Author: Bassanese, S.
Paper Title Page
TUOC01 Integration of a Pilot-Tone Based BPM System Within the Global Orbit Feedback Environment of Elettra 190
 
  • G. Brajnik, S. Bassanese, G. Cautero, S. Cleva, R. De Monte
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
 
  In this contribution, we describe the advantages of the pilot tone compensation technique that we implemented in a new BPM prototype for Elettra 2.0. Injecting a fixed reference tone upstream of cables allows for a continuous calibration of the system, compensating the different behaviour of every channel due to thermal drifts, variations of cable properties, mismatches and tolerances of components. The system ran successfully as a drop-in substitute for a Libera Electron 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 (at 10 kHz data rate) for the pilot tone position was less than 200 nm on a 19 mm vacuum chamber radius, with a long-term stability better than 1 um in a 12-hour window. 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.  
slides icon Slides TUOC01 [6.468 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-TUOC01  
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TUPB13 Stability Tests with Pilot-Tone Based Elettra BPM RF Front End and Libera Electronics 289
 
  • M. Cargnelutti, P. Leban, M. Žnidarčič
    I-Tech, Solkan, Slovenia
  • S. Bassanese, G. Brajnik, S. Cleva, R. De Monte
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
 
  Long-term stability is one of the most important properties of the BPM readout system. Recent developments on pilot tone capable front end have been tested with an established BPM readout electronics. The goal was to demonstrate the effectiveness of the pilot tone compensation to varying external conditions. Simulated cable attenuation change and temperature variation of the readout electronics were confirmed to have no major effect to position data readout. The output signals from Elettra front end (carrier frequency and pilot tone frequency) were processed by a Libera Spark with the integrated standard front end which contains several filtering, attenuation and amplification stages. Tests were repeated with a modified instrument (optimized for pilot tone) to compare the long-term stability results. Findings show the pilot tone front end enables great features like self-diagnostics and cable-fault compensation as well as small improvement in the long-term stability. Measurement resolution is in range of 10 nanometers RMS in 5 Hz bandwidth.  
poster icon Poster TUPB13 [1.223 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-TUPB13  
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