The purpose of the General Machine Timing System (GMT) is to trigger and synchronize equipment and software actions, timed according to the accelerator cycles. The timing system must handle machine cycles from milliseconds up to the order of several seconds for synchrotrons and up to several hours for storage rings. Beam manipulation phases may be as short as a few micro seconds. The timing system also must take real time decisions to decide correctly between predefined alternative cycles to be executed.

The GMT triggers and synchronizes about 3000 connected Front-End Controllers (FEC) and other equipment covering a distance of up to 2 km between the nodes in the timing network. Although a precision of 1 µs is sufficient in most cases, some equipment like kickers need timing with nanosecond precision. An important issue is the link between the GMT and the timing system of the existing facility.

The GMT is implemented using White Rabbit which is an extension of Ethernet based on PTP and specific hardware for clock and phase synchronization. The GMT is complemented by the Bunch phase Timing System (BuTiS), which is a high-precision clock distribution system mainly targeted at the radiofrequency systems of the accelerator.

More information is available at Wiki