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IEEE West Michigan EMC Chapter Watson EMC Scanner

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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, its impossible to build this scanner without him

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Near Field Probing Less than 1 , 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.

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Near Field Probes H-field E-Field

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Clock 5 Radiated Emissions

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

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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)

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

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

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

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

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Example: Gain further understanding of module operation and failure

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Example: Characterize software effects

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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

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Budget Original Budget DescriptionExpected Cost Camera$1000 Capture Card$500 Cables$250 Cart Fixture Supplies$200 NI Vision DeveloperN/A Asymtek PositionerDonation (Gentex) Pre-amplifierGVSU Sniffer ProbesGVSU NI LabviewGVSU Spectrum AnalyzerGVSU TOTAL$2000 Final Cost DescriptionExpected Cost Camera$120 + $95 (software) Capture CardN/A CablesN/A Cart Fixture SuppliesDonation (Gentex) NI Vision DeveloperGVSU Asymtek PositionerDonation (Gentex) Work SurfaceDonation (JCI) Pre-amplifierGVSU Sniffer ProbesGVSU NI LabviewGVSU Spectrum AnalyzerGVSU Other$100 TOTAL$315

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Communication Between Parts

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

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

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

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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

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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)

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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.

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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.

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Pixel-distance calibration and need for height from work surface

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Room for improvement: Automated Vertical Distance Detection

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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

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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

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

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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

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

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

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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.

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

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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

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Q&A