The Open Traceable Time Platform and applications in ...
Transcript of The Open Traceable Time Platform and applications in ...
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The Open Traceable Time Platform
and applications in finance and
telecommunications
Michael Wouters (NMIA)
Louis Marais (NMIA)
Amitava Sen Gupta (NPLI)
Ahmad Sahar bin Omar (NMIM)
Piyaphat Phoonthong (NIMT)
TCTF Workshop “Applications of T&F in finance and
telecommunications”, Singapore, 23rd November 2018
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The Open Traceable Time Platform
www.openttp.org
A fully open platform for developing
time and frequency services with
timing signals traceable to national
standards
A complete hardware and software solution that aims
for a turnkey experience.
https://github.com/openttp
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Why Open Source ?
Auditability Access to all system operational data,
at the level of raw measurements, to
prove that it was working correctly
Traceability Access to the full measurement and
analysis chain
Co-operation Leverage limited (and decreasing)
resources
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Hardware and timing signals
GPS
receiver
time-interval
counter
GPS-
disciplined
oscillator
single board
computer
time of day
1 pps
NTP 1 pps
10 MHz1 pps
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Single-board computer: BeagleBone Black
• 32 bit,1 GHz ARM processor
• dual 200 MHz realtime coprocessors
• 512 MB RAM
• running Debian Linux
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GPS receiver: NVS NV08C-CSM
• GPS/GLONASS/Galileo
• 32 channel
• 2 UARTS
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GPSDO: Jackson Labs LTE-Lite
When unlocked, and operated in an
environment where the temperature
is controlled to ±0.5 °C, the GPSDO
drifts by about 1 ms over 5 days.
TCXO
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FPGA: Opal Kelly XEM6001
USB interface
TICS are 200 MHz counters so
only 5 ns resolution.
Potential to improve this
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Stability and accuracy of time-transfer
splitter
Septentrio
PolaRx4TRPRONVS NV08C
UTC(AUS)
TIC
1 pps
1 pps10 MHz
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Stability of the computer’s time
GPSDO timestampGPIO
1 pps
/dev/pps0
ntpd disciplining
time constant (16s)
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Accuracy of the computer’s time
GPSDO IRQ raisedGPIO
1 pps
IRQ handler called
system time
requested for
timestamp
about 5 µs
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NTP load testing
PC
OTTP
direct connectiont
40,000 pkt/s
0
pac
kets
/s 8000 pkt/s
Use ntpd’s remote management facilities to gather statistics
ntpd becomes unresponsive and statistics can no longer be collected
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Response of the system to a step increase of 104
packets/s in the NTP load
on off
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Application: traceable time of day for telecomms
charging and billing systems
TelecommunicationsAustralian Communications Industry Forum Code of Practice:ACIF C518:2006 Call charging and billing accuracywww.acma.gov.au
Tolerance levels – Billing accuracy Parameters
Billing accuracy Test call tolerances
Parameter Untimed Timed
Call start time error +8.5,-5.5 s +8.5, -5.5 s
Call duration error n/a +1.5,-2.5 s
(from Table 3.1, pg 10)
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Application: auditing of NTP time of day
OTTP
time server
time server
time server
Customer may already have existing NTP infrastructure for their network.
Advantages of auditing rather than direct provision of time:• not a critical piece of infrastructure• change management is simpler• less complicated management software• less risk !
NTP
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NTP exchange
T1
T2 T3
T4
unit under test
auditing system
mean offset = [(𝑇2 − 𝑇1) + (𝑇3 − 𝑇4)]/2
round trip time = 𝑇4 − 𝑇1 − (𝑇3 − 𝑇2)
The uncertainty in the mean offset is half of the round trip time
Other information available –NTP stratum, accuracy, leap second indicator
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NTP measurements on a LAN
Audited system is a GPS-referenced NTP appliance
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Required synchronization accuracies
Gateway to gateway latency UTC accuracy Timestamp precision
> 1 ms 1 ms < 1 ms
<= 1 ms 100 µs < 100 µs
MiFID II requirements (European Union)
9.3.1 Market operators to synchronise clocks
(1) A Market operator must set the clock the Market operator uses for recording the time and date in its trading, compliance monitoring and reporting systems so that it is synchronised to within 20 milliseconds of the UTC(AUS).
(2) Where a Market operator relies on another person to provide any aspect of their trading, compliance monitoring or reporting systems that records the time and date, the Market operator must take reasonable steps to ensure that person synchronises the clock used for that purpose to within 20 milliseconds of the UTC(AUS).
ASIC requirements for financial markets (Australia)
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Department of Industry, Innovation and Science | National Measurement Institute
36 Bradfield Rd
Lindfield NSW 2070
Australia
Telephone +61 2 8467 3501
Thank you for your attention!