Receiving Paths Improvement of Digital Phased Array Antennas Using Adaptive Dynamic Range
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsComments to the Author
Please address the following comments
1. Define ADC in line 58, Section 1.
2. Define the terms accrued in Figure 1, such as f0, LO, LNA, I, CLK, SPI….(You defined some of them in Figure 2, however you should define them in the first appearance.
3. Explain Figure 1 and Figure 2
4. In Section 2, line 112, explain how you got the values for v=0.55/0.82? or its range value from 0.55 to 0.82 correct it, please
5. In Section 2, What is the difference between Pint.noise in equation 2 and Pinter.noise in line 123
6. In Section 1, lines 35-36, correct the reference format where the number of chapter for each reference should be added to bibliography not within the refence in the text. The line should be ended with full stop not a comma.
7. In Section 1, lines 52,55 correct the reference format [8¸12], [8¸10], Section 2, lines 162, 167, Section 3, lines 225, 228 , 292 you put a division mark?
8. In Section 2, Again you made the same mistake regarding the range in Table 1, you used a division mark. Correct it
9. In Section 2, equation 5, is it DTN or DTM, please check
10. In Section 3, equation 6, logarithm symbol should be written as log not lg
11. In Section 3, Why in Fig. 3 is Ulow.thres, Uup.thres however in the text they are Ulow.tres, Uup.tres , are they different please check
12. In Section 3, Correct the position of Fig.3, it should not be overlapped with the text
13. In Section 3, Line 235, correct the reference format
14. In Section 3 what is [V]? is volt unit? Define it first.
15. In Section 4, Correct the position of Fig.6, it should not be overlapped with the text
16. Make one format for the tables, Table 1 is different from others
17. Don’t mention any figures, tables, or references in the conclusion
Comments for author File: 
Comments.pdf
Author Response
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Comments 1: Define ADC in line 58, Section 1. |
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Response 1: Thank you for pointing this out. We agree with this comment. => (e.g., of the analog-to-digital converter (ADC)) |
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Comments 2: Define the terms accrued in Figure 1, such as f0, LO, LNA, I, CLK, SPI….(You defined some of them in Figure 2, however you should define them in the first appearance. |
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Response 2: Thank you for pointing this out. We agree with this comment. Figure 1. The general structure of the digital receiving model. f0 — carrier frequency; LNA — low-noise amplifier; LO — local oscillator; CLK — clock controller signal; ADC — analog-to-digital converter; SPIADC — serial peripheral interface of ADC; DSP — digital signal processor; SPIDSP — serial peripheral interface of DSP; and Dout — digital signal at the output. Comments 3: Define the terms accrued in Figure 1, such as f0, LO, LNA, I, CLK, SPI….(You defined some of them in Figure 2, however you should define them in the first appearance Response 3: Thank you for pointing this out. We agree with this comment. Of these, the analog part is typically synthesized according to the superheterodyne model (Figure 1). Figure 1. The general structure of the digital receiving model. f0 — carrier frequency; LNA — low-noise amplifier; LO — local oscillator; CLK — clock controller signal; ADC — analog-to-digital converter; SPIADC — serial peripheral interface of ADC; DSP — digital signal processor; SPIDSP — serial peripheral interface of DSP; and Dout — digital signal at the output.
Figure 2 illustrates the fundamental structure of the receiving path in the DTM. Figure 2. The fundamental structure of the receiving path in the DTM. QDM — quadrature demodulation; LNA — low-noise amplifier; IF Amp — intermediate-frequency (IF) amplifier. Comments 4: In Section 2, line 112, explain how you got the values for v=0.55/0.82? or its range value from 0.55 to 0.82 correct it, please Response 4: Thank you for bringing to our attention the inaccuracy in the range of quantitative values for the reference parameter, "coefficient of the antenna open surface area." It’s range value from 0.55 to 0.82. Upon review, including consultation of relevant sources such as antenna textbooks and published documentation, we have verified the correct range of values for this parameter. To enhance the rigor and clarity of the paper, we propose the following revision: The first, with regard to the parameter's name and value interpretation: "coefficient of the antenna open surface area" will be replaced with "coefficient of the aperture efficiency". The correct range for this parameter is v = 0.6 to 1.0 (reference: https://www.radartutorial.eu/06.antennas/Antenna%20Characteristics.en.html. last updated September 28, 2024). The second, in the context of the paper, this parameter is presented as a reference and is not used in subsequent analysis, ensuring that the scientific content remains unaffected. Comments 5: In Section 2, What is the difference between Pint.noise in equation 2 and Pinter.noise in line 123 Response 5: Thank you for pointing this out. We agree with this comment. Both Pint.noise and Pinter.noise are used to mean the same thing. We choose one and use it consistently – Pinter.noise. Comments 6: In Section 1, lines 35-36, correct the reference format where the number of chapter for each reference should be added to bibliography not within the reference in the text. The line should be ended with full stop not a comma. Response 6: Thank you for pointing this out. We agree with this comment. => [4–6]. Comments 7: In Section 1, lines 52,55 correct the reference format [8¸12], [8¸10], Section 2, lines 162, 167, Section 3, lines 225, 228 , 292 you put a division mark? Response 7: Thank you for pointing this out. We agree with this comment. A division mark is corrected. => [10–12]. Comments 8: In Section 2, Again you made the same mistake regarding the range in Table 1, you used a division mark. Correct it Response 8: Thank you for pointing this out. We agree with this comment. Table 1. The results of qualitative estimation of , , and .
Comments 9: In Section 2, equation 5, is it DTN or DTM, please check Response 9: Thank you for pointing this out. We agree with this comment. => Comments 10: In Section 3, equation 6, logarithm symbol should be written as log not lg Response 10: Thank you for pointing this out. We agree with this comment. => Comments 11: In Section 3, Why in Fig. 3 is Ulow.thres, Uup.thres however in the text they are Ulow.tres, Uup.tres , are they different please check Response 11: Thank you for pointing this out. We agree with this comment. The upper and lower threshold voltages, and , respectively. We choose them and use it consistently Comments 12: In Section 3, Correct the position of Fig.3, it should not be overlapped with the text Response 12: Thank you for pointing this out. We agree with this comment. Figure 3. To determine the dynamic range for the analog part of the receiving path (a), and the adaptive adjustment of the operating point position (b). Comments 13: In Section 3, Line 235, correct the reference format Response 13: Thank you for pointing this out. We agree with this comment. => [21] Comments 14: In Section 3 what is [V]? is volt unit? Define it first. Response 14: Thank you for pointing this out. We agree with this comment. [V] = Volt Comments 15: In Section 4, Correct the position of Fig.6, it should not be overlapped with the text Response 15: Thank you for pointing this out. We agree with this comment. Figure 6. The simulation procedure. Comments 16: Make one format for the tables, Table 1 is different from others Response 16: Thank you for pointing this out. We agree with this comment. Table 1. The results of qualitative estimation of , , and .
Comments 17: Don’t mention any figures, tables, or references in the conclusion Response 17: Thank you for pointing this out. We agree with this comment. 5. Conclusions This study addresses the challenge of improving the structure of the receiving path in the DTMs of modern DPAA systems to improve the detection of objects with low RCSs, which are inherently difficult to detect. Through a comparative analysis supported by qualitative calculations, we propose a novel approach to modify the receiving path structure, transitioning from an optimal filtering model to a fully matched filtering model. To achieve this, the concept of dynamic range in the receiving path is adapted to scenarios where the signal levels from such objects are significantly lower than the internal noise levels. The results have created the premise for the proposal of “pseudo-expansion” of the linear gain range of the analog part of the receiving path. The improvement has allowed for a reduction in the amplitude errors and phase errors of the low signals reflected from objects with low RCSs, as demonstrated by the simulation results. This enhancement leads to improved signal accumulation, thereby increasing the signal-to-noise ratio () at the input of the digital detector of the radar system. Under optimal conditions, where intermodulation distortion noise between DTMs is minimized, the value has the potential to approach the value of . It is important to note that the detection of low RCS objects remains a significant challenge, necessitating the integration of various approaches for an effective solution. Among these, the improvement of the receiving path structure, as proposed in this paper, offers a promising approach that should be considered and applied in the research and design of modern multifunctional radar systems to ensure the capability to detect a wide range of object types.
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Author Response File: 
Author Response.docx
Reviewer 2 Report
Comments and Suggestions for AuthorsThe manuscript presents a method for improving the digital receiving path of phased array antenna systems by incorporating a matched filter approach. While the topic of enhancing radar detection for low radar cross-section (RCS) objects is relevant, the paper lacks substantial innovation, rigor, and clarity, making it unsuitable for publication.
First and foremost, the suggested approach lacks sufficient originality. The application of matched filters in radar signal processing is a well-recognized method, and the paper lacks any notable progress or novel contributions in this domain. The proposed enhancements, such as implementing adaptive bias voltage modification for preamplifiers, are small and do not establish a significant advancement in radar technology. The present manuscript fails to provide innovative insights or answers to existing technological problems, which is a fundamental requirement for research work.
Additionally, the methodology is inadequately explained. Key technical details are missing, particularly regarding implementing the matched filter and the adaptive feedback system. The paper provides only a superficial overview of the system, with no clear description of how the adaptive "pseudo-expansion" of the linear gain range is achieved. Without a thorough and detailed explanation of the methodology, it is difficult to assess the practicality and validity of the proposed improvements.
Furthermore, the manuscript lacks engagement with the existing literature. The paper does not provide a comprehensive review of current techniques for detecting low-RCS objects or explain how the proposed approach compares with or improves upon these methods. This lack of context and positioning makes it difficult to understand the relevance or importance of the work.
Furthermore, the results section is deficient in both depth and rigor. Although the paper asserts that simulations have been carried out to confirm the soundness of the approach, it lacks any quantitative analysis or performance indicators. Insufficient inclusion of comprehensive simulation findings, comparison with alternative approaches, and a dearth of empirical testing greatly undermine the substance of the work. The data reported are mostly of a qualitative nature, providing limited empirical proof of the efficacy of the suggested methodology.
Author Response
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Comments 1: First and foremost, the suggested approach lacks sufficient originality. The application of matched filters in radar signal processing is a well-recognized method, and the paper lacks any notable progress or novel contributions in this domain. The proposed enhancements, such as implementing adaptive bias voltage modification for preamplifiers, are small and do not establish a significant advancement in radar technology. The present manuscript fails to provide innovative insights or answers to existing technological problems, which is a fundamental requirement for research work. Additionally, the methodology is inadequately explained. Key technical details are missing, particularly regarding implementing the matched filter and the adaptive feedback system. The paper provides only a superficial overview of the system, with no clear description of how the adaptive "pseudo-expansion" of the linear gain range is achieved. Without a thorough and detailed explanation of the methodology, it is difficult to assess the practicality and validity of the proposed improvements. |
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Response 1: Thank you for pointing this out. We agree with this comment. In contemporary radar technology, the observation and detection of objects with low radar cross-sections remains a significant challenge. A multi-functional radar model employing a digital phased array antenna system offers notable advantages over traditional radar in addressing this issue. Nonetheless, to fully capitalize on these benefits, improving the structure of the receiving path in digital transceiver modules is crucial. A method for improving the digital receiving path model by implementing a matched filter approach is introduced. Given that the return signals from objects are often lower than the internal noise, the analog part of the digital transceiver modules must ensure that its dynamic range aligns with the level of this noise and the weak signal. The output signal level of the analog part must correspond to the allowable input range of the analog-to-digital converter. Improvements in the receiving path to achieve a fully matched model can reduce errors in the phase parameters and amplitudes of the useful signal at the output. The simulation results presented in this paper demonstrate a reduction in amplitude error by approximately 1 dB and a phase error exceeding 1.5 degrees for the desired signal at the output of each receiving path. Consequently, these improvements are expected to enhance the overall quality and efficiency of the spatial and temporal accumulation processes in the digital phased array antenna system. Furthermore, to maintain the matched filter model, we also propose incorporating an adaptive “pseudo-expansion” of the linear gain range. This involves adding a feedback stage with an automatic and adaptive bias voltage adjustment for the intermediate-frequency preamplifier in the analog part of the receiving path. Simulations to qualitatively verify the validity of this proposal are conducted using data from practical operational radar system models. |
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Comments 2: Furthermore, the manuscript lacks engagement with the existing literature. The paper does not provide a comprehensive review of current techniques for detecting low-RCS objects or explain how the proposed approach compares with or improves upon these methods. This lack of context and positioning makes it difficult to understand the relevance or importance of the work. Response 2: It should be acknowledged that a substantial body of research has been published on this issue [12–20]. In the majority of these studies, researchers have identified the necessity to expand the dynamic range (linear gain range) of the receiving paths and have provided detailed technical solutions to address this need [12–14]. In addition, some research results have proposed solutions that combine different methods to solve the challenge of detecting low-RCS objects, for example, expanding the dynamic range based only on increasing the dynamic range of a certain element (e.g., of the analog-to-digital converter (ADC)) in the receiving path [15,17-19], or increasing a receiver’s overall linearity based on a digital nonlinear equalization (NLEQ) processor [16,18-20]. However, there is still an important issue: radio frequency (RF) receivers in general, and digital receivers and digital receiving paths in particular, often include components with different functions connected in series. According to classical signal filtering theory, these models are still often synthesized in the form of optimal filters to ensure the maximum signal-to-noise ratio at the output. References 12. Harker, B.J.; Dobrosavljevic, Z.; Craney, E.P.; Miles, S.; Belcher, R.A.; Chambers, J. Dynamic Range Enhancements in Radar Sensors PAPER A23. In Proceedings of the 4th EMRS DTC conference, Edinburgh, UK, 20 July 2007. 13. Harker, B.J.; Dobrosavljevic, Z.; Craney, E.P.; Tubb, C.M.; Harris, G.L. Dynamic range improvements and measurements in radar systems. IET J. 2007, 1, 398–406. https://doi.org/10.1049.iet-rsn:20060175. 14. Peccarelli, N.; James, B.; Fulton C.; Goodman N. Dynamic Range Considerations for Modern Digital Array Radars. 2020 IEEE International Radar Conference (RADAR), Washington, DC, USA, 2020, pp. 578-583, doi: 10.1109/RADAR42522.2020.9114607. 15. Denisov, A; Danilaev, D.P. Dynamic Range of a Digital Radio Receiver with a Photonic Analog-to-Digital Converter. J. Pap. Kazan Natl. Res. Tech. Univ. 2023, 26, 77–85. https://doi.org/10.22213/2413-1172-2023-4-77-85. 16. Goodman, J.; Miller, B.; Herman, M.; Vai; Monticciolo, P. Extending the dynamic range of RF receivers using nonlinear equalization. 2009 International Waveform Diversity and Design Conference, Kissimmee, FL, USA, 2009, pp. 224-228, doi: 10.1109/WDDC.2009.4800349. 17. Y. S. Poberezhskiy, "On Dynamic Range of Digital Receivers," 2007 IEEE Aerospace Conference, Big Sky, MT, USA, 2007, pp. 1-17, doi: 10.1109/AERO.2007.352968. 18. Raja Abdullah, R.S.A.; Alhaji Musa, S.; Abdul Rashid, N.E.; Sali, A.; Salah, A.A.; Ismail, A. Passive Forward-Scattering Radar Using Digital Video Broadcasting Satellite Signal for Drone Detection. Remote Sens. 2020, 12, 3075. https://doi.org/10.3390/rs12183075 19. Cheng, W.; Zhang, Q.; Lu, W.; Wang, H.; Liu, X. An Efficient Digital Channelized Receiver for Low SNR and Wideband Chirp Signals Detection. Appl. Sci. 2023, 13, 3080. https://doi.org/10.3390/app13053080. 20. N. Peccarelli, B. James, C. Fulton and N. Goodman, "Dynamic Range Considerations for Modern Digital Array Radars," 2020 IEEE International Radar Conference (RADAR), Washington, DC, USA, 2020, pp. 578-583, doi: 10.1109/RADAR42522.2020.9114607.
Comments 3: Furthermore, the results section is deficient in both depth and rigor. Although the paper asserts that simulations have been carried out to confirm the soundness of the approach, it lacks any quantitative analysis or performance indicators. Insufficient inclusion of comprehensive simulation findings, comparison with alternative approaches, and a dearth of empirical testing greatly undermine the substance of the work. The data reported are mostly of a qualitative nature, providing limited empirical proof of the efficacy of the suggested methodology. Response 3: Thank you for pointing this out. We agree with this comment. The simulation results presented in this paper demonstrate a reduction in amplitude error by approximately 1 dB and a phase error exceeding 1.5 degrees for the desired signal at the output of each receiving path. This study addresses the challenge of improving the structure of the receiving path in the DTMs of modern DPAA systems to improve the detection of objects with low RCSs, which are inherently difficult to detect. Through a comparative analysis supported by qualitative calculations, we propose a novel approach to modify the receiving path structure, transitioning from an optimal filtering model to a fully matched filtering model. To achieve this, the concept of dynamic range in the receiving path is adapted to scenarios where the signal levels from such objects are significantly lower than the internal noise levels. The results have created the premise for the proposal of “pseudo-expansion” of the linear gain range of the analog part of the receiving path. The improvement has allowed for a reduction in the amplitude errors and phase errors of the low signals reflected from objects with low RCSs, as demonstrated by the simulation results. This enhancement leads to improved signal accumulation, thereby increasing the signal-to-noise ratio () at the input of the digital detector of the radar system. Under optimal conditions, where intermodulation distortion noise between DTMs is minimized, the value has the potential to approach the value of . It is important to note that the detection of low RCS objects remains a significant challenge, necessitating the integration of various approaches for an effective solution. Among these, the improvement of the receiving path structure, as proposed in this paper, offers a promising approach that should be considered and applied in the research and design of modern multifunctional radar systems to ensure the capability to detect a wide range of object types.
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Author Response File: Author Response.docx
Reviewer 3 Report
Comments and Suggestions for AuthorsDear authors,
congratulations for your paper which is an interesting approach on the multi-functional radar with a digital phase array antenna system improvement.
I have some suggestions in order for you to improve your paper :
-please rephrase the title
-add some information about the structure of the paper in the abstract, present the sections and what do they contain
-edit the paper according to the template provided by the journal (see the text, figure names, tables)
-when you have an abbreviation please explain it when first used
-page 5 rephrase " the number of transceiver modules, Nmod , will approximately 741 elements."
-the subsections should be numbered
-some of the figures are surrounded by text, not in accordance to the template
-please place the formulas in text so that they are easier to be read
-correct the title of section 5
-in the conclusion section better highlight your contribution and talk about the result in general, not referencing so much the figures and tables
Comments on the Quality of English Language
There are some expressions that need to be rephrased and some sentences missing some words, please read again the paper and correct them.
Author Response
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Comments 1: please rephrase the title |
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Response 1: Thank you for pointing this out. We agree with this comment. Receiving Paths Improvement of Digital Phased Array Antennas Using Adaptive Dynamic Range. Enhance the reception paths of the digital phased array antenna by optimizing the adaptive dynamic range. |
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Comments 2: add some information about the structure of the paper in the abstract, present the sections and what do they contain Response 2: Thank you for pointing this out. We agree with this comment. Based on the analysis illustrated by qualitative estimates, the second section of this paper examines the characteristics of the receiving path in DTMs when the input signal consists of return signals from objects with low RCSs. The third section presents the content related to improving the structure of the receiving path to reduce the amplitude and phase errors of the return signals. This increases the efficiency of their processing and contributes to ensuring the ability to observe and detect objects with low RCSs. A simulation summary and analytical commentary are presented in the fourth section. The conclusions are presented in the final section. |
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Comments 3: edit the paper according to the template provided by the journal (see the text, figure names, tables) Response 3: Thank you for pointing this out. We agree with this comment. The formatting of the journal article has already been checked and corrected by the established rules. |
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Comments 4: when you have an abbreviation please explain it when first used Response 4: Thank you for pointing this out. We agree with this comment. We've already checked and corrected it
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Comments 5: page 5 rephrase " the number of transceiver modules, Nmod , will approximately 741 elements." Response 5: Thank you for pointing this out. We agree with this comment. => the number of transceiver modules will be approximately 741 elements.
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Comments 6: the subsections should be numbered Response 6: Thank you for pointing this out. We agree with this comment. We've already checked and corrected it
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Comments 7: some of the figures are surrounded by text, not in accordance to the template Response 7: Thank you for pointing this out. We agree with this comment. We've already checked and corrected it.
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Comments 8: please place the formulas in text so that they are easier to be read Response 8: Thank you for pointing this out. We agree with this comment. We've already checked and corrected it
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Comments 9: correct the title of section 5 Response 9: Thank you for pointing this out. We agree with this comment. We've already checked and corrected it => Conclusions
Comments 10: in the conclusion section better highlight your contribution and talk about the result in general, not referencing so much the figures and tables Response 10: Thank you for pointing this out. We agree with this comment. This study addresses the challenge of improving the structure of the receiving path in the DTMs of modern DPAA systems to improve the detection of objects with low RCSs, which are inherently difficult to detect. Through a comparative analysis supported by qualitative calculations, we propose a novel approach to modify the receiving path structure, transitioning from an optimal filtering model to a fully matched filtering model. To achieve this, the concept of dynamic range in the receiving path is adapted to scenarios where the signal levels from such objects are significantly lower than the internal noise levels. The results have created the premise for the proposal of “pseudo-expansion” of the linear gain range of the analog part of the receiving path. The improvement has allowed for a reduction in the amplitude errors and phase errors of the low signals reflected from objects with low RCSs, as demonstrated by the simulation results. This enhancement leads to improved signal accumulation, thereby increasing the signal-to-noise ratio () at the input of the digital detector of the radar system. Under optimal conditions, where intermodulation distortion noise between DTMs is minimized, the value has the potential to approach the value of . It is important to note that the detection of low RCS objects remains a significant challenge, necessitating the integration of various approaches for an effective solution. Among these, the improvement of the receiving path structure, as proposed in this paper, offers a promising approach that should be considered and applied in the research and design of modern multifunctional radar systems to ensure the capability to detect a wide range of object types.
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Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsIt may be accepted for publication.
