This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Slide 1
IEEE West Michigan EMC Chapter Watson EMC Scanner
Slide 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, its impossible to build this scanner without him
Slide 3
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.
Slide 4
Near Field Probes H-field E-Field
Slide 5
Clock 5 Radiated Emissions
Slide 6
Probe Comparison H-Field Probe E-Field Probe Room for
improvement: Design to consider both H and E fields
Slide 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)
Slide 8
Correction Factors Application of probe correction
characteristics can be used to maintain a level frequency
response.
Slide 9
Use of near field scanning Provides additional understanding of
circumstances. Debugging mysterious noise sources. Its just
cool
Slide 10
Example: External Module Radiated emissions failure caused by
external device not product.
Slide 11
Example: Component Level 100MHz shows emissions coming from the
display module
Slide 12
Example: Gain further understanding of module operation and
failure
Slide 13
Example: Characterize software effects
Slide 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
Slide 15
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
Slide 16
Communication Between Parts
Slide 17
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
Slide 18
Parallax Low Resolution Fisheye Take 8"x8" image from 10" away
Acceptable resolution for most components
Slide 19
Canon PowerShot SX110 IS Remote via PSRemote dll through
Labview 6.0mm - 60.0mm Focal Length 9.0MP $120 used camera $95
Software
Slide 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
Slide 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)
Slide 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.
Slide 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.
Slide 24
Pixel-distance calibration and need for height from work
surface
Slide 25
Room for improvement: Automated Vertical Distance
Detection
Slide 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
Slide 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
Slide 28
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
Slide 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
Slide 30
How Scanner Works Complete System Flowchart Subprocesses
explained in detail in following sections.
Slide 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.
Slide 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.
Slide 33
How Image Overlay Works 1. Obtain Scan Area Image 2. Treat Data
from SA 3. Overlay Data on Image 4. Save Final Image
Slide 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