7-11-2014: VLBI workshop presents 4 x WR
The Third International VLBI Technology Workshop will feature four presentations (out of 55) and one poster that feature White Rabbit.
These workshops, which evolved from the highly successful 10-year series of International e-VLBI workshops, aim to encompass all areas of hardware or software development relevant to VLBI.
RadioNet3 ERATec Engineering Special Session
hosted by the Joint Institute for VLBI in Europe
10 - 13 November 2014, Groningen/Dwingeloo, the Netherlands
http://www.jive.nl/ivtw2014/abstracts.php
Presentations
| Author | Title and Abstract |
|---|---|
| Boven, Paul | Title: Using VLBI to demonstrate long-haul fiber-optic frequency transfer |
| Abstract: | |
| Time transfer over fiber optic links opens two exciting possibilities for VLBI. Firstly, it enables the dissemination of an even higher quality clock to observatories, compared to the performance of the H-masers commonly in use. This can improve the sensitivity in e.g. space-based VLBI and astrometry. It will also do away with the need to perform clock-searches. Secondly, it allows to deliver a frequency reference with suitable stability for VLBI, to telescopes that do not have (the budget for) an H-maser. This would make it possible to expand the VLBI arrays with e.g. telecon dishes converted for radio astronomy. An interesting use case of this is the nascent African VLBI Network. | |
| In the Asterics proposal that we recently submitted, we hope to demonstrate the feasibility of using White Rabbit to transfer the WSRT H-maser signal via fiber optics to the Dwingeloo Radio telescope, and measure fringes between these two telescopes. | |
| Jansweijer, Peter | Title: Implementing White Rabbit in your design |
| Abstract: Distribution of time throughout large infrastructures has been an issue for many decades. In recent years work has been done by the White Rabbit developers community to provide a fully deterministic Ethernet-based network for general purpose data transfer and synchronization at sub-nanosecond accuracy and picoseconds precision for large distributed systems. White Rabbit enhances the Precision Time Protocol (PTP) and is currently the most accurate PTP implementation. | |
| White Rabbit has got the attention of many people, and today the number of users and applications in different fields, worldwide, is increasing. | |
| Following a brief overview of White Rabbit, this talk will explain how to make your own hardware White Rabbit capable. It will mainly focus on the technical aspects of such an implementation. | |
| Koelemeij, Jeroen | Title: Methods for data, time and ultrastable frequency transfer through long-haul fiber-optic links |
| Abstract: | |
| Tightly synchronized time and frequency references are essential for astronomical observations via distributed antenna arrays, such as VLBI. Typical synchronization solutions make use of GPS radio signals and/or stand-alone atomic clocks like hydrogen masers. Recently, several research groups have developed and demonstrated fiber-optic methods for time and frequency distribution over long distances. The unsurpassed stability and accuracy afforded by these methods opens up the perspective of future fiber-optic infrastructure providing high-capacity telecommunication along with atomic clock signals of extremely high quality. A promising approach into this direction is the White Rabbit (WR) protocol developed at CERN, which combines Gigabit Ethernet with time transfer with 1 nanosecond uncertainty over distances up to 10 km. In this talk I will describe a WR link between the cities of Amsterdam and Delft in the Netherlands, aimed at sub-nanosecond time transfer over 2×137 km of installed optical fiber. The link employs bidirectional semiconductor optical amplifiers, and the outcome of a performance comparison with erbium-doped fiber amplifiers is reported. Finally, I will discuss the possibility of implementing WR for (e)VLBI observations in existing dense-wavelength-division-multiplexed networks. | |
| Wallin, Anders | Title: Time Transfer in a Wide Area White Rabbit Network |
| Abstract: | |
| Time transfer using the White Rabbit Precision Time Protocol (WR-PTP) is demonstrated over a 1000 km optical fiber link using a dedicated channel in the Finnish University Network (FUNET). The maximum instability of time transfer, determined by independent GPS-PPP measurements, was +/-2 ns over a 100 day period. We discuss the performance and limitations of WR-PTP time&frequency transfer in a public NREN. | |
| The performance of a 5 km actively compensated frequency distribution link using semiconductor and erbium-doped fibre amplifiers is also described, which enables state-of-the-art frequency comparisons for tests of fundamental physics in widely separated experiments. This technique can be employed on the 2x317 km optical fibre link between VU Amsterdam and University of Groningen. |
Poster
| Author | Title and Abstract |
|---|---|
| Pinkert, Tjeerd | We report on a new fibre-optic link for time distribution with (sub-)nanosecond uncertainty and dissemination of the SI second, which has been realized between VSL Delft and Nikhef Amsterdam. We make use of quasi-bidirectional semiconductor optical amplifiers, instead of commonly-used erbium doped fiber amplifiers, to enable bidirectional optical transmission out of the C-band. Such links, based on commercially available White Rabbit Ethernet technology developed at CERN, can be used to augment or surpass time distribution by Global Navigation Satellite Systems, aiming at applications in telecommunication, the electricity grid, finance, and ‘SuperGPS’ positioning. |