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White Rabbit in radio interferometry
E Paul Boven1,2,3, Jeroen C J Koelemeij4,5, Chantal van Tour4,5
1JIVE - Joint Institute for VLBI ERIC, Oude Hoogeveensedijk 4, Dwingeloo, 7991PD the Netherlands.
Experimental Astronomy
|January 6, 2026
Summary
The White Rabbit protocol precisely distributes time and frequency signals over optical fibers, proving suitable for radio interferometry clock synchronization. This technology supports observing frequencies up to 15 GHz, enhancing telescope coherence.
Area of Science:
- Astronomy and Astrophysics
- Network Engineering
- Signal Processing
Background:
- Radio interferometry requires precise time and frequency synchronization for coherent operation.
- High-speed communication networks offer potential for distributing these signals.
- The White Rabbit protocol is designed for accurate time and frequency distribution over optical fibers.
Purpose of the Study:
- To evaluate the quantitative limits of the White Rabbit protocol for synchronizing radio interferometers.
- To develop a method for quantifying sensitivity loss due to White Rabbit phase noise.
- To assess White Rabbit's suitability for clock distribution in radio astronomy.
Main Methods:
- Developed a method to quantify coherence loss from White Rabbit phase noise, including a new expression for flicker phase noise.
- Designed a calibration procedure to measure dispersion in deployed fiber networks.
- Integrated White Rabbit into a production network with coexisting data traffic and conducted Very Long Baseline Interferometry (VLBI) experiments over 35 km and 169 km fiber links.
Main Results:
- Quantified coherence loss due to White Rabbit phase noise, showing good agreement between predicted and measured values.
- Demonstrated successful co-existence of White Rabbit signals with data traffic on the same fiber.
- Identified that standard White Rabbit v3 switches support up to 3.5 GHz, while low-jitter versions support up to 15 GHz.
Conclusions:
- White Rabbit is a viable solution for clock distribution in radio interferometry.
- The developed methods for quantifying coherence loss and measuring dispersion are effective.
- White Rabbit enables high-frequency observations in radio astronomy through precise time and frequency synchronization.
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