Technology and First Beam Tests of the New CERN-SPS Beam Position System

The CERN Super Proton Synchrotron (SPS) uses 215 beam position monitors (BPMs) to observe the beam orbit when accelerating protons or ions on a fast ramp cycle to beam energies of up to 450 GeV/c. In the frame of the CERN LHC Injector Upgrade (LIU) initiative the aged, and difficult to maintain homodyne-receiver based BPM read-out system is currently being upgraded with A Logarithmic Position System - ALPS. As the name indicates, this new BPM electronics builds upon the experience at CERN with using logarithmic detector amplifiers for beam position processing, and is well suited to cover the large range of beam intensities accelerated in the SPS. The system will use radiation tolerant electronics located in close proximity to the split-plane or stripline beam position monitor with GB/s optical data transmission to the processing electronics located on the surface. Technical details of the analog and digital signal processing, the data transmission using optical fibers, calibration and testing, as well as first beam tests on a set of ALPS prototypes are presented in this paper.