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Authored by Arthur HUGEAT
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Merge branch 'master' of https://lxsd.femto-st.fr/gitlab/jfriedt/ifcs2018-article

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... ... @@ -185,4 +185,12 @@
185 185 year={2002},
186 186 publisher={Elsevier}
187 187 }
  188 +
  189 +@article{andrich2018high,
  190 + title={High-Precision Measurement of Sine and Pulse Reference Signals Using Software-Defined Radio},
  191 + author={Andrich, Carsten and Ihlow, Alexander and Bauer, Julia and Beuster, Niklas and Del Galdo, Giovanni},
  192 + journal={IEEE Transactions on Instrumentation and Measurement},
  193 + year={2018},
  194 + publisher={IEEE}
  195 +}
ifcs2018_proceeding.tex
  1 +% JMF : revoir l'abstract : on y avait mis le Zynq7010 de la redpitaya en montrant
  2 +% comment optimiser les perfs a surface finie. Ici aussi on tombait dans le cas ou`
  3 +% la solution a 1 seul FIR n'etait simplement pas synthetisable => fusionner les deux
  4 +% contributions pour le papier TUFFC
  5 +
1 6 \documentclass[a4paper,conference]{IEEEtran/IEEEtran}
2 7 \usepackage{graphicx,color,hyperref}
3 8 \usepackage{amsfonts}
... ... @@ -67,7 +72,7 @@
67 72 the non-linear behavior of the downconverter introduces noise or spurious signal aliasing as
68 73 well as the generation of the frequency sum signal in addition to the frequency difference.
69 74 These unwanted spectral characteristics must be rejected before decimating the data stream
70   -for the phase noise spectral characterization. The characteristics introduced between the
  75 +for the phase noise spectral characterization \cite{andrich2018high}. The characteristics introduced between the
71 76 downconverter
72 77 and the decimation processing blocks are core characteristics of an oscillator characterization
73 78 system, and must reject out-of-band signals below the targeted phase noise -- typically in the
... ... @@ -92,7 +97,7 @@
92 97 defining the coefficients and the sample size. For this reason, and because we consider pipeline
93 98 processing (as opposed to First-In, First-Out FIFO memory batch processing) of radiofrequency
94 99 signals, High Level Synthesis (HLS) languages \cite{kasbah2008multigrid} are not considered but
95   -the problem is tackled at the Very-high-speed-integrated-circuit Hardware Description Language (VHDL).
  100 +the problem is tackled at the Very-high-speed-integrated-circuit Hardware Description Language (VHDL) level.
96 101 Since latency is not an issue in a openloop phase noise characterization instrument, the large
97 102 numbre of taps in the FIR, as opposed to the shorter Infinite Impulse Response (IIR) filter,
98 103 is not considered as an issue as would be in a closed loop system.
... ... @@ -203,8 +208,8 @@
203 208 \end{cases}
204 209 \label{model-FIR}
205 210 \end{align}
206   -To explain the system \ref{model-FIR}, $\mathcal{R}_i$ represents the rejection of depending on $N_i$ and $C_i$, $\mathcal{A}$
207   -is a theoretical area occupation of the processing block on the FPGA, and $\Delta_i$ is the total rejection for the current stage $i$.
  211 +To explain the system \ref{model-FIR}, $\mathcal{R}_i$ represents the stopband rejection dependence with $N_i$ and $C_i$, $\mathcal{A}$
  212 +is a theoretical area occupation of the processing block on the FPGA as discussed earlier, and $\Delta_i$ is the total rejection for the current stage $i$.
208 213 Since the function $\mathcal{F}$ cannot be explictly expressed, we run simulations to determine the rejection depending
209 214 on $N_i$ and $C_i$. However, selecting the right filter requires a clear definition of the rejection criterion. Selecting an
210 215 incorrect criterion will lead the linear program solver to produce a solution which might not meet the user requirements.
211 216  
... ... @@ -223,13 +228,17 @@
223 228 \end{figure}
224 229  
225 230 The objective function maximizes the noise rejection ($\max(\Delta_{i_{\max}})$) while keeping resource occupation below
226   -a user-defined threshold. The MILP solver is allowed to choose the number of successive
  231 +a user-defined threshold, or aims at minimizing the area needed to reach a given rejection ($\min(S_q)$ in
  232 +the forthcoming discussion, Eqs. \ref{cstr_size} and \ref{cstr_rejection}).
  233 +The MILP solver is allowed to choose the number of successive
227 234 filters, within an upper bound. The last problem is to model the noise rejection. Since filter
228 235 noise rejection capability is not modeled with linear equations, a look-up-table is generated
229 236 for multiple filter configurations in which the $C_i$, $D_i$ and $N_i$ parameters are varied: for each
230   -one of these conditions, the low-pass filter rejection defined as the mean power between
231   -half the Nyquist frequency and the Nyquist frequency is stored as computed by the frequency response
232   -of the digital filter (Fig. \ref{noise-rejection}). An intuitive analysis of this chart hints at an optimum
  237 +one of these conditions, the low-pass filter rejection is stored as computed by the frequency response
  238 +of the digital filter (Fig. \ref{noise-rejection}). Various rejection criteria have been investigated,
  239 +including mean value of the stopband response, median value of the stopband response, or as finally
  240 +selected, maximum value in the stopband. An intuitive analysis of the chart of Fig. \ref{noise-rejection}
  241 +hints at an optimum
233 242 set of tap length and number of bit for representing the coefficients along the line of the pyramidal
234 243 shaped rejection capability function.
235 244  
... ... @@ -303,7 +312,7 @@
303 312  
304 313 The resource occupation when synthesizing such FIR on a Xilinx FPGA is summarized as Tab. \ref{t1}.
305 314 We have considered a set of resources representative of the hardware platform we work on,
306   -Avnet's Zedboard featuring a Xilinx XC7Z020-CLG484-1 Zynq System on Chip (SoC). The results on
  315 +Avnet's Zedboard featuring a Xilinx XC7Z020-CLG484-1 Zynq System on Chip (SoC). The results reported in
307 316 Tab. \ref{t1} emphasize that implementing the monolithic single FIR is impossible due to
308 317 the insufficient hardware resources (exhausted LUT resources), while the FIR cascading 5 or 10
309 318 filters fit in the available resources. However, in all cases the DSP resources are fully