The aim of this project is to create a Radio over Ethernet (RoE) protocol, which supports the transmission of Radio Frequency (RF) signals via an Ethernet network that can meet the stringent requirements of particle accelerators. Particle accelerator facilities often require two types of RF applications:

• Localised RF signal generation with picosecond level resolution to support the control and phasing of RF cavities.
• Facility wide distribution of this RF signal with sub-nanosecond resolution to monitor the particle beam. This enables beam synchronous applications to monitor the beam position and coordinate beam synchronous events.

These applications require that a new RoE protocol should enable:

• Phase alignment of the RF signal at a picosecond resolution.
• A frequency range from 1 MHz to 10 GHz.
• Support of beam synchronous events.
• An update rate of frequency and phase information up to 250 kHz.
• Multiplexing of simultaneous RF signal transmission in an Ethernet network.

Particle accelerator facilities require distribution of RF signals with < 50ps jitter and < 50 ps phase aliment (see Requirements). Achieving picosecond-level synchronization is a challenging proposition. An Ethernet network that provides picosecond resolution of Temps Atomique International (TAI), such as White Rabbit, is assumed to be deployed.

This project builds upon experience of distributing RF signals using White Rabbit Ethernet networks – commonly referred to as Radio Frequency over White Rabbit (RFoWR) – that have been developed by various research facilities, including European Organization for Nuclear Research (CERN, Switzerland/France), European Synchrotron Radiation Facility (ESRF, France), and Super Photon Ring – 8 GeV (SPring-8, Japan). All these facilities used Direct digital synthesis (DDS) to digitize and synthesize the transmitted RF signals (see Background)

Hitherto, whilst the concepts of the RFoWR protocol are understood and common to various implementations, they are nonetheless, different and incompatible with each other. A common standard-based protocol that is suitable for various research facilities will encourage re-usability, collaboration and provide long-term benefits.

We have identified an IEEE standard, namely IEEE 1914.3, the IEEE Standard for Radio over Ethernet Encapsulations and Mappings, as suitable for our objectives.

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