Commit dda4cf0c119a81ef5ae8f1c6c4b615ae72a9f67c

Authored by Arthur HUGEAT
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Lettre aux reviewers.

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ifcs2018_journal_reponse2.tex
% MANUSCRIPT NO. TUFFC-09469-2019.R1 1 1 % MANUSCRIPT NO. TUFFC-09469-2019.R1
% MANUSCRIPT TYPE: Papers 2 2 % MANUSCRIPT TYPE: Papers
% TITLE: Filter optimization for real time digital processing of radiofrequency signals: application to oscillator metrology 3 3 % TITLE: Filter optimization for real time digital processing of radiofrequency signals: application to oscillator metrology
% AUTHOR(S): HUGEAT, Arthur; BERNARD, Julien; Goavec-Mérou, Gwenhaël; Bourgeois, Pierre-Yves; Friedt, Jean-Michel 4 4 % AUTHOR(S): HUGEAT, Arthur; BERNARD, Julien; Goavec-Mérou, Gwenhaël; Bourgeois, Pierre-Yves; Friedt, Jean-Michel
5
6 \documentclass[a4paper]{article}
7 \usepackage[english]{babel}
8 \usepackage{fullpage,graphicx,amsmath, subcaption}
9 \begin{document}
10 \begin{center}
11 {\bf\Large
12 Rebuttal letter to the review #2 of the manuscript entitled
13
14 ``Filter optimization for real time digital processing of radiofrequency
15 signals: application to oscillator metrology''
16 }
17
18 by A. Hugeat \& al.
19 \end{center}
20
% 5 21 %
% REVIEWERS' COMMENTS: 6 22 % REVIEWERS' COMMENTS:
% Reviewer: 1 7 23 % Reviewer: 1
% 8 24 %
% Comments to the Author 9 25 % Comments to the Author
% The Authors have implemented all Reviewers’ remarks except the one related to the criterion that, in my opinion, is the most important one. By considering “the minimal rejection within the stopband, to which the sum of the absolute values within the passband is subtracted to avoid filters with excessive ripples, normalized to the bin width to remain consistent with the passband criterion (dBc/Hz units in all cases)” (please, find a way to state criterions more clearly), the Authors get filters with very different behaviors in pass band and, consequently, their comparison loses its meaning. 10 26 % The Authors have implemented all Reviewers’ remarks except the one related to the criterion that, in my opinion, is the most important one. By considering ``the minimal rejection within the stopband, to which the sum of the absolute values within the passband is subtracted to avoid filters with excessive ripples, normalized to the bin width to remain consistent with the passband criterion (dBc/Hz units in all cases)'' (please, find a way to state criterions more clearly), the Authors get filters with very different behaviors in pass band and, consequently, their comparison loses its meaning.
% In practice, the Authors use a good method based on a bad criterion, and this point weakens a lot the results they present. 11 27 % In practice, the Authors use a good method based on a bad criterion, and this point weakens a lot the results they present.
% In phase noise metrology, the target is an uncertainty of 1 dB, even less. In this regard, I would personally use a maximum ripple in pass band of 1 dB (or less), while, in some cases, the filters presented in the Manuscript exceed 10 dB of ripple, which is definitely too much. 12 28 % In phase noise metrology, the target is an uncertainty of 1 dB, even less. In this regard, I would personally use a maximum ripple in pass band of 1 dB (or less), while, in some cases, the filters presented in the Manuscript exceed 10 dB of ripple, which is definitely too much.
% The Authors seem to be reactive in redoing the measures and it does not seem a big problem for them to re-run the analysis with a better criterion. The article would gain a lot, because, in addition to the methodology, the reader could understand if it is actually better to put a cascade of small filters rather than a single large filter that is an interesting point. 13 29 % The Authors seem to be reactive in redoing the measures and it does not seem a big problem for them to re-run the analysis with a better criterion. The article would gain a lot, because, in addition to the methodology, the reader could understand if it is actually better to put a cascade of small filters rather than a single large filter that is an interesting point.
% To help the Authors in finding a better criterion (“…finding a better criterion to avoid the ripples in the passband is challenging...”), in addition to the minimum rejection in stop band, I suggest to specify also the maximum ripple in pass band as it is done, for example, in fig. 4.10, pg. 146 of Crochierie R. E. and Rabiner L. R. (1983) “Multirate Digital Signal Processing”, Prentice-Hall (see attach). This suggestion, in practice, specify the maximum allowed deviation from the transfer function modulus of an ideal filter: 1 in pass band and 0 in stop band. As a result, it should solve one of the Authors’ concerns: “Selecting a strong constraint such as the sum of absolute values in the passband is too selective because it considers all frequency bins in the passband while the stopband criterion is limited to a single bin at which rejection is poorest…” since both pass and stop bands are considered in the same way. 14 30 % To help the Authors in finding a better criterion (``…finding a better criterion to avoid the ripples in the passband is challenging...''), in addition to the minimum rejection in stop band, I suggest to specify also the maximum ripple in pass band as it is done, for example, in fig. 4.10, pg. 146 of Crochierie R. E. and Rabiner L. R. (1983) ``Multirate Digital Signal Processing'', Prentice-Hall (see attach). This suggestion, in practice, specify the maximum allowed deviation from the transfer function modulus of an ideal filter: 1 in pass band and 0 in stop band. As a result, it should solve one of the Authors’ concerns: ``Selecting a strong constraint such as the sum of absolute values in the passband is too selective because it considers all frequency bins in the passband while the stopband criterion is limited to a single bin at which rejection is poorest…'' since both pass and stop bands are considered in the same way.
% I understand that the Manuscript is devoted to present a methodology (“In this article we focus on the methodology, so even if our criterion could be improved, our methodology still remains and works independently of rejection criterion.”). Please, remember that a methodology is a solution to a class of problems and the example chosen to present the methodology plays a key role in showing to the reader if the method is valid or not. Here the example problem is represented by the synthesis of a decimation filter to be used in phase noise metrology. Many of the filters presented by the Authors in figures 9 and 10 as the output of this methodology are not suitable to be used in this context, since, for example, some of them have an attenuation as high as 50 dB in DC (!) that poses severe problems in interpreting the phase noise power spectral densities. What is the cause of this fail? The methodology or the criterion? 15 31 %
% In my opinion, it is mandatory to correct the criterion and to re-run the analysis for checking if the methodology works properly or not. 16 32 % I understand that the Manuscript is devoted to present a methodology (``In this article we focus on the methodology, so even if our criterion could be improved, our methodology still remains and works independently of rejection criterion.''). Please, remember that a methodology is a solution to a class of problems and the example chosen to present the methodology plays a key role in showing to the reader if the method is valid or not. Here the example problem is represented by the synthesis of a decimation filter to be used in phase noise metrology. Many of the filters presented by the Authors in figures 9 and 10 as the output of this methodology are not suitable to be used in this context, since, for example, some of them have an attenuation as high as 50 dB in DC (!) that poses severe problems in interpreting the phase noise power spectral densities. What is the cause of this fail? The methodology or the criterion?
% In the end, I suggest to publish the Manuscript After Minor Revisions. 17 33
34 {\bf
35 In my opinion, it is mandatory to correct the criterion and to re-run the analysis for checking if the methodology works properly or not.
36 In the end, I suggest to publish the Manuscript After Minor Revisions.
37 }
38
39 We have change our criterion to be more selective in passband. Now, when the filter response
40 exceed 1~dB in the passband, we discard the filter. We have re-run all experimentation
41 and we have updated the dataset and our conclusion. The methodology provide the
42 same results but since we have less filters we found the optimal solution earlier.
43 Our argumentation about the needed time to compute the optimal solution is not so
44 valid anymore since we need less time but we can also see that for biggest cases
45 we need more time.
46
47 \end{document}
18 48