Signal Processing Architecture for the HL-LHC Interaction Region BPMs

In the HL-LHC era, the Interaction Regions around the ATLAS and CMS experiments will be equipped with 24 new Beam Position Monitors (BPM) measuring both counter-propagating beams in a common vacuum chamber. Numerical simulations proved that, despite using new high-directivity stripline BPMs, the required measurement accuracy cannot be guaranteed without bunch-by-bunch disentanglement of the signals induced by both beams. This contribution presents the proposed signal processing architecture, based on direct digitisation of RF waveforms, which optimises the necessary computing resources without a significant reduction of the measurement accuracy. To minimise the number of operations performed on a bunch-by-bunch basis in the FPGA, some of the processing takes place in the CPU using averaged data.