Research on a Broadband Digital Receiver Based on Envelope Differentiation

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

1. Section 1 (line 34-41): The author discuss the complexity of the signal environment and the demands placed on receivers, but it is lacking details about the specific challenges posed by dense and complex signal environments would enhance the context. Please cite more research to address that.
2. Line 155-169: Please add more detailed explanations of the steps involved in applying the method, including the differentiation process and peak detection. For the two equations, can the author add more discussions, such as why it is used, limitation of the applications, etc.
3. Line 234-241: Please explain how the SNR range could affect the result comparison.
4. Can the author discuss what is the limitation of the proposed method?

Author Response

Comments1. Section 1 (line 34-41): The author discuss the complexity of the signal environment and the demands placed on receivers, but it is lacking details about the specific challenges posed by dense and complex signal environments would enhance the context. Please cite more research to address that

Response1:

Thanks for the questions.We have added the following sentences and more research to enhance the context in line 35-41.

“the digital receiver needs to receive a variety of radar signals, with very complex wavelength durations that may have any in-pulse modulation[2], Moreover, the amplitude and dual-tone instantaneous dynamic range of different signals vary greatly[3-5]. Collectively, these requirements impose more stringent demands on the sensitivity, instantaneous dual-tone dynamic detection range, and TOA of the accuracy. Especially, signal TOAdetection assumes a critical role,within the wideband digital receiver framework, this paper proposes a method focused on improving the accuracy and reliability of TOA detection.”

Comments2.Line 155-169: Please add more detailed explanations of the steps involved in applying the method, including the differentiation process and peak detection, For the two equations. Can the author add more discussions, such as why it is used, limitation of the applications, etc.

Response2:

Thanks for the questions. We have added the following sentences to strengthen this part.

"The processing sequence of the digitized intermediatefrequency data from the ADC is as follows: First, the raw intermediate-frequency data is decomposed into multiple narrowband channels through digital channelization processing using an array of adjacent digital filters. For each channel, the instantaneous amplitude is calculated from the filtered IF signals. When the amplitude of a specific channel exceeds a predefined threshold—indicating signal presence—the corresponding channel data undergoes matched filtering to generate the signal envelope. By applying the analytical expressions derived in Section 2.2 (Equations 6 and 13), the (TOA) is estimated with sub-sample precision. Finally, the TOA, amplitude, and other critical parameters are encoded into a PDW for subsequent signal analysis and classification."

Comments3.Line 234-241: Please explain how the SNR range could affect the result comparison

Response3:

Thank you for your insightful feedback. To address this, we have expanded the explanation in Section 3.2, as detailed in the attached revised manuscript.This discrepancy arises because traditional threshold-based TOA estimation algorithms inherently depend on signal pulse amplitude measurements for threshold calculation. Under low SNR conditions, these amplitude measurements exhibit significant inaccuracies due to noise corruption, propagating errors into the threshold decision process. In contrast, the proposed envelope differentiation method circumvents this dependency by directly extracting temporal features from the received signal envelope. This non-threshold-based approach maintains robustness against noise perturbations, thereby enabling more precise TOA estimation in challenging low SNR scenarios. At higher SNRs (> -2 dB), both methods achieve comparable accuracy with RMSE below 1×10⁻⁷, highlighting the proposed method’s particular advantage in challenging electromagnetic environments. "

Comments4. Can the author discuss what is the limitation of the proposed method?

 Response4:

Thanks for the questions, we have included a discussion of the limitations of this method in the manuscript's discussion section.

 

" However, this method demonstrates poor adaptability to high-frequency noise and complex signals due to the inherent sensitivity of differentiation processing to high-frequency noise, particularly under low SNR conditions. Additionally, in multipath environments, signal envelope distortion occurs, complicating the ability of differentiation processing to accurately track the true signal front, both of which contribute to inaccurate TOA detection. "

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Document attached

Comments for author File: Comments.pdf

Comments on the Quality of English Language

There are typographical errors in some words. While the English is understandable, all typos need to be corrected throughout the document.

Author Response

Comments1: The introduction cites papers that are somewhat outdated. It does not clearly highlight which specific parameter is being targeted to improve performance.

Response1:

Thank you for your question. We have removed some outdated literature and added a description focusing on improving the accuracy of signal TOA detection in in Section 1. Especially, signal TOA detection assumes a critical role, within the wideband digital receiver framework, this paper proposes a method focused on improving the accuracy and reliability of TOA detection."

 

Comments2: In the methodology section, only two studies are mentioned, and there is no reference to envelope differentiation. Is this the first time this methodology is being presented in a paper?

Response2:

Thank you for your question. Envelope differentiation has been previously applied in other fields. We adapted this method for radar signal processing and incorporated relevant references in section(2.2). While envelope differentiation has been previously utilized in low-power wireless devices [23] and communication signal demodulation [24], this paper presents its application to radar TOA detection. "

Comments3: In the design section (2.3), the potential challenges of implementing this solution are not discussed, nor are possible ways to overcome these difficulties outlined.

Response3:

Thank you for your question, we have added the following sentences to explain that in the design section (2.3).

However, this method demonstrates poor adaptability to high-frequency noise and complex signals due to the inherent sensitivity of differentiation processing to high-frequency noise, particularly under low SNRconditions. Additionally, in multipath environments, signal envelope distortion occurs, complicating the ability of differentiation processing to accurately track the true signal front, both of which contribute to inaccurate TOA detection."

 

Comments4: In Section 3.1, an RMSE formula is introduced, followed by a citation of article [24], which is not included in the bibliography. Consistency is important in this regard.

Response4:

Thank you for your question. We have updated the cited literature to reference 16 and relocated the citation to ensure greater accuracy in the article.

 

Comments5: Section 3.3, which presents the experimental results, is difficult to understand. The figure captions are all identical and grammatically incorrect, and the descriptions do not help clarify the contributions this paper is making.

Response5:

Thank you for your question. We appreciate the reviewer's valuable feedback. We have thoroughly revised Section 3.3 to enhance clarity and methodological significance. The revised content appears and Figs.5-9 in the updated manuscript. All figure captions have been proofread.

" Digital channelization of three distinct signal types via multiphase filtering reveals critical spectral characteristics, as presented in Figures 4(a), 6(a), and 8(a). These results consistently demonstrate prominent spectral peaks in Channel 17, confirming successful isolation of intermediate-frequency components within this specific channel. Subsequent analysis of real-component channelized intermediate-frequency signals and their envelope-differentiated derivatives (Figures 4(b), 6(b), and 8(b)) reveals transient peak signatures at signal onset across all signal categories. Experimental validation shows that temporal localization of these peaks, combined with channel index parameters, enables precise TOA estimation with nanosecond-level resolution.

Comments6: The quality of the figures is poor; the numbers, axes, and legends :are hard to read.

Response6:

Thanks for the comment. Based on the background color of the figures, we have revised the font color of the texts in figures 4 to 9. Meanwhile, the figure format has been changed from JPEG to PNG to improve its clarity. The resolution of figures have increased correspondingly.

 

Comments7. The discussion section lacks a comparison with other existing methods in the literature. This makes it challenging to understand where your work stands in relation to other approaches.

Response7:

Thanks for the questions.A comparison of different methods is now provided in the revised manuscript

 

“Correlation convolution methods exhibit inferior accuracy and reliability under low SNR conditions, while time-frequency methods and deep learning-based approaches impose prohibitive computational complexity and poor real-time performance, rendering them impractical for engineering applications.”

 

Comments8. This paper only presents simulations. What challenges might arise when this algorithm is implemented in real-world situations?

Response8:

Thanks for the questions, we have included a discussion of the limitations of this method in the manuscript's discussion section.

 

“However, this method demonstrates poor adaptability to high-frequency noise and complex signals due to the inherent sensitivity of differentiation processing to high-frequency noise, particularly under low SNR conditions. Additionally, in multipath environments, signal envelope distortion occurs, complicating the ability of differentiation processing to accurately track the true signal front, both of which contribute to inaccurate TOA detection.”

 

Comments9:The conclusion does not emphasize the key findings of the paper.

Response9:

Thank you for pointing out this issue. We have revised the conclusion section to better emphasize the key findings of the paper according to the following enhancements.

 

“In this paper, a digital channelized receiver design method based on first-order envelope differentiation of the signal is proposed. The approach is validated through time-aligned extraction of signals from different regimes by estimating the peak occurrence location. Experimental results demonstrate that the proposed method significantly enhances both reliability and accuracy compared to conventional techniques. A key contribution lies in the ability to accurately extract TOA through envelope differentiation while maintaining noise-robustness for signals with large transient dynamics. This innovation resolves the long-standing issue of amplitude-dependent TOA estimation errors in wideband receivers, The robustness is verified across varying SNRs and amplitude conditions. Additionally, the proposed framework can be readily integrated into existing signal arrival time extraction methodologies, expanding its applicability to broader engineering scenarios. The novel combination of envelope differentiation and time-aligned processing introduces a new method for TOA estimation in digital receivers, with potential applications in cognitive radar systems and wireless localization networks.”

 

Comments10. The bibliography needs to be checked. Reference [10] does not correspond to what is written. The article is not authored by the mentioned authors. Please verify the DOI.

Response10:

Thank you for your question. We have removed this reference to ensure more accurate citations and article content.

 

Comments11. There are typographical errors in some words. While the English is understandable, all typos need to be corrected throughout the document.

Response11:

Thank you for your feedback. We have revised the manuscript to correct erroneous expressions and spelling errors, ensuring greater accuracy and readability.

 

 

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The suggested corrections have been implemented.
The English phrasing needs improvement.
The text should be reviewed by a native English speaker or a professional proofreader.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

To be improved

Author Response

Comment 1: Line 4 and 6: Ming Li2, *, Qinghua Liu1 (Add spaces after commas)
chenbao@mails.guet.edu.cn and qhliu@guet.edu.cn. (Missing space after “cn”)

Response1:
Thanks for the questions. We have added spaces context in line 4 and 6.
“BaoChen1,2, Ming Li2,*, Qinghua Liu1
 
1    School of Information and Communication,Guilin University of Electronic Technology, Guilin 541004, China; chenbao@mails.guet.edu.cn and qhliu@guet.edu.cn .
2    Intelligent Electromagnetic Spectrum Sensing and Control Technology Engineering Research Center, Guilin 541001, China; mingli@mail.xidian.edu.cn .
*    Correspondence: mingli@mail.xidian.edu.cn ;  
“

Comment 2: Line 37: … and the dual-tone instantaneous dynamic range of different signals varies greatly. (Missing article "the" and verb agreement)
Response2:
Thanks for the questions. We have revised the sentence in line 37-38.
“… and the dual-tone instantaneous dynamic range of different signals vary greatly [3-5].”

Comment 3: Line 35: the digital receiver must handle various radar signals with complex wavelength durations and possible in-pulse modulation. (Incorrect Verb Form / Agreement)
Response3:
Thanks for the comment. We have modified this sentence in line 35-36.
“the digital receiver needs to receive a variety of radar signals with complex wavelength durations and possible in-pulse modulation [2] ”

 

Comment 4: Line 41-42: a critical role. Within the wideband digital receiver framework, this paper proposes a method focused on improving TOA detection accuracy and reliability. Meanwhile, the instantaneous bandwidth of narrowband radar signals is generally… (Fix punctuation and sentence division)
Response4:
Thanks for the comment. We have changed the punctuation and sentence division in line 40-42.
“Especially, signal TOA detection assumes a critical role. Within the wideband digital receiver framework, this paper proposes a method focused on improving the accuracy and reliability of TOA detection.”

Comment 5: Line 92: but they are also not easy to implement in engineering. (Missing space in "implementin")
Response5:
Thanks for the questions. We have revised the sentence in line 92.
“ but they are also not easy to implement in engineering.”

Comment 6: Line 98: The experimental results verify the effectiveness and reliability of the signal arrival time extraction method. (Use "experimental" instead of "experiment results")
Response6:
Thanks for your question. We have revised the sentence in line 24.
“The experimental results verify the effectiveness and reliability of the signal arrival time extraction method. “