TTC distribution for LHC detectors

At each of the CERN LHC experiments, timing, trigger and control (TTC) signals must be distributed to numerous electronic systems from a single location in the vicinity of the central trigger processor. A multichannel optical distribution system has been developed which can broadcast the signals to several thousand destinations from a few relatively high power laser sources over a passive optical fiber network with uncontrolled path lengths. The system delivers the LHC timing reference and first-level trigger decisions with the corresponding bunch and event numbers. It incorporates facilities to compensate for particle flight times and detector, electronics and propagation delays. In addition it provides for the simultaneous transmission of synchronized broadcast commands and individually-addressed controls and parameters, such as channel masks and calibration data