Both the ATLAS and CMS Collaborations are planning to install new detectors designed to measure the time of arrival of particles produced at the CERN LHC to a precision of 30 ps or better.
An essential component of any of these detectors is the reference clock that has to be distributed to multiple sites across the detector, aligned to better than 10 ps. This report describes a clock distribution system suitable for these large scale applications and the demonstration of the achievement of an inter-clock stability of less than 1 ps.