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Phase Profile Analysis for ADC Correction with IIR Filter - Jack Roberts Overview

Dive into phase profile plots, calibration techniques, and ADC droop correction with Jack Roberts. Explore unfiltered vs filtered phase reconstruction, pulse stability, and more. Learn about the IIR filter, exponential fit for ADC droop, and resolution comparisons for optimized results. Stay updated on the latest developments in data analysis and future considerations outlined by Jack Roberts.

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Phase Profile Analysis for ADC Correction with IIR Filter - Jack Roberts Overview

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  1. FONT Meeting 2nd August 2013 CTF3 May 2013 Data Analysis Phase Profile Plots and ADC Droop Correction with IIR Filter Jack Roberts

  2. Overview • Phase profile with unfiltered Mixer/Diode. • Calibration with IIR filter, Mixer/sqrt(Diode). • Phase profile with filtered, Mixer/sqrt(Diode). • Unfiltered vs. Filtered phase reconstruction. • Mean pulse to pulse phase stability. Jack Roberts

  3. Recap: Unfiltered Mixer/Diode Calibration CALIBRATION LO SCAN • Cancel ADC droop by using Mixer/Diode instead of Mixer/sqrt(Diode). • Absorb beam current A in to calibration constant a. • Fitted values for a: • M1: 1.67 • M2: 3.11 • M3: 1.92 • Best resolution near zero crossings of LO scan. • Plots for the points circled here are outlined in red. • All the plots are mean subtracted. 9 4 3 8 Jack Roberts

  4. Phase Profile – No filtering, Mixer/Diode Calibration. Jack Roberts

  5. Phase Profile – No filtering, Mixer/Diode Calibration Jack Roberts

  6. Phase Profile – No filtering, Mixer/Diode Calibration • Good agreement between M1 and M3 near zero crossings of ADC output in LO scan. • Saturation effects near min/max of ADC output in LO scan due to sin(phi)>1 values. Jack Roberts

  7. ADC Droop Exponential Fit • Fit an exponential to the diode data then use the fitted decay constants in an IIR filter: • Fitted values for τ (in 357 MHz samples), Diode ADCs: • M1: 518 ± 1 • M2: 440 ± 1 • M3: 457± 2 • Also have droop in mixer channel but can’t fit exponential to it. • Use the mean of the diode ADCs: τ = 472. • Can get these values from lab tests (on going). • Fitted values for τ can vary up to ~20% dependent on sampling window used, LO phase etc. • Resolution seems fairly insensitive to τ. Jack Roberts

  8. ADC Droop Exponential Fit • Left: Points are mean diode channel data for each LO phase setting. Black lines are the exponential fit using the fitted decay constants. • Seeing cross-talk from Mixer? Jack Roberts

  9. IIR Filter • Implement an IIR filter to remove the exponential droop using the fitted decay constants: • Can now perform a calibration using Mixer/sqrt(Diode) as planned: • Fitted values for a: • M1: 52.5 • M2: 84.1 • M3: 56.9 Jack Roberts

  10. Phase Profile – Filtered, Mixer/sqrt(Diode) Calibration Jack Roberts

  11. Phase Profile – Filtered, Mixer/sqrt(Diode) Calibration Jack Roberts

  12. Phase Profile – Filtered, Mixer/sqrt(Diode) Calibration • At a first glance, very similar to the unfiltered calibration plots. Jack Roberts

  13. Resolution Comparison – Filtered vs. Unfiltered • Resolution appears to be a bit better for the filtered calibration. Jack Roberts

  14. Comparison – Unfiltered vs. Filtered M1 Jack Roberts

  15. Comparison – Unfiltered vs. Filtered M1 Jack Roberts

  16. Comparison – Unfiltered vs. Filtered M1 Jack Roberts

  17. Comparison – Unfiltered vs. Filtered M2 Jack Roberts

  18. Comparison – Unfiltered vs. Filtered M2 Jack Roberts

  19. Comparison – Unfiltered vs. Filtered M2 Jack Roberts

  20. Comparison – Unfiltered vs. Filtered M3 Jack Roberts

  21. Comparison – Unfiltered vs. Filtered M3 Jack Roberts

  22. Comparison – Unfiltered vs. Filtered M3 • There are differences in the relative scale of the reconstructed phase from the two calibrations. Jack Roberts

  23. Filtered vs. Unfiltered Calibration Constant Mean Mean • Filtered/unfiltered calibration constants divided by mean to make them comparable. • Only mean value used in phase reconstruction. • Differences vs. sample no. will cause phase shifts. Mean Jack Roberts

  24. Mean Pulse Phase Stability Jack Roberts

  25. Mean Pulse Phase Stability Jack Roberts

  26. Mean Pulse Phase Stability • Only short runs, but around 0.5o – 1.0o of jitter in the mean pulse phase. Jack Roberts

  27. Summary • The IIR filter appears to do a good job but lab tests needed to accurately determine decay constants. • Difference in relative scale of reconstructed phase for unfiltered Mixer/Diode and filtered Mixer/sqrt(Diode) calibrations. • Can look in to cross-talk between the mixer and diode. • Side notes: • Installation of kickers, rearrangement of magnets etc. in TL2 for the feedforward system in progress. • M2 can’t be repaired due to radiation. Planned to test using horizontal pickups instead of vertical. 4th monitor will be built. • May be delays in installing M3 in its final location. • Thinking about how to integrate FONT DAQ with CTF3 data. Jack Roberts

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