Operation and performance of a longitudinal feedback system using digital signal processing

A programmable longitudinal feedback system using a parallel array of AT&T 1610 digital signal processors has been developed as a component of the PEP‐II R&D program. This system has been installed at the Advanced Light Source (LBL) and implements full speed bunch by bunch signal processing for storage rings with bunch spacing of 4 ns. Open and closed loop results showing the action of the feedback system are presented, and the system is shown to damp coupled‐bunch instabilities in the ALS. A unified PC‐based software environment for the feedback system operation is also described.