A new-concept BPM was developed to prove the usefulness of pilot tone technique in channels equalization, thermal drift compensation and self-calibration.
It ran successfully not only during various machine shifts, but also during a user dedicated beamtime shift for more than 10 hours, behaving in a transparent way for all the control systems and users. The equivalent RMS noise (10 kHz data rate) for the pilot tone position was less than 200 nm on a 20 mm vacuum chamber radius.
Two main steps led to this important result: firstly, the development of a novel RF front end that adds the pilot tone to the signals originated by the beam, secondly, the realisation of an FPGA-based double digital receiver that demodulates both beam and pilot amplitudes, calculating the compensated X and Y positions.
We successfully tested our system as a drop-in substitute for Libera Electron systems, by placing our front end inside the machine tunnel, connected on one side to the button BPMs of a section normally used by a Libera, and on the other side to the digital receiver. We also demonstrated seamless communication via Ethernet interface with the global orbit feedback and Tango control systems.