Transcript NMISA Technical Progress Report 2010 by Rheinhardt Sieberhagen

NMISA Technical
Progress Report 2012
Adriaan van Brakel
© NMISA 2012
Time and Frequency Laboratory
 Who are we?
 Chris Matthee: Section Head (Time, Frequency and Fibre Optics); R&D Metrologist
[email protected]
 Adriaan van Brakel: R&D Metrologist (Time and Frequency; Fibre Optics)
[email protected]
 Thembelani Gina: DST-NRF Intern (Time and Frequency; Fibre Optics)
 Overview:
 Location: NMISA, CSIR Campus, Pretoria, Gauteng, South Africa
 Only contributor to UTC in Southern Africa (one of only two in Africa)
 Standards maintained at better uncertainties than local industry requires
© NMISA 2012
Key infrastructure and UTC(ZA)
 Local frequency standard:
 Consists of four commercial, thermal beam caesium atomic clocks
 One high-performance tube, three long-life tubes
 Pre-emptive tube replacements done to prevent simultaneous clock failures
 Used to realise the South African National Timescale (SAST)
 Time transfer link:
 Septentrio PolaRx3eTR multi-frequency geodetic
receiver (GPS and GLONASS)
 Currently submit CGGTTS data to BIPM; aim to submit
RINEX data soon.
 UTC(ZA):
 Currently based on a single clock (inventory TF0004)
 Maintained to within 5 µs of UTC: time step as required
 Monthly average frequency error is between 1,1·10-13
and 0.8·10-13 (expected error is 1,4·10-13)
© NMISA 2012
Traceability
 Measurement parameters:
 Frequency (and rotational speed): direct comparison against local
standard, or indirectly via calibrated phase-locked counters or generators
 Time interval: measurements performed with counters phase-locked to
local frequency standard
 Phase angle: measurements performed with verified Clarke-Hess 5500
phase angle generator
 Rise- and fall-time: imported traceability: pulse source calibrated by PTB
© NMISA 2012
Accreditation and CMCs
 Accreditation:
 Accredited by the South African National Accreditation Service (SANAS)
since July 2003
 Previous technical assessors:
 Dr Peter Fisk (NMIA);
 Dr Bruce Warrington (NMIA);
 Dr P. Banerjee (NPLI).
 Most recent re-assessment: August 2011
 Accreditation renewed for: frequency, time interval, rise- and fall-time,
phase angle, and rotational speed (contact and non-contact)
 Calibration and Measurement Capabilities:
 Listed on BIPM KCDB since January 2011
 CMCs for:
 Frequency;
 Rise- and fall-time;
 Time interval (delay).
© NMISA 2012
Research and development
 Steering of local frequency standard
 Comply with BIPM requirement to keep UTC(ZA) within 100 ns of UTC
 Design of auxiliary offset generator and commission with clock ensemble
 Design and implementation of clock steering algorithm
 Table-top optical frequency standard
 Focus is on portability, maintainability and robustness
 Based on two-photon transition of rubidium atom
 Fibre laser-based source is being constructed
 Other research interests:
 Frequency generation and transfer in radio astronomy
(MeerKAT → Square Kilometre Array);
 Time tagging of electronic events;
 Time and frequency transfer techniques, towards African
timing network and regional comparisons (AFRIMETS);
 Development of stand-alone systems for low accuracy
T&F transfer and remote calibration.
© NMISA 2012
© NMISA 2012