Slide 1

IEEE West Michigan EMC ChapterWatson EMC Scanner IntroductionCreated as a senior project for GVSU sponsored by sponsored by Gentex and JCI via Jim Teune and Scott MeeProject team consisted of Xu Li, James Koehler, Schuyler Burson, Troy ForrestScanner is available for public use. Talk to Dr. AdamczykSystem can be benchmarkedThanks to Mr. Don Ferris for his generous help, its impossible to build this scanner without him

Near Field ProbingLess 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.

Near Field ProbesH-field

E-Field

Clock 5 Radiated Emissions

Probe ComparisonH-Field Probe

E-Field Probe

Room for improvement:Design to consider both H and E fieldsH-Field Orientation ComparisonLoop is parallel to current

Loop is perpendicular to current

Room for improvement:Design to consider 2 or more probe orientations (rotate)Correction FactorsApplication of probe correction characteristics can be used to maintain a level frequency response.

Use of near field scanningProvides additional understanding of circumstances.Debugging mysterious noise sources. Its just coolExample: External Module Radiated emissions failure caused by external device not product.

Example: Component Level100MHz shows emissions coming from the display module

Example: Gain further understanding of module operation and failure

Example: Characterize software effects

Components

Main Components:Canon PowerShot SX110 ISAsymtek xyz-positionerRohde & Schwarz FSL3 Spectrum AnalyzerProbes (can be different)Computer

Others:Pre-AmplifierFixtures and ClampsWork Surface

BudgetOriginal BudgetDescriptionExpected CostCamera$1000Capture Card$500Cables$250Cart Fixture Supplies$200NI Vision DeveloperN/AAsymtek PositionerDonation (Gentex)Pre-amplifierGVSUSniffer ProbesGVSUNI LabviewGVSUSpectrum AnalyzerGVSUTOTAL$2000Final CostDescriptionExpected CostCamera$120 + $95 (software)Capture CardN/ACablesN/ACart Fixture SuppliesDonation (Gentex)NI Vision DeveloperGVSUAsymtek PositionerDonation (Gentex)Work SurfaceDonation (JCI)Pre-amplifierGVSUSniffer ProbesGVSUNI LabviewGVSUSpectrum AnalyzerGVSUOther$100TOTAL$315Communication Between Parts

CameraTechnical 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 photographParallax: Displacement or difference in the apparent position of an object Communication: Interface with LabVIEWMake a good balance between expense and quality of image. Industrial camera was examined first with the given budget but sponsors try to keep budget low. so, we tried webcam and point-and-shoot camera.

ParallaxLow ResolutionFisheyeTake 8"x8" image from 10" awayAcceptable resolution for most componentsIt may be better to chop this image up and show a capacitor toward the edge to highlight fisheye and show the ic up close to show the resolutionCanon PowerShot SX110 ISRemote via PSRemote dll through Labview6.0mm - 60.0mm Focal Length9.0MP$120 used camera$95 Software

Image From PowerShot SX110

Note:Fish eye and parallax can also be reduced by distancing the camera from the DUT however resolution may be reducedAsymtek xyz-positioner

RS232 Connection Interface

First In, First Out buffer containing ASCII coded commands.

Minimum Motor Step Size: 0.001 in. (0.0245 mm)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.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.Pixel-distance calibration and need for height from work surface

Pixel-distance calibration and need for height from work surface

Room for improvement:Automated Vertical Distance DetectionRhode & Schwarz FSL3 9kHz-3MHzEthernet communication300Hz-10MHz resolution bandwidth1Hz-10MHz Video bandwidthSuggested 30dB pre-amplifier

Room for improvement:Included communication drivers for multiple Spectrum AnalyzersAny* Near Field Probe can be UsedDesigned 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 mountMain 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

VAS, video acquisition software, VDM, video development module, and Report Generation Kits are add-ons packages of LabVIEWPSRemote1. 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

How Scanner WorksComplete System Flowchart

Subprocesses explained in detail in following sections.

How Calibration WorksCalibrates motor step sizes and pixel/physical area ratioCompares hard-coded pixel sizes and locations with physical shaded grid section.

How Scanning WorksPositioner 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.

How Image Overlay Works1. Obtain Scan Area Image

2. Treat Data from SA

3. Overlay Data on Image

4. Save Final Image

Camera always take a picture for the same area (an 8-by-8 area). When user selects a want-to-test area on the picture by LabVIEW Cursors, it always returns an unique starting point in terms of the given (0, 0) location. ReferencesLanger-emv.comDong, X., Deng, S., & Beetner, D. (n.d.). Analysis of Chip-level EMI using Near-Field Magnetic Scanning. Retrieved June 25, 2014

Q&A