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Apr 06, 2024 176 likes •322 views

Stability Analysis of an Adaptive Notch Filter for RF Noise Suppression Trevor Vannoy APS Accelerator Systems Division Mentor: Tim Berenc Background 360 Hz 120 Hz 60 Hz 2 Reduced by ~ 30 dB Advanced Photon Source, Argonne National

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SLIDE 1

Stability Analysis of an Adaptive Notch Filter for RF Noise Suppression

Trevor Vannoy APS Accelerator Systems Division Mentor: Tim Berenc

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SLIDE 2

Background

Advanced Photon Source, Argonne National Laboratory 2

Reduced by ~30 dB 60 Hz 120 Hz 360 Hz

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SLIDE 3

Adaptive Noise Canceller

Advanced Photon Source, Argonne National Laboratory 3

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SLIDE 4

Adaptive Noise Canceller

Advanced Photon Source, Argonne National Laboratory 4

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SLIDE 5

Closed Loop Transfer Function

Advanced Photon Source, Argonne National Laboratory 5

Open-Loop transfer function Closed-Loop transfer function

  • Stability of the closed-loop system is determined from its poles
  • Its poles are the zeros of 1 + G(s)
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SLIDE 6

Advanced Photon Source, Argonne National Laboratory 6

Argument Principle

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SLIDE 7

Nyquist Example

Advanced Photon Source, Argonne National Laboratory 7

ϒ Γ

  • Can handle poles on the contour by integrating around them
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SLIDE 8

Adaptive Notch Filter

Advanced Photon Source, Argonne National Laboratory 8

G(z)

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SLIDE 9

Adaptive Notch Filter Actual Implementation

Advanced Photon Source, Argonne National Laboratory 9

G(z)

BPF LPF Gains

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SLIDE 10

Advanced Photon Source, Argonne National Laboratory

Labview Code

10

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SLIDE 11

Lab Setup

Advanced Photon Source, Argonne National Laboratory 11

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SLIDE 12

Results

Advanced Photon Source, Argonne National Laboratory 12

magnitude phase Nyquist Non-ideal Hilbert filter Improved Hilbert filter

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SLIDE 13

Results

Advanced Photon Source, Argonne National Laboratory 13

magnitude phase Higher gain Adding 3 samples of group delay to theoretical model

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SLIDE 14

Future Work

  • Determine where additional group delay is coming from
  • Determine where -1.2 dB gain difference is coming from
  • Improve Hilbert filter for other frequency channels

– Add multiplier to fix scaling – Redesign Hilbert filter

  • Model 120 Hz and 360 Hz channels

– Change parameters in Mathematica code

  • Include existing RF feedback loops in analysis

Advanced Photon Source, Argonne National Laboratory 14