1. WR Activities in Tsinghua
Guanghua Gong, Hongming Li, Xingwei Liu, Jianming Li
Dept. of Engineering Physics,
Tsinghua University
Qiang Du
Lawrence Berkeley National Lab
8th WR workshop, CERN Gevena, 6-7 Oct, 2014

2. Outline Temperature effect of WR link WR deployment at YBJ@Tibet
WR development at THU
other WR applications in China
Introduction to Ultrasync
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3. Temp. effect measurement of FIX DELAY
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4. Temp. effect calculation of FIX DELAY
Only ( ∆ 𝒕𝒙𝒔 , ∆ 𝒓𝒙𝒔 ) changes with temp.
δ 𝑑𝑒𝑙𝑎𝑦 𝑚𝑚 = δ ∆ 𝑟𝑥𝑠 + δ ∆ 𝑡𝑥𝑠
𝑜𝑓𝑓𝑠𝑒𝑡 =δ 𝑑𝑒𝑙𝑎𝑦 𝑚𝑠 = δ ∆ 𝑟𝑥𝑠 − δ ∆ 𝑡𝑥𝑠
δ txs1 =−7.9𝑝𝑠/℃
δ rxs1 = 𝑝𝑠/℃
δ txs2 =−8.8𝑝𝑠/℃
δ rxs2 = 𝑝𝑠/℃

5. Temp. effect correction of FIX DELAY
Take the average value (δ txs =−8.5𝑝𝑠/℃, δ rxs =13.0𝑝𝑠/℃ ) for temperature correction.
Node1
Node2
Node3
reduced from 800ps to 150ps in 70 ℃ temperature range
components diversity exists,
node calibration needed for high precision application.
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6. Temp. effect of fiber length
The refractive index of optical fiber has temp & wavelength dependency,
asymmetry coefficient 𝛂 is not constant, it has temperature dependency.
Fiber length 1KM
Fiber length 10KM
−0.2𝑝𝑠/(℃*Km)
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7. Temp. effect of SFP laser spectrum
SFP Type
AXGE
”Fabry-Perot”
0.11𝑝𝑠/(℃*Km)
SFP Type
AXGE
”Distributed Feedback”
−0.51𝑝𝑠/(℃*Km)
0.4~ 0.5 nm/℃
-1.3~0.9 ps/(nm*km)
-0.65~0.45 ps/(℃*km)
-0.23~0.33 ps/(℃*km)
0.08~ 0.12 nm/℃
12.9~14.4 ps/(nm*km)
1.03~1.73 ps/(℃*km)
-0.87~ ps/(℃*km)
laser diode spectrum
temperature efficiency
G652.D Chromatic dispersion [ref] ITU-T
δ ∆ 𝑡𝑥𝑠
𝑜𝑓𝑓𝑠𝑒𝑡 =δ 𝑑𝑒𝑙𝑎𝑦 𝑠𝑚 =− δ ∆ 𝑡𝑥𝑠

8. WR deployment at YBJ@Tibet
ARGO, Yangbajin, Tibet, 4300m a.s.l.
48 electron detectors, 2 Muon detectors
GPS receiver, Rubidium frequency
4 WR switches with latest GW/SW
Customized node (spec. elec with WRPC)
GPS+Ru+GrandMaster ED MD
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9. WR deployment at YBJ@Tibet
WRS
50/80m fiber GM Ru
GPS
ED assembled
50/80m fiber
3 ED as telescope
9ED on-top of MD
100m optical power composite cable
Portable Calibrate-Node

10. Portable Calibrate Node
A Cute-WR inside box, water sealed, vibration protect
Armored optical power composite cable
Rugged composite connector
reference PPS for field measurement
Directly connected to/synced with Grand-Master switch

11. WR-Switch GM vs PCN WRS1,2,3 vs PCN Over 20 hours, temp range 10-26℃
PCN with temp. correction, WRS without
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12. WR node 300 samples for each node Nodes in different locations
Node index
Node vs PCN (ps)
Accuracy
precision 2
-138
100 5
-56 28 8 12
-27
150 16 17
-15
162 24 97
156 32
-40 34 39
-28 41 42
-157
135 44
-102 26 50
-45
300 samples for each node
Nodes in different locations
WR integrated with detector electronics (ED & MD type)
WRPC as IP core
Node has been calibrated individually
Power noise causes bad precision

13. WR deployment at YBJ@Tibet : issues
Slave can’t follow time jump of master (known)
TAI vs UTC
DAQ-PC is running with UTC time, WR-timestamp is in TAI mode. Confusing?
RTU flushing takes time??
WR-time-get response late!
Net-port based status monitor
Packet lost
Fix-delay changes after P&R
WRPC as netlist blackbox is not enough.
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14. WR deployment at YBJ@Tibet
WR is promising
No serious issue, excellent experience.
~100ps accuracy with individual calibration
VERY tough environment
Temp, rain/snow, dust, rude operation, animal
PCN is useful
TDC will be integrated (no need for oscilloscope)
Remote FLASH update / multiboot will be great
should be integrated into all WR nodes
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15. WR developments at THU Cute-WR with remote-updade / multiboot
General for all LHAASO WR-nodes
Cute-WR-DP
Redundant links for high reliability (parallel mode)
Mini-switch for cascade topology (chain mode)
Cute-WR with TDC
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16. WR node with TDC synchronized time tags for signals/events
Distributed TDC, event logger, many applications
delay chain based TDC (23ps rms)
Auto calibration, real-time temp. correction, Cyclone-II/Spartan-6/Vertex-4
Bin nonlinearity need to be calibrated
Auto calibration before measurement is desirable
Random input signals
only available in special applications
Dedicated calibrate signal
Special OSC / Cascade PLL
W.Jin RT2014: Uneven Bin Width Digitization & Cascade PLL
DNL
Histogram
In (bin)
LUT S
Out (ps)
Pulses with evenly spread timing relative to the TDC clock
DMTD helper-clock
WR-clock
Get it for free, Bonus of WR

17. other WR applications in China
CSNS (China Spallation Neutron Source)
Apply WR for T0 arrival time measurement
~50 nodes, 2KM distance, 50ps time resolution
JUNO (Jiangmen Underground Neutrino Observatory)
apply WR for under-water readout-box time-sync
~1000 nodes, 150m distance,
fiber must be LS compatible
under water connectors, high reliability
ADS (Accelerator Driven Sub-critical System)
Apply WR as event logger for beam protect system
10 nodes, 200m distance, high reliability
CJPL (China Jinping Underground Laboratory）
Deepest underground lab, 7500 M.W.E.
Dark-matter / Neutrino experiments, low background facilities
General time/frequency distribution for 9 experiment halls
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18. Introduction to Ultrasync
Academic spin-off of THU
New partner in OHWR community
Current:
OHWR distributor (import/export)
Cute cards production
WR consultation & promotion in China
Future:
WR related development
WR installation/commission/maintainess
under construction
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19. sweet!
White Rabbit is synchronous, precise, robust and