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Electromagnetic Interference (EMI)

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Presentation on theme: "Electromagnetic Interference (EMI)"— Presentation transcript:

1 Electromagnetic Interference (EMI)
Eric Mitchell Phil Zanotti Kasra Dabiran Leon Voskov Ross Schwarz

2 Overview Introduction Examples Prevention and Mitigations Techniques
Wireless Devices Natural Interferences Switching Circuits Radio Frequency Electromagnetic warfare Prevention and Mitigations Techniques Standards and Regulations Summary

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

4 How does EMI work? Causes Effects
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

5 Examples of EMI

6 Solar Interference 2012 Solar Maximum Solar Storm of 1859
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

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 GHz band for microwave ovens Devices and protocols that operate in this band Cordless telephones Baby monitors Bluetooth Wi-Fi b and g wireless devices (most routers) Wireless cameras and controllers

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

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

10 Electromagnetic Pulse
Intense surge of electromagnetic radiation Created using high-energy explosion (i.e. nuclear) Gamma rays trap high-energy electrons in earth’s magnetic field Destroys all power electronics connected to affected power grid

11 Radio Frequency Interference
Two way transmitters, radio stations, amateur radio broadcast Interrupted signal before reaching receiver Results in signal masking and distortion

12 Prevention and Mitigation

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

14 Electromagnetic Shielding
Shields Examples 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

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

16 Final Emissions Screenshot

17 Standards and Regulations

18 EMI Testing Procedure

19 Regulation Committees
FCC CISPR Federal Communications Commission United States Modems, Printers, and other I/O devices The International Special Committee on Radio Frequency Interference International House hold appliances, Ignition systems, fluorescent lamps

20 Classes of Regulations
Class A Class 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.”

21 FCC and CISPR Class A

22 FCC and CISPR Class B

23 Other types of standards
MIL-STD-416D CE - Conformité Européenne 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

24 Conclusion Introduction and Background
Examples of Electromagnetic Interference Prevention and Mitigation Techniques Laws and Regulations Questions?

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