The Orbit Measurement System for the CERN Extra Low Energy Antiproton Ring

The CERN Extra Low ENergy Antiproton ring (ELENA) intended to decelerate anti-protons from the CERN Antiproton Decelerator from 100Mev/c to 13.7MeV/c, has been equipped with an orbit measurement system consisting of 10 horizontal and 10 vertical electrostatic pick-ups. Using charge amplifiers the signals are converted into sum and difference signals that, once digitalized, are down converted to baseband and used to calculate intensity independent beam positions. The system is implemented on seven VME switched serial based FPGA / DSP boards carrying direct digital synthesisers and analogue to digital converters on standard FPGA mezzanine cards. The switched serial high-speed bus allows intercommunication between DSPs and thus averaging of the signals from all pick-ups in real-time to be used either in the RF radial feedback system or for longitudinal Schottky diagnostics. The system implementation and initial orbit measurements with the H⁻ beam used for ELENA commissioning will be presented, as well as future upgrades for trajectory and longitudinal Schottky measurements.