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GSI Dec. 05, 2012

Digital Signal Processing for BPM ( Signal Phase Detection ). Mohammed Almalki (Beam Diagnostic, GSI, Frankfurt Uni). GSI Dec. 05, 2012. Mohammed Almalki ( GSI, Frankfurt Uni) Digital Signal Processing for BPM ( Signal Phase Detection ). Purpose.

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GSI Dec. 05, 2012

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  1. Digital Signal Processing for BPM (Signal Phase Detection) Mohammed Almalki (Beam Diagnostic, GSI, Frankfurt Uni) GSI Dec. 05, 2012 • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  2. Purpose • Digital Signal Processing for BPM (Signal phase detection) Why ? Reason How ? Method • Experimental Test • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  3. Signal Phase Detection (TOF) -General idea- (Motivations) • Libera Singlepass H Experimental Test (March 2012) 1 3 Libera Phase Detection Algorithm (Down Conversion and IQ Demodulation) • Libera Singlepass H Experimental Test (Nov 2012) • Conclusion (General Remarks) 2 4 5 Outline • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  4. Signal Phase Detection (TOF) -General idea- (Motivations) • Libera Singlepass H Experimental Test (March 2012) 1 3 Libera Phase Detection Algorithm (Down Conversion and IQ Demodulation) • Libera Singlepass H Experimental Test (Nov 2012) • Conclusion (General Remarks) 2 4 5 Outline • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  5. General idea (Motivation) 1 W.Kaufmann, presentation 19.04.2012 Signal Phase Detection, what for ! Time-of-flight → Beam velocity → Beam Energy , L PU2 PU1 Accelerator ∆t • Different bunch shape leads to different signal form. • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  6. Signal Phase Detection (TOF) 2 PU1 PU2 Accelerator Time-domain processing PU signals • N : number of bunches Lecture Notes, JAUS, P. Forck • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  7. Signal Phase Detection (TOF) 2 PU1 PU2 Accelerator Frequency-domain processing PU2 signals PU1 signal RF Libera SinglePass H Reference signal (325 MHz) Libera SinglePass H : processes two signals digitally and calculates phase difference in respect to a master signal (RF accelerating signal). How ? Using digital down conversion technique and IQ demodulation. • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  8. Libera Phase Detection Algorithm 1 Consepts in DSP (Digital Signal Processing) 2 Digital Down Conversion (IQ Modulation) 3 IQ Demodulation (Phase detection) 4 Phase Detection for BPM (P-LINAC) • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  9. 1 Consepts in DSP (Digital Signal Processing) 2 Digital Down Conversion (IQ Modulation) 3 IQ Demodulation (Phase detection) 4 Phase Detection for BPM (P-LINAC) • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  10. Consepts in Digital Signal Processing 1 1- Sampling theorem (A/D converter ). 2- Nyquist criterion (Aliasing). 3- Modulation (Mixer), Frequency Translation Digital Down Conversion IQ sampling (Modulation) IQ Demodulation • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  11. Consepts in Digital Signal Processing 1 2- Nyquist criterion (Aliasing). 1- Sampling theorem (A/D converter ) Sampling freq. A/D converter • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  12. Consepts in Digital Signal Processing 1 Digital Down Conversion (Undersampling) 3- Modulation (Mixer) filtering • IF Down-conversion • y(t) • z(t) • x(t) Lower sideband Upper sideband Frequency Translation A/D converter is a form of modulation • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  13. The carrier signal Case 1 • The modulating signal • The modulation – multiplication – is: • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  14. The carrier signal Case 2 • The modulating signal • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  15. 1 Consepts in DSP (Digital Signal Processing) 2 Digital Down Conversion (IQ Modulation) 3 IQ Demodulation (Phase detection) 4 Phase Detection for BPM (P-LINAC) • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  16. Digital Down Conversion (IQ Modulation) 2 IQ Signal Representation • The signal can be represented in either Cartesian or in polar coordinates . • “IQ” come from the polar representation (amplitude/phase). Q The in-phase component Q I I The quadrature-phase component. RF application in DSP, T. Tschilcher, CAS 2007 (amplitude/phase) I & Q Contain all information about the signal. • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  17. Digital Down Conversion (IQ Modulation) 2 • It is possible to extract IQ information based on the sampled data stream. • The goal of IQ sampling is to be able, then, to extract its amplitude/phase or IQ information. Understanding digital signal processing, R. Lyons • if the IQ sampling achieved where : • if the IQ sampling achieved where : I The phase advance between two samples = 90ͦ I Q I I Q Q Q • It is possible to choose the fs such that it is a multiple of the signal frequency: amplitude -Q -Q -Q -Q -I -I -I -I Time (s) • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  18. 1 Consepts in DSP (Digital Signal Processing) 2 Digital Down Conversion (IQ Modulation) 3 IQ Demodulation (Phase detection) 4 Phase Detection for BPM (P-LINAC) • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  19. IQ Demodulation (Phase detection) 3 RF application in DSP, T. Tschilcher CAS 2007 • The goal is to extract I and Q again . I LPF Q LPF NCO Filter out • Multiply digital waveform by complex “local oscillator” Filter out • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  20. 1 Consepts in DSP (Digital Signal Processing) 2 Digital Down Conversion (IQ Modulation) 3 IQ Demodulation (Phase detection) 4 Phase Detection for BPM (P-LINAC) • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  21. Phase Detection for BPM (P-LINAC) 4 from PUs Amp. I IF (29.4 MHz) LPF Att. Sampled at 117 MHz BPF Q LPF ADC NCO Libera H Ref. 325MHz • Four inputs and one reference signal. • All signals are processed by an analoge front-end (band-width filter, amplifier and some attenuatior) and down sampled with at 117 MHz → the signal are converted to IF ( digital mixing). • I/Q Demodulation, to extract amplitude/phase. • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  22. To remind PU Accelerator PU signal Libera IQ Modulation (Sampling) Digital Down Conversion IQ Demodulation Filtering pre-amplification I & Q Amp Phase • Analogue front end filtered • Down-sampled (mixing) • Modulation (× sin & cos) Amp Phase • Analogue front end filtered • Down-sampled (mixing) • Modulation (× sin & cos) I & Q RF signal reference • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  23. Signal Phase Detection (TOF) -General idea- (Motivations) Libera Singlepass H Experimental Test (March 2012) 1 3 Libera Phase Detection Algorithm (Down Conversion and IQ Demodulation) Libera Singlepass H Experimental Test (Nov 2012) Conclusion (General Remarks) 2 4 5 Outline • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  24. Libera Singlepass H Experimental Test (March 2012) • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  25. Libera Singlepass H, Experimental Test 1 The purpose : • 1- Investigating Libera capability to measure the phase with acceptable precision • as bunch shape is varying and how signal amplitude effects the phase reading. • 2- Comparing with time domain measurements (from a fast Oscilloscope) and FFT calculations Method : 1- A single BPM is used to act as a "Bunch arrival monitor". 2- Different bunches are generated (with different amplitudes) and Libera measures directly the signal’s phase. A similar measurements are performed using Oscilloscope (for comparison). • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  26. 1 Experimental Setup (Beam line schematic). Data Tratment (Data from the Libera H & the Scope) 2 Examples 3 4 Phase Measurements Results (Time & frequency domain) 5 Conclusion (1) • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  27. 1 Experimental Setup (Beam line schematic). Data Tratment (Data from the Libera H & the Scope) 2 Examples 3 4 • Phase Measurements Results (Time & frequency domain) 5 Conclusion (1) • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  28. Experimental Setup (Beam line schematic). 1 • Beam The Macropulse structure • UN6 W1T • UN6 DK1 • UN6 BB14 • UN6 MU3 • UN6 QD7 • UN6 DK4 • BPM • UN6 DK2 • UN6 DP2 • UN6BB14 : Buncher for bunch gymnastics longitudinally • UN6QD7 : Quadrupole doublet for beam focussing • UN7MU3: Dipole for position variation horizontally • BPM : Capacitive pickup with for electrodes • UN7DG2 (within box UN7DK2): Current grid for position measurements • UN7DP2: Capacitive pickup with single electrode • UN7DT1: Current transformer • UN6 DR2 • UN6 MU4 • UN6 DT1 • UN6 DK3 • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  29. 1 Experimental Setup (Beam line schematic). Data Tratment (Data from the Libera H & the Scope) 2 Examples 3 4 Phase Measurements Results (Time & frequency domain) 5 Conclusion (1) • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  30. Data Tratment 2 What kind of data we got & how it can be used ? 22 Bunche shapes • from the scope (Time domain) • from Libera (Frequency domain) • Bunch shapes • Bunch Position • Signal Phase 500 Mv/div Voltages readout from PUs plates Phase 2 ns/div • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  31. Data from the Libera H • Bunch Position y(mm) • The " Libera Single Pass H" provides the measured phase calculated in respect to a master oscillator – RF accelerating frequency. • PUs voltages (V) 0.5 0 - 0.5 -1 • The amplitude is given in steps of 1 μs (correspond to 108 bunches) for a train of 129 μs. Every data set corresponds to 1 macropulse. • Diff/Sum (%) -1 0 1 2 X(mm) Libera phase (deg.) 129 μs of Aquisition • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  32. Data from the scope A second system was used where the signal of the pick-up was taken at a 5 GSa/s scope. • In time-domain • Amplitude (V) • Bunch structure and zero crossing determination 500 Mv/div • Amplitude (V) Time (ns) • The signal is interpolated (spline interpolation). To remaind, Why we do all this ? To study the coorelation between different techniqes for the phase measurements phase from Libera H, phase in time domain measurements and and FFT calculations • Amplitude (V) 2 ns/div • In frequency-domain Phase from Libera H, Phase from in time domain, Phase from FFT calculations Frequency (GHz) • Extracting window for only one bunch further calculations for FFT calculation. Time (μ s) • Phase (deg.) • Amplitude (V) Time (μs) • Amplitude and phase spectrum Frequency (GHz) Time (μs) Time (ns) • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  33. 1 Experimental Setup (Beam line schematic). Data Tratment (Data from the Libera H & the Scope) 2 Examples 3 4 Phase Measurements Results (Time & frequency domain) 5 Conclusion (1) • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  34. Examples 3 Bunch 3 (reference) y(mm) • PUs voltages (V) Libera phase (deg.) • Amplitude (V) • Diff/Sum (%) • Bunch Position Time (μs) 129 μs of Aquisition 129 μs of Aquisition X(mm) • Amplitude (V) • Amplitude (V) • Amplitude Frequency (GHz) Time (ns) Time (μs) • Amplitude (V) • Amplitude (V) • Phase (deg.) Frequency (GHz) Time (ns) Time (μs) • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  35. Examples 3 Bunch 1 6.5 ͦ • Amplitude ∆t = 102.33 ps = 12 ͦ Libera phase (deg.) • Amplitude (V) Frequency (GHz) 109.73ͦ 99.13ͦ 4 ns • Phase (deg.) 360 ͦ = 3.07 ns ∆φ = 10.6 ͦ Time (μs) Frequency (GHz) 129 μs of Aquisition Libera single pass H Time domain processing FFT calculations • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  36. Examples 3 Bunch 10 18.3 ͦ • Amplitude ∆t = 73.36 ps = 8.6 ͦ Libera phase (deg.) • Amplitude (V) Frequency (GHz) 102.99 ͦ 99.13ͦ 4 ns • Phase (deg.) 360 ͦ = 3.07 ns ∆φ = 3.8 ͦ Time (μs) Frequency (GHz) 129 μs of Aquisition Bunch 20 -147.4 ͦ • Amplitude ∆t = 57.3 ps = 6.7 ͦ Libera phase (deg.) • Amplitude (V) Frequency (GHz) -78.62 ͦ ͦ 99.13ͦ 4 ns • Phase (deg.) ∆φ = 177.7 ͦ 360 ͦ = 3.07 ns Time (μs) Frequency (GHz) 129 μs of Aquisition • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  37. 1 Experimental Setup (Beam line schematic). Data Tratment (Data from the Libera H & the Scope) 2 Examples 3 4 Phase Measurements Results (Time & frequency domain) 5 Conclusion (1) • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  38. Phase Measurements Results 4 Time-domain & frequency domain. Time-domain FFT calculations Libera Single pass H 500 Mv/div 2 ns/div From the Oscilloscope From Libera Single pass H • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  39. Phases from Libera H, phase from the scope & phase calculations (looking for a correlation) (Libera H, FFT calculations) Phase Deg. Phase readout from Libera H, Deg. Zc – Zc (3) Deg. Zc – Zc (3) Deg. In the range (0.9 – 1.5 V) a correlation of the Libera phase reading and the time domain measurements by the oscilloscope is visible. • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  40. Bunch Position Calculations • Some shapes have an offset from the center. • The standard deviation increases steadily to hit a factor of 12 for the amplitude measured during the experiment (0.33 → 1.54 V). X,Y = .1*Diff(x,y)/Sum(x,y)*100 (mm) Amplitude (V) • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  41. 1 Experimental Setup (Beam line schematic). Data Tratment (Data from the Libera H & the Scope) 2 Examples 3 4 • Phase Measurements Results (Time & frequency domain) 5 Conclusion (1) • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  42. Conclusion (1) 4 1 • The bunch amplitudes : higher then 0.9 V. An agreement is observed between Libera, time domain and calculation visible, but a linear function can not be fitted to data with the anticipated accuracy. 2 • The bunch amplitudes : less then 0.9 V. The time domain processing leads to a different arrival time compared to the phase measured by Libera. • Bunch shape. 3 The applied bunch shape changes reduce not only input signal peak voltage, but also the frequency content drastically changes • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  43. The Second Test Libera Singlepass H Experimental Test (Nov 2012) • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  44. 1 The Old Unit and the New Unit differences (modifications). Performance test (Comparison btween the Old Unit and the New Unit) 2 3 Phase Measurements Results (Seven Bunch Shapes) Example 4 5 Conclusion (General Remarks) • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  45. 1 The Old Unit and the New Unit differences (modifications). Performance test (Comparison btween the Old Unit and the New Unit) 2 3 Phase Measurements Results (Seven Bunch Shapes) Example 4 5 Conclusion (General Remarks) • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  46. The Old Unit and the New Unit Differences (Modifications). 1 RF analogue front-end 1- filtering. The analogue filter is set to cover filter the 1st (108.4 MHz ) and 2nd (216.8 MHz) harmonics. So, the 1st & 2nd harmonics are processed 2- Amplifire. 3- ADC full scal. The old unit is -11 dB (3 Vpp), the new unit is -5 dB (355 mVpp). • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  47. 1 The Old Unit and the New Unit differences (modifications). Performance test (Comparison btween the Old Unit and the New Unit) 2 3 Phase Measurements Results (Seven Bunch Shapes) Example 4 5 Conclusion (General Remarks) • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  48. Performance test (Comparison btween the Old Unit and the New Unit) 2 Tha aim : to test the old and the new unit performance with different shapes and amplitudes 5 ns 5 ns 5 ns 1 ns 1 ns 1 ns Three different bunches are formed and their phases have been measured using the old and the new Libera H units at different amplitudes. • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  49. 1 The Old Unit and the New Unit differences (modifications). Performance test (Comparison btween the Old Unit and the New Unit) 2 3 Phase Measurements Results (Seven Bunch Shapes) Example 4 5 Conclusion (General Remarks) • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

  50. Phase Measurements Results (Seven Bunch Shapes) 3 Amplitude (V) 2 ns Time (μs) Seven different bunches are formed at three amplitude levels 44, 32 and 20 dB . Libera H measured the phase. The phase are then calculated using FFT for one bunch and for stream of bunches. The time domain phase are determined from zero crossing time differences. • Mohammed Almalki (GSI, Frankfurt Uni) Digital Signal Processing for BPM (Signal Phase Detection)

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