Development of improved and scalable calibration techniques for PTP-WR fibre links (Objective 1)

A first calibration workshop has been organised by the consortium and held at NWO-I, where NWO-I demonstrated their new calibration setup for electrical-electrical calibration of WR-devices, and for electro-optic calibration of transceivers. VTT has started developing similar setups, carrying out field-tests on the Otaniemi-Metsähovi testbed, including verification measurements using GPS-PPP.

Development of validated techniques for redundant and resilient PTP-WR time transfer to industrial end users (Objective 2)

The consortium identified different topologies, mechanism and features to improve the resilience of the WR-PTP technique. This is the first step towards the suggestion of a systematic design to improve reliability of the time dissemination over extended and continuous implementations in real links.

Development of a next generation of PTP-WR devices with improved performance and high-compatibility interfacing with industrial applications (Objective 3)

The consortium completed the analysis of single components to be improved to increase the overall performances of WR-PTP devices. In particular, WRITE tested alternative Local Oscillators and now the new design of the board is well advanced.

Demonstration of the use of PTP-WR to deliver UTC(k) time scales and frequency in the RF domain from NMIs to industrial users and evaluation of the end-to-end uncertainty of the established time transfer (Objective 4)

The consortium started to design and develop in-field optical link to implement WR-PTP dissemination towards industrial partners and to host new devices in the second part of the project. The architecture of four test-beds has been developed, and two test-beds were established in Italy and Sweden.

Progress beyond the state of the art

This project will advance the state of the art in PTP-WR by establishing the metrological capacities required to accelerate the industrial adoption of PTP-WR for time transfer. Cost effective solutions will be developed which can be integrated with existing fibre networks devoted to internet communication, allowing industry to receive a time reference signal traceable to UTC without extra costs related to new infrastructures and with the resilience and reliability typical of telecommunication services.

Improved and scalable calibration techniques for PTP-WR optical fibre links will be developed, including the calibration and characterisation of the internal delays within devices and their dependence on external factors (e.g. temperature), and differential propagation delays through the optical fibre. The target uncertainty for device calibrations is 200 ps and 1 ns – 2 ns for propagation-calibration for fibre link lengths up to 1000 km, placing PTP-WR at the same level as state-of-the-art Two way Satellite Time and Frequency Transfer time transfer, compared with the current state-of-the-art uncertainty in industrial applications of around 100 ns.

Many industrial applications require high reliability and resilience. This project will develop redundant and resilient features for time transfer for industrial use, such as redundant links from multiple time sources to one user, and improved resilience by providing alternative clock sources (e.g. time link, local clock, and GNSS signals) and enhanced performance levels. Although similar redundancy and resilience measures have been implemented with classical PTP, the PTP‑WR implementation by this project will, for the first time, enable reliable and standardised time distribution with better performance than GNSS methods.

Two important interfaces for PTP‑WR are the time and frequency outputs, and in addition low phase noise, low timing jitter and fast rise time are highly desirable features. This project will investigate the use of low-noise local oscillators and improved circuitry to obtain sharply defined waveforms, with the goal of achieving a frequency instability of ADEV <1×10 13 at 100 s integration time. A third essential interface with industrial applications is formed by the PTP‑WR optical outputs themselves, which are backward compatible with PTP (IEEE 1588-2008), but not with all the different PTP profiles that have been created for various different industries. The project will develop devices that are broadly backwardly compatible with existing industrial protocols and standards.

This project aims to boost the availability and uptake of WR UTC services. Firstly, it will develop methods (such as modified “three-cornered-hat” comparisons) which allow the assessment of fibre link stabilities even if comparative links are not available. Secondly, it will demonstrate the viability of WR UTC services by connecting three NMIs to industrial users active in the space industry and telecommunications through (redundant) fibre-optic links that also carry regular transport data, in order to demonstrate a durable and robust time and frequency transfer process, to test the real Technology Readiness Level, to accelerate the uptake of the IEEE1588-2018 High Accuracy profile, to be published, and to demonstrate the routine use of PTP-WR by a high-level European industry.


M9 Progress Meeting

11-12 March 2019

A consortium meeting to assess WRITE progress at month 9 was held at NIKHEF, Amsterdam.

Euramet Technical Committee for Time and Frequency

7-8 March 2019

Dr. Anders Wallin presented WRITE on behalf of the Consortium at the  Euramet Technical Committee for Time and Frequency meeting  at NPL, Teddington.

WP1 Calibration Bootcamp

12–16 November 2018

WP1 Calibration Bootcamp

Attendees gained hands-on experience with the calibration devices and other instruments required for White Rabbit calibrations. It was discussed how calibration devices and setups could be replicated by the other WRITE partners in their home laboratories. The documentation of calibration techniques (WP1 deliverable) was started. WRITE participants from VTT, INRiM, NPL, 7Sols and OPNT attended the bootcamp.

A hands-on ‘calibration bootcamp’ took place at Nikhef in Amsterdam on 12–16 November 2018. The motivation was to transfer knowledge that Nikhef has on absolute calibration and delay-propagation calibration to other (mainly WP1) WRITE partners.

10th White Rabbit Workshop

6–7 October 2018

The 10th WR workshop was held at CERN, Geneva (Switzerland) on 6–7 October 2018.

Topics included WR technology evolution, applications and the process of standardisation under IEEE 1588.

View full meeting report