Range Deception Jamming Performance Evaluation for Moving Targets in a Ground-Based Radar Network

Round 1

Reviewer 1 Report

The coordinate transform is well described as basis for the further investigation to achieve the track fusion.

Figure 6 gives a good example of no fusion matching.
However, in Figure 8 and 9 it is difficult to distinguish the yellow and green lines. 
Mainly the red track is visible and only partially green is visible. A question comes up to me: Is the false target credible at all if only a part of the track (in time) fullfills the fusion criterion?
In 9a) it says the fusion rate is 82%, but not 82 % of the red track is overlappng witrh the green one. In 9c) and d) it seems, that the fusion criterion is fulfilled, even though, the red track has stopped before.

Please, explain the numbers in Equ. (31) referring to Figure 7

Some editing or spelling:
line 12 and 31 'four(-)anti-resistance..'

end of line 36: should read 'electronic deception' not 'detection'?

line 47: 'due to the fact'

line 186: k and Ai are not used in equ.11, only k in equ.12

Table 1: What does 'azimut size' means,   angular resolution?

From Figure 6 on, the '.' is behind 'Figure' not behind the number.

line326 'can see that, the'  comma on wrong place.

Between line 383 and 384 insert empty line to separate figure caption. As well as before/after some of the following tables.

As a further investigation, maybe a formula to find the range delay boundary can be derived, now it is an estimation, e.g. 'between 10-20km' according to the simulation runs.

General remark: In my opinion, one of the critical parameters for this investigation is the size of the radar's range resolution cell which is kept constant in this paper (assuming 1MHz radar bandwidth).

 

Author Response

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Reviewer 2 Report

1. The work has an overview character in the first part. This is justified - it is an introduction to the computational part.

2. The experiment appears to have been constructed correctly, according to the rules of the art. But I think it will good to explain configuration of analysed situtaion, especially why we have three radars (why not four or five? In section 4 authors show results for three radars systems and four radars systems.)

3. The figures are clearly and good quality. But maybe Figure 6 could be improved. 

4. Conslusions (section 5) are too short. I think it should be expanded.

5. The References are good. But half of sources are older than ten years. 

6. The text contains a number of small errors or imprecised terms. Especially:

a. The table 2: Radar peak power: 150kw instead 150 kW

b. in many places: authors don't separate value and units, it should be corrected

c. line 92 (and rest of the paper): For the sth radar - it is not clear. What is it : sth - something? If it is element from network may be formula s-th radar will better, maybe italic?

d. line 120 (and rest of the paper): what denotes H - it is height of the radar (in sense size of the radar) or height of the land above sea level (or relative height of the land) of the place where radar is situated?

e. line: 156 (and rest of the paper): Equ. (1) - better form I think is Equation (1).

f. line 186 (and rest of the paper) : sometimes is ith sometimes ith (all or not all is italic). Try to unify signs.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

General comments

1.       The main strategy of the jamming used in the paper is not introduced. It is not clear what exactly the jammer tries to do: ‘create’ the illusion of the fake target at particular point or disturb the system performance anyhow.

2.       The introduced signal model is rather specific. Thus, it can only be guessed that the transmitted signals are linear chirp signals. Moreover, the model of received signals does not include such important points as Doppler shift and the receiver antenna radiation pattern, especially its phase.

3.       The multistatic radar system, which is the network of several radar stations, is not properly described. For instance, it is not clear, whether all the radar stations emit and receive the signals or there is only one station emitting the signal while the other are just receivers. If each station emits its own signal (e.g., the authors’ example in Table 4), how can the jammer reemit the same signal with the same additional delay?

4.       No sooner had it come to the almost end of the simulation section than the main idea was properly explained! Figure 10 should definitely support the explanation written in lines 124-128. Unfortunately, having taken all those pieces together, it becomes clear that the proposed jamming scheme is doomed to be not working properly from the very beginning. The jammer is described as the system, which omnidirectionally transmits the modified copy of the signal it has intercepted. Hence, the signal will be received by all radar stations. At this point, the fact that the scheme is impractical becomes obvious, since each radar can be somehow deceived only if it has received the signal with the delay tailored specifically for it. Indeed, the common delay injected in the signal will definitely produce separate tracks. And it is only the noise that can mix them up. Even worse, the position of such a jammer can be deduced as soon as the number of radar station is big enough.

5.       There is no comparison with other jamming schemes. Discussion section is highly welcomed.

6.       The paper is not properly structured. Section 2 seems to be redundant since it is mainly repeated in Subsection 3.2. It could be better to merge them and put it in the right place in the narration. 

Particular remarks

1.       Describing the simulation examples, the authors have omitted the essential information about the coordinate of the point where the jammer is. The sketch of the networks will also be very useful for better understanding. The main issue here is that the position of the jammer is crucial here. For instance, if we take into consideration three-radar case, those stations will form the triangle. The overall performance will significantly depend on the type of that triangle (equilateral, right, or obtuse) and where the jammer is with respect to the projection of that triangle onto the earth surface.

There is a classical paper doi: 10.1109/TAES.1984.310439, where the main concept of measuring radar performance is well-established. Since the radar systems receiving a jammer signal is very similar to the passive case, it will suit well.

2.       Subsection 3.4 shows a developed authors’ skill of doing high school trigonometrical exercises. That also helps them fill almost three pages with monotonous formulae but does not leave the reader a clue how all that can be generalized for the case where more than two radar stations are involved.

3.       Figures 4, 6, 8, 9 shows the results in some coordinate system. What is that coordinate system? How has it been chosen?

4.       The results shown in fig. 7 (b) for the slant range looks rather doubtful since the line turns into the perfect constant after some point. In contrast, the plot in fig. 7 (a) does not show the same pattern.

5.       What are the units for numbers in (31)?

6.       In lines 96-97, the parameter γ seems to be wrongly defined (how could it be ‘the range frequency rate’?) while f_с is not defined at all.

7.       The example in Table 6 does not correspond to the vertices of a rectangle as it is claimed in line 431. Please, revise spherical geometry.

8.       The list of acronyms is highly welcomed (DFRM, RCS, etc.).

9.       Some terms are misguiding, e.g., the boundary conditions, delay boundary.

10.    Some terms are not explained, e.g., the fusion rate (in line 369).

11.    The self-invented term for operator describing the variance (26, 31) looks revolting. 

Language

The language is of moderate quality. However, yet another accurate proofreading is necessary. 

Summary

The paper contains serious conceptual and methodological flaws. However, the results may be interesting for readers provided that the authors correct their main mistakes, add clear and explaining description of what they actually did and point out the limitation of their approach and models.

 

Author Response

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Author Response File: Author Response.pdf

Reviewer 4 Report

Interesting and well-presented work. The study presents a theoretical analysis without confirmation of practical results. The study seems well-conducted and makes a valuable contribution to the field.  Here are some suggestions for improving your work.

1)      Regarding the text presented, there are a lot of typos and writing.

a.There are several mistakes of space before/after commas. I suggest careful checking before it is published.

b. In almost all equations, punctuation is missing.

2)      There is also a problem with the size of the formulation and text fonts

3)      The quality and description of all figures could be improved.

4)      Figures could be centralized.

5)      Figs. 3, 7: font size

 

6)      Figs. could be better described and explained.

Author Response

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Reviewer 5 Report

 1.      This paper evaluates the range deception jamming performance for moving targets in a ground-based radar network. The paper provides useful information and the results are satisfactory.

2.      The writing of the paper needs improvement. There are some grammatical errors and mistakes. Also some clarifications are needed. As listed below.

3.      Lines 84-88, change Section II, III, IV and V to 2 - 5 to be consistent with the section numbers in the paper.

4.      Line 96, a (tm ) is not in Equation 1. Please define j, c and f_c in Equation 1.

5.      Line 102, "pass though" should be "through"?

6.      Some symbols in Eqn. 2 are not defined.

7.      In Fig. 1, it is suggested to present the coordinate system in 3D to be compatible to the text.

8.      Line 185, k and Ai are not in Equation 11. All the symbols in equations 11 and 12 should be defined.

9.      In Fig. 5, add necessary condition assessment such as "No".

10.   Fig. 9 title, "30km", "40km" add a space between the number and km. Make changes accordingly in other places.

11.   In Table 4, change m2 to m²

12. Please add more specific information in Conclusions so the reader can get sufficient information by reading it.

Author Response

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Round 2

Reviewer 3 Report

 I must notice that the authors have done a great job improving their paper responding to the comments given by me and other reviewers.

I would recommend incorporating most of the explanation in Response 1 to my general remarks, including the Figure, into the paper. The Figure given in Response 7 to my specific remark is also recommended for the inclusion in the paper as it will greatly explain the geometry of the system.

However, the unexpected behavior of the curve in Figure 7 (b) “RMSE of slant range versus target RCS” has not been explained at all. Instead, the authors repeated that it had been obtained via the Monte-Carlo experiments. The fact that a single curve flattens may whiteness about either an additional non-linear step in the algorithm or some mistakes. Otherwise, it requires to be explained especially one can see that, in contrast, the other curve, in Figure 7 (a), does never get flat.

Author Response

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