The Time and Frequency Laboratory of the Hellenic Institute of Metrology (EIM)

The Time and Frequency Laboratory of the Hellenic Institute of Metrology (EIM)

Dr Irene Flouda

Director of the Electrical Measurements Department

Hellenic Institute of Metrology

04/12/23 ΕΙΜ – DEM Time & Frequency Laboratory

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HISTORY

•Legal Metrology in Greece was established in early 30’s

•EIM founded in 1994 (law 2231/94) as the only NMI

•Fisrt building site completed in 1996

•Recruitement of staff started in late 1997

•Equipment set in operation gradually since 1998

•QS implementation started in 1999

•Offer of services since 2000

•Second building site completed in early 2001


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Management CouncilPresident and 6 Members

General Director

Director of Financial & Administrative

Services

Director of QualityAssurance

& Scientific Support

Director of Mechanical

Measurements Dept.

Director of Physical

Measurements Dept.

Director of Electrical

Measurements Dept.

Accounting

Personnel

Technical Support

Quality Assurance

Cooperation

Training

Mass

Density

Pressure

Force-Torque

Flow-Viscosity

Volume

Hardness

Temperature-Humidity

Dimensional

Acoustics-Vibrations

Optics-Photometry

Low Frequency

High Frequency

Time & Frequency

Secretariat

ORGANOGRAM


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Location

• The Time and frequency Laboratory is located at the new EIM building at Sindos, in Industrial area of Thessaloniki, GREECE.


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Laboratory

• Laboratory Area: 50 m2

• Environmental conditions: – Temperature: 23 ±0,5oC,

– Humidity: 50±10%

• Shielding: 60dB@10kHz, 100dB@100kHz-35GHz• Power supply: Stability 1% (10% variation of main

voltage), total harmonic distortion <2%

(TUV certified)


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Laboratory

• The laboratory has an entrance with double doors (air –

lock) in order to minimize the environmental variations

inside the lab.

• The floor is made of special material with antistatic

properties.

• Environmental conditions are monitored continuously.


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Scope– Activities

• Realization and dissemination of units.• Maintain Local Time Scale UTC(EIM).• Maintain frequency reference signals for use in various

activities of the institute.• Traceability to International Standards.• Calibrations of various instruments in the field.

– Chronometers– Frequency Counters– Cables, signal delays– Frequency standards– Vehicle speed measuring systems


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Scope– Activities

• Services of metrological support (training, consulting)

• Measurements for type approval of measuring devices

• Cooperation with other quality organizations

• International cooperation (EURAMET)

• Promotion of metrology (publications, presentations,

cooperation with Universities)


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Quality System

• The Lab procedures are covered by the QS

• Intercomparisons: – EUROMET TF.TI-K1 “Comparison of time interval

measurement”

• CMC’s: They will be submitted in 2008


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National Standard for Time and Frequency

1. Continuous and reliable local representation of Universal

Coordinated Time - UTC(EIM).

2. Contribution to Temps Atomique International (TAI).

3. Reliable and continuous distribution of reference

frequencies.

4. Traceability to the international standards.

5. Broadcast of standard time and frequency signals inside

and outside EIM facilities.


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System Configuration and Operation

• System architecture:

1. Atomic Standards

2. Time Recovery

3. Clock Measurement

4. Signal Distribution

5. Time dissemination


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Basic Equipment

1. Atomic Standards :

– 4 HP 5071A Opt.001 Atomic Frequency Standards.

• Widely spread commercially available atomic frequency

standard.

• Very Good stability in laboratory environment, can withstand

small variations in temperature

• Controlled by a computer (serial port )

– Three 5071A are incorporated in the UTC reference system.

– One for backup reasons.


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Basic Equipment

2. UTC Recovery System– TSC 2214 multichannel CV all in view receiver + Antenna

– electronics etc

3. Clock Measurement– Continuous Measurement of the Atomic Standards Phase

– Measurement of CS1-UTC difference which is fed to the steering algorithm.

– Measurement of the CS1-CS2 and CS1-CS3 difference for Clock Report


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Basic Equipment

4. Signal Distribution– 1 PPS, 5 MHz

– Distribution Amplifier: 100 kHz, 1 MHz, 10 MHz

5. Time dissemination

– Symmetricom S250 NTP server (ready to be activated as time.eim.gr).

– NTP server “homemade” (ntp.eim.gr).


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Time Dissemination

• NTP server “homemade” (ntp.eim.gr).– PC running UNIX serves as ntp.eim.gr NTP server.

– Synchronization with the UTC Reference System

– Between synchronizations the server uses the 5071A which is steered to the UTC.

• Symmetricom S250 NTP server – High reliability, can handle more traffic.

– Same principle of operation.

– Includes GPS receiver as a backup in case of system failure.

• Both systems are classified as Stratum Level 1 Servers.


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Auxiliary Equipment

• 3S Navigation GNSS-300T GPS/GLONASS receiver.

• Absolute Time 100A GPS Clock receiver.

• HP 58503B Multichannel GPS receiver

– Auxiliary reference equipment

– Used for reference or other various tasks.

• FLUKE PM6681R Frequency & Time Interval Counter

• Agilent 33250A Function Generator

• LIDAR calibration equipment


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Simplified Ensemble Description

GPS(TSC 2214B)

1 PPS, UTC(EIM)

Ethernet

Controller(TSC 2077E)

Clock Measurement10 MHz

10 MHz

Divider/Multiplier5 MHz

5 MHz Reference

Signal

10 MHz Reference

Signal

1 MHz Reference

Signal

5071AΕΙΜ CS-1

5071AΕΙΜ CS-3

5071AΕΙΜ CS-2

Antenna Lighting Arrestor

cable

Steering


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Simplified Ensemble Description

GPS(TSC 2214B)

1 PPS, UTC(EIM)

EthernetController(TSC 2077E)

Zero Crossing Detector10 MHz

Event Timer

10 MHz

Divider/Multiplier

5 MHz

5 MHz Reference

Signal

10 MHz Reference

Signal

1 MHz Reference

Signal

Reference Timer

5071AΕΙΜ CS-1

5071AΕΙΜ CS-3

5071AΕΙΜ CS-2

Antenna Lighting Arrestor

cable


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Operation

• One Atomic Standard is periodically steered to UTC while the other two are free running.

• Between successful steerings for the local time scale all standards are used for better statistics.

• In case of GPS failure local time scaled will be sufficient for several days, provided all three Atomic Standards are operating.

• In case of full system failure the local time scale will be based on one atomic standard.


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Non interrupting operation

1. First Level: Mains Electrical Protection. The EIM’s facilities’ electrical supply includes protection from over-voltage events and generators automatically engaged in case of power failure in the area (UPS).

2. Second Level: The system includes UPS capable of keeping the system “alive” for a few hours.

3. Third Level: The 5071A Atomic Standards include batteries that can keep them continuously operating for a few more hours.

The non – stopping operation of the apparatus is very important for the continuity of the time scale.


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Time Recovery Segment

• Responsible for a) retrieving UTC time from GPS b) generating a core set of signals steered to UTC (1

PPS, 1 MHz, 5 MHz, 10 MHz, NTP time).• The CV GPS receiver has been calibrated at

NIST.• Under normal operating conditions and

provided that no chances are made at the configuration (cable, antenna etc.) the recovery of UTC is within 10 ns RMS.


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Antenna Position

• The GPS antenna is at a fixed position, not far away from the lab (cable as short as possible) with a clear sky view.

• It includes a protective lightning arrestor.• The whole signal cathode (antenna, cable, arrestor,

connectors) was carefully calibrated at NIST. The signal delay was measured at 678.9 ns with 0.1 ns uncertainty. The system is adjusted for this value.

• On Site: A four hour survey with a C/A – P code GPS was performed. The results were analyzed in accordance to the SOPAC database (http://sopac.ucsd.edu/)


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Antenna Position

• The antenna coordinates as determined:

SOPAC Automatic Analysis Solution Report Job number: 68923

Multi-station analysis using MATE NOT1 LAMP, resulted in the following mean coordinates, valid on reference epoch 2006.9493 (2006 347):

Site Latitude (d) Longitude (d) Height (m) Stdev. (m) Stdev. (m) Stdev. (m) NIM3 40.68878635 22.79971642 53.2909 WGS84 0.0119 0.0131 0.0391

X (m) Y (m) Z (m) Stdev. (m) Stdev. (m) Stdev. (m) NIM3 4464808.4700 1876806.6594 4136313.3107 ITRF2000 0.0157 0.0292 0.0272


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GPS observations

-250

-200

-150

-100

-50

0

50

100

150

31-Ιουλ-07 7-Αυγ-07 14-Αυγ-07 21-Αυγ-07 28-Αυγ-07

Ημερομηνία

REFGPS

• GPS satellite #1 as tracked from the GPS receiver in August 2007, initial data REFSV (left) and REFGPS (right). Units are 0,1 ns.

-1.50E+06

-1.49E+06

-1.48E+06

-1.47E+06

-1.46E+06

-1.45E+06

-1.44E+06

-1.43E+06

-1.42E+06

31/7/07 0:00 7/8/07 0:00 14/8/07 0:00 21/8/07 0:00 28/8/07 0:00

Ημερομηνία

REFSV


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TAI contribution

• The controller records the difference of the free running standards with respect to the first one and produces the clock file for the BIPM.

GPSUTC(ΕΙΜ)

UTC

ΕΙΜ CS-1

ΕΙΜ CS-3

ΕΙΜ CS-2

Controller

UTC(ΕΙΜ) – CS2

UTC(ΕΙΜ) – CS3

BIPM

1431

0716


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Advantages – Disadvantages

+ High degree of electronic integration• Makes life easier and prevents from human mistakes.

• Provides monitoring tools for checking the data flow.

+ High efficiency• The overall performance of the system as well as the

performance in specific sectors.

+ High reliability• The local time scale is maintained continuously and the

deliverance of stable reference signals is reliable.

– Computers sometimes fail…• System may need restarting and this can move abruptly

the local time scale.


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UTC-UTC(EIM)

-10

-5

0

5

10

15

54300 54330 54360 54390 54420 54450 54480 54510

MJD

ns


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Local Time Scale UTC(EIM)

5x104 5x105 5x106

7,5E-151E-14

2,5E-14

5E-14

7,5E-141E-13

2,5E-13

2 Clock Ensemble 3 Clock Ensemble

Tot

al A

llan

Var

ian

ce

Aver. Time (s)

The Time and Frequency Laboratory of the Hellenic Institute of Metrology (EIM)

Technology

Transcript of The Time and Frequency Laboratory of the Hellenic Institute of Metrology (EIM)