Switched reference phase lock loop (SRPLL)

The Brookhaven National Laboratory Relativistic Heavy Ion Collider (RHIC) has two beam synchronous event links (BSL), one for each ring, which use the 28 MHz ring low level RF to distribute event codes synchronously with a precise phase relationship to the beam. During a cogging reset just before injection, the low level RF sine wave is interrupted which causes the BSL receivers to lose lock. Lock loss in turn causes false triggers and other undesirable effects on the beam position monitors (BPM), ionization profile monitors (IPM), the tune meter and various experiments which use the BSLs. To rectify these problems, a SRPLL has been inserted between the beam synchronous master and the low level RF source. The SRPLL inserts a frequency and phase continuous splice over the dead-band gap in the RF source created during a cogging reset. The splice removes the gap and prevents the distributed BSL receivers from losing lock