Commit 6e9e0d2f authored by Maciej Lipinski's avatar Maciej Lipinski

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parent aca6f57c
......@@ -324,15 +324,15 @@ USA (NIST) and Italy (INRIM) have WR installations, see Table~\ref{tab:timelabs}
\textbf{Time} & \textbf{Link} & \textbf{Link } & \textbf{Time } & \textbf{Time} & \textbf{Ref} \\
\textbf{Lab} & \textbf{Length } & \textbf{Type } & \textbf{Error} & \textbf{Stability} & \textbf{} \\ \hline
VTT & 950~km & unidir. in DWDM & $\pm$2ns & 20ps@1000s & \cite{biblio:MIKES+VSL} \\ \cline{2-6}
MIKES & 50~km & bidir. on adjacent ITU DWDM channels & $<$1ns & ~2e-12@1s (*) & \cite{biblio:MIKES-50km} \\ \hline
MIKES & 50~km & bidir. on adjacent ITU DWDM channels & $<$1ns & ~2ps@1s (*) & \cite{biblio:MIKES-50km} \\ \hline
VSL & 2x137~km & bidir. on CWDM (1470\&1490nm)(\#) & $<$8ns & 10ps@1000s & \cite{biblio:MIKES+VSL} \\ \hline
& 25~km & unidir. at 1541nm & 150ps & 1-2ps@1000s & \cite{biblio:SYRTE-LNE-25km} \\ \cline{2-6}
LNE- & 25~km & bidir. at 1310\&1490nm & 150ps & 1-2ps@1000s & \cite{biblio:SYRTE-LNE-25km} \\ \cline{2-6}
SYRTE & 125~km & unidir. in the C-band or close OSC channel & 2.5ns & 1ps@1s (**) & \cite{biblio:SYRTE-LNE-500km} \\ \cline{2-6}
& 4x125~km & unidir. in the C-band or close OSC channel & 2.5ns & 5.5ps@1s (**) & \cite{biblio:SYRTE-LNE-500km} \\ \hline
NIST & $<$10~km & bidir. standard WR (1310\&1490nm \cite{biblio:wr-sfps})& below 200ps & 20ps@1s & \cite{biblio:WR-NIST} \\ \hline
NPL & 2x80~km & unidir. in DWDM & $<$1ns & & \cite{biblio:NPL}\\ \cline{2-5}
& $<$10~km & bidir. standard WR & $<$1ns & & \\ \hline
NPL & 2x80~km & unidir. in DWDM & $<$1ns & 1-2ps@1000s & \cite{biblio:NPL}\\ \cline{2-5}
& $<$10~km & bidir. standard WR & $<$1ns & 1.5ps@1000s & \\ \hline
& 50~km & bidir. in WDM & 800ps $\pm$56ps& & \cite{biblio:WR-INRIM} \\ \cline{2-6}
INRIM & 70~km & bidir. in WDM & 610ps $\pm$47ps& & \cite{biblio:WR-INRIM} \\ \cline{2-6}
& 400~km & unidir. in DWDM & & & \cite{biblio:WR-INRIM-400km} \\ \hline
......@@ -752,7 +752,7 @@ is controlled by a "Bunch Clock" system\footnote{
A "Bunch Clock" system generates a clock signal that is synchronous with particle bunches
circulating in a synchrotron or an accelerator.}
that delivers to accelerator subsystems a
$\approx$352 MHz RF signal and triggers initiating sequential actions synchronous
$\approx$352~MHz RF signal and triggers initiating sequential actions synchronous
to the RF signal, such as
"gun trigger", "injection trigger" or "extraction trigger"\footnote{
"Gun trigger" initiates generation of an electron bunch at the LINAC input,
......@@ -768,7 +768,7 @@ process. Apart from the 352~MHz signal, other frequencies are distributed, such
The current ESRF "Bunch Clock" system is being refurbished to use WR \cite{biblio:ESRF-WR}.
The solution has passed a 6-months validation test in 2015. In 2016, a prototype system
successfully injected
bunches in the storage ring providing $<$10ps jitter. A system consisting
bunches in the storage ring providing $<$10~ps jitter. A system consisting
of a WR switch and eight WR nodes is expected to be operational in July 2018. It
will be expanded to 41 WR nodes and 4-5 WR switches by 2020.
The ESRF "Bunch Clock" system not only distributes a number of RF frequencies,
......@@ -777,7 +777,7 @@ frequencies.
The radio-frequency transfer in CERN's Super Proton Synchrotron (SPS)
accelerator is also being upgraded to use WR. The SPS requires distribution
of a 200~MHz RF signal with 0.25ps RMS jitter (100Hz to 100kHz) and an accuracy of $\pm$10ps.
of a 200~MHz RF signal with 0.25~ps RMS jitter (100~Hz to 100~kHz) and an accuracy of $\pm$10~ps.
These requirements necessitate enhancements of WR.
% \section{WR Applications outside CERN}
......@@ -1203,7 +1203,7 @@ modifications to the WR-PTP Protocol, see
The improved WR Switches are now commercially available \cite{biblio:WR-LJD-switch}.
A high performance low-jitter WR node is developed for the SPS's RF transmission
achieving jitter of sub-100fs RMS from 100Hz to 20MHz \cite{biblio:SPS-WR-LLRF}.
achieving jitter of sub-100fs RMS from 100~Hz to 20~MHz \cite{biblio:SPS-WR-LLRF}.
A WR node \cite{biblio:SPEV7} to achieve stability of 1e-13 over 100 s is designed
within the WRITE project \cite{biblio:WRITE-2}.
\subsection{Temperature Compensation}
......@@ -1240,9 +1240,9 @@ On the 137~km bidirectional link in the Netherlands \cite{biblio:MIKES+VSL},
dedicated optical amplifiers that work with bidirectional fibers are used in
an attempt to overcome these limitation. The tests so far have shown $<$8~ns accuracy
while a new "in-site" calibration under development at VLS is expected to calibrate
out this asymmetry (over a 2x 137~km link) to a few hundred picoseconds or less \cite{biblio:VLS-WR-insite-calib}.
out this asymmetry (over a 2x137~km link) to a few hundred picoseconds \cite{biblio:VLS-WR-insite-calib}.
On the 950~km unidirectional link in Finland \cite{biblio:MIKES+VSL}, GPS precise point positioning
(PPP) was used to calibrate asymmetry and achieve $\pm$2~ns accuracy. This
was used to calibrate asymmetry and achieve $\pm$2~ns accuracy. This
method requires re-calibration after any disruption of the network. Laboratory
tests of a 500~km WR connection using five cascaded WR devicies and four 125~km unidirectional
links showed a 2.5~ns peak-to-peak time error \cite{biblio:SYRTE-LNE-500km}.
......
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