Compensating the frequency deadband of the APS real-time and DC transverse orbit correction systems

Currently, two parallel feedback systems correct the transverse Advanced Photon Source (APS) orbit in both planes: a workstation-based slow (DC) system and a realtime system (RTFS) that samples at 1.6 kHz. A partial solution to preventing feedback-system crosstalk has been to bandlimit the RTFS from below, but this fix has borne a system deadband in which little orbit correction is achieved. We present a matrix time-domain compensation algorithm that greatly reduces the system deadband, as well as operational data.