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ifcs2018_journal.tex
... | ... | @@ -405,16 +405,18 @@ |
405 | 405 | $\pi_i^S \leq \pi_i^- + \pi_i^C - 1 - \sum_{k=1}^{i} \left(1 + \frac{r_j}{6}\right)$. |
406 | 406 | Finally, equation~\ref{eq:init} gives the number of bits of the global input. |
407 | 407 | |
408 | -This model is non-linear and even non-quadratic, as $F$ does not have a known | |
409 | -linear or quadratic expression. We introduce $p$ FIR configurations | |
410 | -$(C_{ij}, \pi_{ij}^C), 1 \leq j \leq p$ that are constants. | |
411 | -% r2.12 | |
408 | +{\color{red} | |
409 | +This model is non-linear since we multiply some variable with another variable | |
410 | +and it is even non-quadratic, as $F$ does not have a known | |
411 | +linear or quadratic expression. To linearize this problem, we introduce $p$ FIR configurations. | |
412 | 412 | This variable must be defined by the user, it represent the number of different |
413 | 413 | set of coefficients generated (for memory, we use \texttt{firls} and \texttt{fir1} |
414 | -functions from GNU Octave). | |
415 | -We define binary | |
414 | +functions from GNU Octave). So $C_{ij}$ and $\pi_{ij}^C$ become constant and | |
415 | +we defined $1 \leq j \leq p$ and the function $F$ can be estimate for each configurations | |
416 | +thanks our rejection criterion. We also defined binary | |
416 | 417 | variable $\delta_{ij}$ that has value 1 if stage~$i$ is in configuration~$j$ |
417 | 418 | and 0 otherwise. The new equations are as follows: |
419 | +} | |
418 | 420 | |
419 | 421 | \begin{align} |
420 | 422 | a_i & = \sum_{j=1}^p \delta_{ij} \times C_{ij} \times (\pi_{ij}^C + \pi_i^-), & \forall i \in [1, n] \label{eq:areadef2} \\ |
421 | 423 | |
... | ... | @@ -427,13 +429,46 @@ |
427 | 429 | respectively equations \ref{eq:areadef}, \ref{eq:rejectiondef} and \ref{eq:bits}. |
428 | 430 | Equation~\ref{eq:config} states that for each stage, a single configuration is chosen at most. |
429 | 431 | |
430 | -% r2.13 | |
431 | -This modified model is quadratic since we multiply two variables in the | |
432 | -equation~\ref{eq:areadef2} ($\delta_{ij}$ by $\pi_{ij}^-$) but it can be linearised if necessary. | |
433 | -The Gurobi | |
432 | +{\color{red} | |
433 | +However the problem still quadratic since in the constraint~\ref{eq:areadef2} we multiply | |
434 | +$\delta_{ij}$ and $\pi_i^-$. But like $\delta_{ij}$ is a binary variable we can | |
435 | +linearise this multiplication if we can bound $\pi_i^-$. As $\pi_i^-$ is the data size | |
436 | +we define $0 < \pi_i^- \leq 128$ which is the maximal data size that we can process. | |
437 | +} | |
438 | +Moreover the Gurobi | |
434 | 439 | (\url{www.gurobi.com}) optimization software is used to solve this quadratic |
435 | 440 | model, and since Gurobi is able to linearize, the model is left as is. This model |
436 | 441 | has $O(np)$ variables and $O(n)$ constraints. |
442 | + | |
443 | +% This model is non-linear and even non-quadratic, as $F$ does not have a known | |
444 | +% linear or quadratic expression. We introduce $p$ FIR configurations | |
445 | +% $(C_{ij}, \pi_{ij}^C), 1 \leq j \leq p$ that are constants. | |
446 | +% % r2.12 | |
447 | +% This variable must be defined by the user, it represent the number of different | |
448 | +% set of coefficients generated (for memory, we use \texttt{firls} and \texttt{fir1} | |
449 | +% functions from GNU Octave). | |
450 | +% We define binary | |
451 | +% variable $\delta_{ij}$ that has value 1 if stage~$i$ is in configuration~$j$ | |
452 | +% and 0 otherwise. The new equations are as follows: | |
453 | +% | |
454 | +% \begin{align} | |
455 | +% a_i & = \sum_{j=1}^p \delta_{ij} \times C_{ij} \times (\pi_{ij}^C + \pi_i^-), & \forall i \in [1, n] \label{eq:areadef2} \\ | |
456 | +% r_i & = \sum_{j=1}^p \delta_{ij} \times F(C_{ij}, \pi_{ij}^C), & \forall i \in [1, n] \label{eq:rejectiondef2} \\ | |
457 | +% \pi_i^+ & = \pi_i^- + \left(\sum_{j=1}^p \delta_{ij} \pi_{ij}^C\right) - \pi_i^S, & \forall i \in [1, n] \label{eq:bits2} \\ | |
458 | +% \sum_{j=1}^p \delta_{ij} & \leq 1, & \forall i \in [1, n] \label{eq:config} | |
459 | +% \end{align} | |
460 | +% | |
461 | +% Equations \ref{eq:areadef2}, \ref{eq:rejectiondef2} and \ref{eq:bits2} replace | |
462 | +% respectively equations \ref{eq:areadef}, \ref{eq:rejectiondef} and \ref{eq:bits}. | |
463 | +% Equation~\ref{eq:config} states that for each stage, a single configuration is chosen at most. | |
464 | +% | |
465 | +% % r2.13 | |
466 | +% This modified model is quadratic since we multiply two variables in the | |
467 | +% equation~\ref{eq:areadef2} ($\delta_{ij}$ by $\pi_{ij}^-$) but it can be linearised if necessary. | |
468 | +% The Gurobi | |
469 | +% (\url{www.gurobi.com}) optimization software is used to solve this quadratic | |
470 | +% model, and since Gurobi is able to linearize, the model is left as is. This model | |
471 | +% has $O(np)$ variables and $O(n)$ constraints. | |
437 | 472 | |
438 | 473 | Two problems will be addressed using the workflow described in the next section: on the one |
439 | 474 | hand maximizing the rejection capability of a set of cascaded filters occupying a fixed arbitrary |
ifcs2018_journal_reponse.tex
... | ... | @@ -74,7 +74,7 @@ |
74 | 74 | %REVIEWERS' COMMENTS: |
75 | 75 | |
76 | 76 | \documentclass[a4paper]{article} |
77 | -\usepackage{fullpage,graphicx} | |
77 | +\usepackage{fullpage,graphicx,amsmath} | |
78 | 78 | \begin{document} |
79 | 79 | {\bf Reviewer: 1} |
80 | 80 | |
... | ... | @@ -85,7 +85,7 @@ |
85 | 85 | On page 2, "...allowing to save processing resource..." could be improved. % r1.1 |
86 | 86 | } |
87 | 87 | |
88 | -The sentence was split and now reads ``number of coefficients irrelevant: processing | |
88 | +The sentence was split and now reads ``number of coefficients irrelevant: processing | |
89 | 89 | resources are hence saved by shrinking the filter length.'' |
90 | 90 | |
91 | 91 | {\bf |
... | ... | @@ -95,7 +95,7 @@ |
95 | 95 | Grammatical error: this sentence now reads ``or by sampling a wideband (125~MS/s) |
96 | 96 | Analog to Digital Converter (ADC) loaded by a 50~$\Omega$ resistor.'' |
97 | 97 | |
98 | -{\bf | |
98 | +{\bf | |
99 | 99 | On page 2, the whole paragraph "The first step of our approach is to model..." % r1.3 |
100 | 100 | could be improved. |
101 | 101 | } |
... | ... | @@ -103,7 +103,7 @@ |
103 | 103 | Indeed this paragraph has be written again and now reads as\\ |
104 | 104 | ``The first step of our approach is to model the DSP chain. Since we aim at only optimizing |
105 | 105 | the filtering part of the signal processing chain, we have not included the PRN generator or the |
106 | -ADC in the model: the input data size and rate are considered fixed and defined by the hardware. | |
106 | +ADC in the model: the input data size and rate are considered fixed and defined by the hardware. | |
107 | 107 | The filtering can be done in two ways, either by considering a single monolithic FIR filter |
108 | 108 | requiring many coefficients to reach the targeted noise rejection ratio, or by |
109 | 109 | cascading multiple FIR filters, each with fewer coefficients than found in the monolithic filter. |
... | ... | @@ -197,8 +197,8 @@ |
197 | 197 | bandwidth. |
198 | 198 | } |
199 | 199 | |
200 | -See above: the absolute value within the passband will reject filters with | |
201 | -excessive ripples, including excessive attenuation, within the passband. | |
200 | +See above: the absolute value within the passband will reject filters with | |
201 | +excessive ripples, including excessive attenuation, within the passband. | |
202 | 202 | |
203 | 203 | {\bf |
204 | 204 | In addition, I suggest to address the following points: % r2.4 |
205 | 205 | |
... | ... | @@ -211,12 +211,11 @@ |
211 | 211 | have more than 5~coefficients. Hence, while a FIR requires 128 inputs before providing |
212 | 212 | the first output, an IIR will start providing outputs only 5 time steps after the initial |
213 | 213 | input starts feeding the IIR. Hence, the issue we address here is lag and not impulse |
214 | -response. We aimed at making this sentence clearer by stating that ``Since latency is not an issue | |
214 | +response. We aimed at making this sentence clearer by stating that ``Since latency is not an issue | |
215 | 215 | in a openloop phase noise characterization instrument, the large |
216 | 216 | numbre of taps in the FIR, as opposed to the shorter Infinite Impulse Response (IIR) filter, |
217 | 217 | is not considered as an issue as would be in a closed loop system in which lag aims at being |
218 | -minimized to avoid oscillation conditions. | |
219 | -'' | |
218 | +minimized to avoid oscillation conditions.'' | |
220 | 219 | |
221 | 220 | {\bf |
222 | 221 | - Fig. 4: the Author should motivate in the text why it has been chosen % r2.5 |
... | ... | @@ -243,8 +242,8 @@ |
243 | 242 | coefficient resolution? |
244 | 243 | } |
245 | 244 | |
246 | -We have now stated in the beginning of the document that ``we have not included the PRN generator | |
247 | -or the ADC in the model: the input data size and rate are considered fixed and defined by the | |
245 | +We have now stated in the beginning of the document that ``we have not included the PRN generator | |
246 | +or the ADC in the model: the input data size and rate are considered fixed and defined by the | |
248 | 247 | hardware.'' so indeed the input datastream resolution is considered as a given. |
249 | 248 | |
250 | 249 | {\bf |
251 | 250 | |
252 | 251 | |
253 | 252 | |
254 | 253 | |
255 | 254 | |
... | ... | @@ -268,21 +267,67 @@ |
268 | 267 | - Page 4, line 10: how $p$ is chosen? Which is the criterion used to choose % r2.12 - fait |
269 | 268 | these particular configurations? Are they chosen automatically? |
270 | 269 | } |
270 | +See below: we have added a better description of $p$ during the transformation explanation. | |
271 | +``we introduce $p$ FIR configurations. | |
272 | +This variable must be defined by the user, it represent the number of different | |
273 | +set of coefficients generated (for memory, we use \texttt{firls} and \texttt{fir1} | |
274 | +functions from GNU Octave)'' | |
271 | 275 | |
272 | -JMF : repondre | |
273 | - | |
274 | 276 | {\bf |
275 | 277 | - Page 4, line 31: how does the delta function transform model from non-linear % r2.13 - fait |
276 | 278 | and non-quadratic to a quadratic?} |
277 | 279 | |
280 | +The first model is non-quadratic but when we introduce the $p$ configurations, | |
281 | +we can estimate the function $F$ by computing | |
282 | +the rejection for each configuration, so the model become quadratic because we have | |
283 | +some multiplication between variables. With the definition of $\delta_{ij}$ we can | |
284 | +replace the multiplication between variables by multiplication with binary variable and | |
285 | +this one can be linearise as follow:\\ | |
286 | +$y$ is a binary variable \\ | |
287 | +$x$ is a real variable bounded by $X^{max}$ \\ | |
288 | +\begin{equation*} | |
289 | + m = x \times y \implies | |
290 | + \left \{ | |
291 | + \begin{split} | |
292 | + m & \geq 0 \\ | |
293 | + m & \leq y \times X^{max} \\ | |
294 | + m & \leq x \\ | |
295 | + m & \geq x - (1 - y) \times X^{max} \\ | |
296 | + \end{split} | |
297 | + \right . | |
298 | +\end{equation*} | |
299 | +Gurobi does the linearization so we don't explain this step to keep the model more | |
300 | +simple. However, to improve the transformation explanation we have rewrote the | |
301 | +paragraph ``This model is non-linear and even non-quadratic...''. | |
302 | + | |
278 | 303 | JMF : il faudra mettre une phrase qui explique, ca en lisant cette reponse dans l'article |
279 | 304 | je ne comprends pas comment ca repond a la question |
280 | 305 | |
306 | +AH: Je mets l'idée en français, je vais essayer de traduire ça au mieux. | |
307 | + | |
308 | +Le problème n'est pas linéaire car nous multiplions des variables | |
309 | +entre elles. Pour y remédier, on considère que $\pi_{ij}^C$ et que $C_{ij}$ deviennent | |
310 | +des constantes. On introduit donc la variable binaire $\delta_{ij}$ qui nous indique | |
311 | +quel filtre est sélectionné étage par étage. Malgré cela, notre programme est encore | |
312 | +quadratique car pour la contrainte~\ref{eq:areadef2}, il reste une multiplication entre | |
313 | +$\delta_{ij}$ et $\pi_i^-$. Mais comme $\delta_{ij}$ est binaire, il est possible | |
314 | +de linéariser cette multiplication pour peu qu'on puisse borner $\pi_i^-$. Dans notre | |
315 | +cas définir la borne est facile car $\pi_i^-$ représente une taille de donnée, | |
316 | +nous définission donc $0 < \pi_i^- \leq 128$ car il s'agit de la plus grande valeur | |
317 | +qu'on puisse traiter. De plus nous utiliserons Gurobi qui se chargera de faire la | |
318 | +linéarisation pour nous. | |
319 | + | |
320 | + | |
281 | 321 | {\bf |
282 | 322 | - Captions of figure and tables are too minimal. % r2.14 |
323 | +} | |
324 | +We have change the captions of fig 10-16. | |
325 | + | |
326 | +{\bf | |
283 | 327 | - Figures can be grouped: fig. 10-12 can be grouped as three subplots (a, b, c) % r2.15 - fait |
284 | 328 | of a single figure. Same for fig. 13-16. |
285 | 329 | } |
330 | +We add two sub figure to group the fig.10-12 and fig. 13-16 | |
286 | 331 | |
287 | 332 | {\bf |
288 | 333 | - Please increase the number of averages for the spectrum. Currently the noise % r2.16 - fait |
... | ... | @@ -290,7 +335,7 @@ |
290 | 335 | differences among the curves. I suggest to reduce the noise below 1 dBpk-pk. |
291 | 336 | } |
292 | 337 | |
293 | -Indeed averaging had been omitted during post-processing and figure generation: we | |
338 | +Indeed averaging had been omitted during post-processing and figure generation: we | |
294 | 339 | are grateful to the reviewer for emphasizing this point which has now been corrected. All spectra |
295 | 340 | now exhibit sub-dBpk-pl line thickness. |
296 | 341 |