ELECTROMAGNETIC INTERFERENCE (EMI) Eric Mitchell Phil Zanotti
Kasra Dabiran Leon Voskov Ross Schwarz Slide 2 OVERVIEW
Introduction Examples Wireless Devices Natural Interferences
Switching Circuits Radio Frequency Electromagnetic warfare
Prevention and Mitigations Techniques Standards and Regulations
Summary Slide 3 BACKGROUND What is EMI? Electromagnetic
Interference is disturbance that affects an electrical circuit
Caused by induction or outside radiation Can temporary and
permanently disrupt circuit components Big design issue for new
products Slide 4 HOW DOES EMI WORK? Causes Electric fields
radiating from currents Switching circuits, clocks, natural fields,
ect. Coupling of electric fields into circuits and components
Unintentional and intentional Effects Causes problems for
electronics Loss and disruption of data Growing problem with more
advanced devices Slide 5 EXAMPLES OF EMI Slide 6 SOLAR INTERFERENCE
2012 Solar Maximum 11 year solar cycles Flight routes over north
pole changed Solar Storm of 1859 March 1989 Solar Storm X-class
solar flare Power outage in Quebec Communications with some
satellites disrupted for hours Other potential issues Spacecraft
communication Induced currents on underground piping HF radio
interference Slide 7 INTERFERENCE AT 2.4 GHZ Why use 2.4GHz? Part
of the ISM Band No license needed to design devices in this range
FCC originally designated 2.4-2.483 GHz band for microwave ovens
Devices and protocols that operate in this band Cordless telephones
Baby monitors Bluetooth Wi-Fi 802.11b and 802.11g wireless devices
(most routers) Wireless cameras and controllers Slide 8 CELLULAR
DEVICE INTERFERENCE Airplanes No proven scientific basis for
banning cell phone use on airplanes FAA, FCC, and aircraft OEMs are
unwilling to spend money to do testing Ban on cell phone use errs
on the side of caution Medical Equipment 2007 Mayo Clinic study
showed that phones have no negative effect on medical equipment FDA
has developed standards for pacemaker OEMs to ensure safety Slide 9
POWER CONVERTERS Capacitive, Inductive, and Resistive loads Caused
by sudden load changes Found in many household items Computers,
phone chargers, TVs, etc. Minimal or no EMI effect created Slide 10
ELECTROMAGNETIC PULSE Intense surge of electromagnetic radiation
Created using high-energy explosion (i.e. nuclear) Gamma rays trap
high-energy electrons in earths magnetic field Destroys all power
electronics connected to affected power grid Slide 11 RADIO
FREQUENCY INTERFERENCE Two way transmitters, radio stations,
amateur radio broadcast Interrupted signal before reaching receiver
Results in signal masking and distortion Slide 12 PREVENTION AND
MITIGATION Slide 13 EMI FILTERS AND CHOKES Coil of wire wound
around magnetic core Blocks high-frequency AC in a circuit Passive
inductor Impedance is proportional to frequency Simple and
inexpensive Energy Reflected back up the cable Absorbed resistively
within ferrite core (heat) Audio vs. Radio Slide 14 ELECTROMAGNETIC
SHIELDING ShieldsExamples Enclosure formed by conducting material
Isolates electrical devices and blocks external electric fields
Often known as Faraday Cage (invented in 1836) Amount of reduction
depends Material and its thickness Size of shielded volume
Frequency of fields Cables MRI scan room Microwave oven Electronic
devices Slide 15 MITIGATION SOFTWARE AND TECHNIQUES EMI Analyst is
a tool used for meeting EMI requirements set by regulatory agencies
Combines all four areas of EMI analysis Conducted Emissions
Radiated Emissions Conducted Susceptibility Radiated Susceptibility
Money Saving Tool Reduction of circuit design area Slide 16 FINAL
EMISSIONS SCREENSHOT Slide 17 STANDARDS AND REGULATIONS Slide 18
EMI TESTING PROCEDURE Slide 19 REGULATION COMMITTEES FCCCISPR The
International Special Committee on Radio Frequency Interference
International House hold appliances, Ignition systems, fluorescent
lamps Federal Communications Commission United States Modems,
Printers, and other I/O devices Slide 20 CLASSES OF REGULATIONS
Class AClass B A computing device that is marketed for use in a
commercial, industrial, or business environment; exclusive of a
device which is marketed for use by the general public, or which is
intended to be used in the home. A computing device that is
marketed for use in a residential environment notwithstanding use
in a commercial, business, and environmental environments. Slide 21
FCC AND CISPR CLASS A Slide 22 FCC AND CISPR CLASS B Slide 23 OTHER
TYPES OF STANDARDS MIL-STD-416DCE - Conformit Europenne Department
of Defense Even harder-to-meet standards than FCC and CISPR
Dependent on reliability of electronic and communication equipment
European Conformity Identifies that a product or machine is
compliant with all safety requirements Requirement not a voluntary
process Slide 24 CONCLUSION Introduction and Background Examples of
Electromagnetic Interference Prevention and Mitigation Techniques
Laws and Regulations Questions?
