comment 3-3):
Row 101 – Figure 1 – In the central box the writes are too little, the font needs to be enlarged to be visible to the reader.
Response:
Actually, Figure 1 was deleted as suggested in the comment 3-8).
Comment 3-4):
Row 107 – Figure 2, In the central box of the figure (Gap Filling) is lacking the colour scale and in the caption authors should explain better what it is represented in the Figure.
Response:
Actually, Figure 2 was deleted as suggested in the comment 3-8).
Comment 3-5):
Row 117 - In Figure 3 a strange font is used that isn’t easily readable, the style of the Figure can be improved.
Response:
The strange font in Figure 1 has been changed.
Comment 3-6):
Rows 121-122. The reason of the usage of a message broker is in my opinion also to improve the resolution of different components the signal can be divided, authors can explain better this important concept.
Response:
The reason of the usage of a message broker suggested by the reviewer was added in the manuscript.
As shown in Figure 2, the message broker-based software consists of the message broker and the function modules. All the messages are transferred through the message broker in order to be exchanged between function modules. A complex function with large size can be easily divided into several modules and the function modules can be connected through the message broker. The message broker has all I/Fs (Interfaces) of function modules. The function module has only one I/F to exchange data with other function modules. Due to the message broker, each function module need not contain all the I/Fs.
Comment 3-7):
Row 141 – The beginning sentence needs to be clarified/enlarged “The procedure conducts function of the software”, a moderate revision of the English is necessary.
Response:
The sentence was revised as the reviewer suggested.
The procedure is the program code of function module of the M&S software.
Comment 3-8):
Row 159 – I think this Figure is not clear to be interpreted by the readers, I suggest the authors to choose the figures and the tables that are strictly necessary, in fact in this manuscript there are 22 figures, are all necessary? Less Figures better styled.
Response:
Figure 7, Table2, Table3 and Table 4 (in the reviewed manuscript) was revised to be interpreted by the readers. In addition to this, some sentences were added to the manuscript for the normal operation of Figure 6.
When the M&S program starts, the program is in the initialization mode. If the function module parameters are available, the program is in the stand-by mode. Then it is in the coverage analysis mode, the measurement generation and the navigation mode or the navigation only mode according to the condition.
As suggested by the reviewer, one Table and Four figures were removed.
Comment 3-9):
Rows 224 to 230 – In Figures 15 it is necessary to translate in English the boxes in the right lower part.
Response:
The box was translated in English.
Comment 3-10):
Rows 246-247 – The sentence “The vehicle takes off ….” Needs to be improved (English revision
Response:
The two sentences were removed. The authors think that the readers can easily understand what the authors would like to describe without the two sentences.
Comment 3-11):
Rows 272 to 274 – The sentence is repeated.
Response:
The repeated sentence was removed.
Comment 3-12):
Rows 295 to 299 – Figure 20, it is not clear why the noise level of the vertical component of GNSS is comparable with the noise level of the North one. Moreover and in general the vertical channel is labelled as Up and not Down (See axis labels).
Response:
When there is no jammer i.e. jamming power is 0 W, the vertical error is one and half times than the horizontal error in Table 6. This result is 95 % statistic value of Figure 15. This result agrees with the well-known fact that VDOP is one and half to two times than HDOP in GPS. It can be observed in Figure 15 that the north error is larger than the east error. This result is caused by the characteristic of the trajectory in which the vehicle moves from South to North. The vertical channel is labeled as down since the authors used the NED frame in the simulation.
Comment 3-13):
Rows 304-305 – Table 7, in the fourth raw of the Table at 50W jammer power the GPS signal is lacking in the time range 2000-3500 sec (see Figure 22) nevertheless in the table 7 errors of GPS positioning are presented as little than errors of M&S. Authors should explain better the reason.
Response:
In the navigation error calculation, since the reason is that the navigation error is not included in the calculation when the number of satellites in view is less than four or PDOP is greater than 10.
Similarly, the followings are described for the results the second and third columns of Table 6.
It can be observed from the results of GPS only navigation in Table 6 that the position errors increase as the jammer power increases from 0 to 50 W and decreases at 100 W. This decrease is caused by the fact that the navigation error is not included in the calculation when the number of satellites in view is less than four or PDOP is greater than 10.
Round 2
Reviewer 2 Report
The paper has been improved by authors taking into account all my indications and now seems to be ready for publication on MDPI Electronics. Nevertheless I suggest some minor corrections in the Figures 11, 12.
1) Row 217 - Figure 11 – The label of the key box closer to “SAVE” at the right is still in original language and not in English.
2) Row 225 – Figure 12. The Legend and all the labels of the Station Map box are too little to be readable. Difficult to be appreciated. Can the authors please enlarge them?
See the pdf enclosed.
Comments for author File: 
Comments.pdf
Author Response
The authors appreciate the reviewer for his comments.
The followings are point-by-point responses to the reviewer's comments.
1) Figure 11 was revised as the reviewer suggested.
2) Figure 12 was revised as the reviewer suggested.
