Dwingeloo Telescope has Fringes (Again)

Abstract

The Cleopatra work package of the ASTERICS project aims to address the common challenge of time and frequency distribution in distributed instruments and multi-messenger astronomy. We have made improvements to the open hardware 'White Rabbit' time and frequency distribution system to achieve better reach, stability and phase noise. Moreover, we are able to use White Rabbit over public fiber, co-existing with other traffic on different wavelengths. To demonstrate the achieved performance, we are conducting VLBI observations using the venerable Dwingeloo telescope, which will soon be connected to the hydrogen maser reference from the Westerbork Synthesis Radio Telescope, transported over 165 km of fiber in the SURFnet network. Using offthe-shelf software-defined-radio hardware, and the open-source GNU Radio program, we have recently achieved our first fringes between Westerbork, Jodrell Bank and Dwingeloo.

A hybrid optical–wireless network for decimetre-level terrestrial positioning

“…Well developed methods [27][28][29] exist to calibrate such delay asymmetries, making it is possible to synchronize WR devices to within a fraction of a nanosecond even over distances in excess of 100 km (refs. 30,31 ). Therefore, our TNPS might be used to broadcast national realizations of utc over the air with subnanosecond uncertainty, an improvement over common GNSS time distribution techniques by two orders of magnitude 32 .…”

“…Such wavelengths are often available as they are less suitable for high-capacity data transmission systems. Employing wavelength division multiplexing (WDM), WR operating in such unused wavelength bands has already been successfully integrated into long-distance fibre-optic networks that simultaneously carry live high-capacity data traffic, showing no interaction between the WR signals and the other data traffic, and achieving subnanosecond timing performance 30,31,34 . Second, our TNPS system may be implemented in ways that circumvent the scarcity of radio BW.…”