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Watson EMC Scanner

Watson EMC Scanner. IEEE West Michigan EMC Chapter. Introduction. Created as a senior project for GVSU sponsored by sponsored by Gentex and JCI via Jim Teune and Scott Mee Project team consisted of Xu Li, James Koehler, Schuyler Burson , Troy Forrest

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Watson EMC Scanner

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  1. Watson EMC Scanner IEEE West Michigan EMC Chapter

  2. Introduction • Created as a senior project for GVSU sponsored by sponsored by Gentex and JCI via Jim Teune and Scott Mee • Project team consisted of Xu Li, James Koehler, Schuyler Burson, Troy Forrest • Scanner is available for public use. Talk to Dr. Adamczyk • System can be benchmarked • Thanks to Mr. Don Ferris for his generous help, it’s impossible to build this scanner without him

  3. Near Field Probing • Less than 1 λ, which at 3 GHz is 10cm. • Intensity in the near field decays more rapidly with distance from the source that in the far field. • E field and H field intensity can be independent and one can be dominant.

  4. Near Field Probes • H-field • E-Field

  5. Clock 5 Radiated Emissions

  6. Probe Comparison • H-Field Probe • E-Field Probe Room for improvement: Design to consider both H and E fields

  7. H-Field Orientation Comparison • Loop is parallel to current • Loop is perpendicular to current Room for improvement: Design to consider 2 or more probe orientations (rotate)

  8. Correction Factors • Application of probe correction characteristics can be used to maintain a level frequency response.

  9. Use of near field scanning • Provides additional understanding of circumstances. • Debugging mysterious noise sources. • Its just cool

  10. Example: External Module • Radiated emissions failure caused by external device not product.

  11. Example: Component Level • 100MHz shows emissions coming from the display module

  12. Example: Gain further understanding of module operation and failure

  13. Example: Characterize software effects

  14. Components • Main Components: • Canon PowerShot SX110 IS • Asymtek xyz-positioner • Rohde & Schwarz FSL3 Spectrum Analyzer • Probes (can be different) • Computer • Others: • Pre-Amplifier • Fixtures and Clamps • Work Surface

  15. Budget

  16. Communication Between Parts

  17. Camera Technical Challenges: • Resolution: 8 inch by 8 inch image with enough resolution to distinguish individual pins on IC • Fisheye Effect: Distortion along the edges of the photograph • Parallax: Displacement or difference in the apparent position of an object • Communication: Interface with LabVIEW

  18. Fisheye Take 8"x8" image from 10" away Acceptable resolution for most components Parallax Low Resolution

  19. Canon PowerShot SX110 IS • Remote via PSRemote dll through Labview • 6.0mm - 60.0mm Focal Length • 9.0MP • $120 used camera • $95 Software

  20. Image From PowerShot SX110 Note: Fish eye and parallax can also be reduced by distancing the camera from the DUT however resolution may be reduced

  21. Asymtek xyz-positioner • RS232 Connection Interface • First In, First Out buffer containing ASCII coded commands. • Minimum Motor Step Size: 0.001 in. (0.0245 mm)

  22. Positioner Communication • "Command to send" is an input string containing the command sent to the positioner through RS232. • This example opens the port, delays 50ms, writes to the port, delays 50ms, reads the bytes from the port, and then closes the port.

  23. Definition of position [0,0] Consider center of image as [0,0] Probe is not concentric with camera. This requires an offset. Distance from [0,0] and size of selected scan area are in pixels and must be converted to distance.

  24. Pixel-distance calibration and need for height from work surface

  25. Pixel-distance calibration and need for height from work surface Room for improvement: Automated Vertical Distance Detection

  26. Rhode & Schwarz FSL3 9kHz-3MHz Ethernet communication 300Hz-10MHz resolution bandwidth 1Hz-10MHz Video bandwidth Suggested 30dB pre-amplifier Room for improvement: Included communication drivers for multiple Spectrum Analyzers

  27. Any* Near Field Probe can be Used Designed to accommodate Langer probe sets & VanDoren probe sets. Universal probe mount allows for alternate fixtures. Probe correction factors can be used if provided in proper format. Room for improvement: Design to ensure consistent vertical position of probe relative to mount

  28. Main Software - LabVIEW and Add-ons • LabVIEW 2012: GUI, Control and Data Acquisition of SA, Control of Positioner • VDM: Image Processing such as Density Color Overlay • Microsoft Office Report Generation Kits • PSRemote: Third party software for remotely controlling camera

  29. PSRemote 1. Dynamic-link library (.dll) files were converted to LabVIEW sub-VIs. 2. Communication was approved. 3. Executable file (.exe) file must be running to provide the functionality of connecting to the camera

  30. How Scanner Works • Complete System Flowchart • Subprocesses explained in detail in following sections.

  31. How Calibration Works • Calibrates motor step sizes and pixel/physical area ratio • Compares hard-coded pixel sizes and locations with physical shaded grid section.

  32. How Scanning Works • Positioner moves in snake-like pattern over selected area. • The maximum value in each reading of the spectrum analyzer is placed into an array. • "Home" is the corner of the overall work area, not the user selectable area.

  33. How Image Overlay Works 1. Obtain Scan Area Image 2. Treat Data from SA 3. Overlay Data on Image 4. Save Final Image

  34. References Langer-emv.com Dong, X., Deng, S., & Beetner, D. (n.d.). Analysis of Chip-level EMI using Near-Field Magnetic Scanning. Retrieved June 25, 2014

  35. Q&A

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