The commissioning of the SLS FOFB has just started and first results have been presented. Its conceptional design could be successfully demonstrated. Focus during the first measurements was the commissioning of the feedback components rather than optimization of the performance.
To reach the FOFB design goals of integrated sub-micron orbit
stability up to 100 Hz in both planes, several improvements will be
accomplished during the further commissioning. An upgrade of the DDC
firmware to synchronize the 4 kHz BPM outputs will reduce the digital
feedback delay by 240 
s. Beside this, the data transfer from the
DSP to the power supply controller which presently takes place via the
IOC of the control system will be short cut. Both upgrades will reduce
the digital latency and consequently increase the loop
bandwidth. Optimizations of PID parameters are required to achieve
increased feedback performance. Recent laboratory studies have shown
the potential to reduce the BPM noise clearly below 1 m even at 2
kHz bandwidth. Furthermore, long term and power spectral densities
measurements at several locations especially close to the insertion
devices as well as X-ray BPM measurements will be necessary in order
to quantify the residual position RMS values of the orbit.