EMC Back to Basics 2014 - · PDF fileCISPR 22 - Information ... • What is CISPR 16-1-1? Specifies the characteristics and performance of equipment for the measurement of radio disturbance

EMC Back to Basics

Matthew Carter

EMC Product Support Engineer

Agilent Technologies Inc.

April 16, 2014

© Agilent Technologies, Inc. 2014

Agenda – EMC Back to Basics

• Overview

• What is Electromagnetic Compatibility?

• Which equipment?

• Pre-compliance vs. Compliance

• Which standards?

• EMI Receiver Architecture

• Specifications: Which are important and why?

• Making an Emissions Measurement

• Other equipment considerations

• Q&A

EMC Back to Basics 2014

4

Sources of Electromagnetic Interference

•Natural Sources

-Lightning

-Sun Spots

•Unintentional emitting products

-Power lines

-Motors (mixers, hair dryers etc)

-Lighting, appliances

•Devices that intentionally emit signals

-Most computers

-Hand held communication devices

-Radar, transceivers, broadcast equipment etc


5


6

Basic Definitions

Electromagnetic Compatibility (EMC):

The ability for electrical devices to operating in the same environment

without interfering with one another

Electromagnetic Interference (EMI):

Electromagnetic energy emissions from one device causing reduced or

degraded performance in another device

Electromagnetic Compliance

A product is considered to be in Electromagnetic Compliance when it

meets all applicable electromagnetic regulations.


7

EMC Market Overview

Global market, mandatory regulation

− Vendors test in order to be able to sell their products – Electronic “Smog testing”

Commercial Standards determined by International Committee

− Slow moving, political

Adaptive

− Adapt techniques and measurements

to meet the needs of rapidly changing products – Eg: IT, Cellular, Wireless, Multimedia


8

EMC Market Segmentation

Emissions Radiated & Conducted - Compliance

- Pre-Compliance

Immunity Radiated & Conducted

Compliance

Measurement

Type:

Commercial Military Application:

- Product Type

- Product Class

- Country - .

Sub-segments:

Definitions: Emissions, Susceptibility, Immunity

Radiated

Emissions

Conducted

Emissions

Conducted

Susceptibility

(or Immunity)

Radiated

Susceptibility

(or Immunity)


Measurement Equipment – Emissions

EUT EUT Mains

tran

sd

ucer

Radiated

Emissions

Compliance receivers

Spectrum Analyzers

Preamps

Antennas

Measurement SW

Towers

Turntables

Control SW

Open Sites

Anechoic Chambers

Semi-Anechoic Chambers

TEM cells

Reverberation chambers

Artificial Mains Networks

LISN - (line impedance stabilization network)

Conducted Transducers

Measurement SW

Equipment

Conducted

Emissions


http://www.home.agilent.com/agilent/product.jspx?cc=US&lc=eng&nid=-33932.710350&imageindex=1

http://www.home.agilent.com/agilent/product.jspx?cc=US&lc=eng&nid=-33932.710350&imageindex=1

Compliance vs. Precompliance Measurements

Precompliance Measurements

- “Unofficial” performance estimate done prior

to Full Compliance test

- Typically done with SA on available location

- Purpose is to minimize chance of failure at

Compliance test.

Full Compliance

- Pass/Fail final regulatory testing

- Requires specific equipment and test site - must comply to specific Mil or Comm’l standards

- Expensive and time consuming

MXE

X-Series w/

N6141A


Measurement Equipment – Immunity

EUT EUT AMN

tran

sd

ucer

Radiated

Immunity

Equipment

Conducted

Immunity

~

~

transducer

ES

D s

ourc

e

Screen rooms

TEM cells

GTEM cells

RF Sources

Power meters

Power amps

Antennas

Measurement SW

Control SW

LISN

Coupling Transducers

- clamps, etc.

ESD sources


http://www.google.com/products/catalog?q=agilent+RF+signal+generator&hl=en&rls=com.microsoft:en-us:IE-SearchBox&rlz=1I7GGLL_en&prmd=ivns&resnum=5&biw=1189&bih=699&wrapid=tlif129592773554510&um=1&ie=UTF-8&cid=10741540935148215140&sa=X&ei=wEk-TdfiMYissAPJiOXDAg&ved=0CHIQ8gIwBg

http://www.google.com/products/catalog?q=agilent+RF+signal+generator&hl=en&rls=com.microsoft:en-us:IE-SearchBox&rlz=1I7GGLL_en&prmd=ivns&resnum=5&biw=1189&bih=699&wrapid=tlif129592773554510&um=1&ie=UTF-8&cid=10741540935148215140&sa=X&ei=wEk-TdfiMYissAPJiOXDAg&ved=0CHIQ8gIwBg

Segmentation


- Pre-Compliance


Compliance

Measurement

Type:


- Product Type

- Product Class

- Country - .

Sub-segments:


CISPR Recommends Commercial Limits,

Measuring Equipment and Methodologies

CISPR (Special International Committee on Radio Interference)

• a sub committee of the IEC (International Electrotechnical Commission)

• determines and recommends required emissions and immunity:

- limits for products sold in the worldwide commercial

market

- test equipment requirements

- test procedures/methodologies


CISPR Product Groups

CISPR 11 - Industrial, Scientific, and Medical (ISM) Radio-Frequency Equipment

CISPR 12 - Vehicles, Motorboats, and Spark-Ignited Engine-Driven Devices

CISPR 13 - Sound and Television Broadcast Receivers and Associated Equipment

CISPR 14 - Household Appliances, Electric Tools, and Similar Apparatus

CISPR 15 - Electrical Lighting and Similar Equipment.

CISPR 17 - Suppression Characteristics of Passive Radio Interference Filters and

Suppression Components.

CISPR 18 - Overhead Power Lines and High-Voltage Equipment

CISPR 20 - Sound and Television Broadcast Receivers and Associated Equipment

CISPR 21 - Interference to Mobile Radio communications

CISPR 22 - Information Technology Equipment–Radio Disturbance Characteristics

CISPR 24 - Information Technology Equipment–Immunity Characteristics

CISPR 25 - Receivers Used on Board Vehicles, Boats, and on

CISPR 32 – Multimedia devices emission testing (under development)

CISPR 35 – Multimedia devices immunity testing (under development)


Commercial requirements for EMI receivers

• What is CISPR 16-1-1 ?

Specifies the characteristics and performance of equipment

for the measurement of radio disturbance in the frequency

range 9 kHz to 18 GHz for commercial devices.

• CISPR 16 Equipment Requirements

• Detectors (Peak, Quasi-peak, EMI-avg, etc)

• Reference BW (aka. RBW filter)

• Amplitude Accuracy

• Input Impedance

• Ability to pass the CISPR pulse test

• And more…


IEC/CISPR Measurement Std. – CISPR 16

Equipment Std. – CISPR 16

Product Std. - CISPR 11-15, etc.

IEC 61XXX

GB

ANSI

FCC

CENELEC

EN

VCCI

Commercial Regulations


http://www.google.com/imgres?imgurl=http://www.worldmapnow.com/images/2009/11/japan-map.gif&imgrefurl=http://www.worldmapnow.com/tag/map-of-japan&h=750&w=602&sz=69&tbnid=8S7AJt7yilZkrM:&tbnh=141&tbnw=113&prev=/images?q=japan+map&zoom=1&q=japan+map&usg=__H3mldlgF2IXFqz9VOGKPFbKq-B0=&sa=X&ei=GSY-TYvhG4ugsQPm_elG&ved=0CCIQ9QEwBQ


http://www.worldmapnow.com/images/2009/11/Japan_map1.jpg

http://www.worldmapnow.com/images/2009/11/map.GIF

Commercial EMC Standards - Examples

Country

/Organization Entity Standards

US FCC, DoD FCC Part xx, MIL-STD. xxx

IEC CISPR CISPR Pub. xx

IEC TC77 IEC 6xxxx

EC CENELEC EN 550xx

Canada CSA ICES xxx

Australia/NZ AS/NZS AS/NZS CISPR xx

Japan VCCI J550xx

China (Mainland)

CCC, MoD GB xxxx- xxxx

GJB xxx- xx (equivalent to Mil-STD)

Korea MIC Equivalent to EN 550xx

Taiwan BSMI CNS xxxx


http://www.google.com/imgres?imgurl=http://www.technicalscribe.net/resources/fcc.gif&imgrefurl=http://www.technicalscribe.net/resources/&h=221&w=219&sz=3&tbnid=jC_mtIYWL8zCQM:&tbnh=107&tbnw=106&prev=/search?q=fcc+symbol&tbm=isch&tbo=u&zoom=1&q=fcc+symbol&hl=en&usg=__vAvCXXqW6J_cElGQSBIs3EGATHA=&sa=X&ei=pcglToamOof-mAXazo2HCg&ved=0CDkQ9QEwBQ

http://www.freelogovector.com/gallery/c/CSA logo.jpg

http://www.google.com/imgres?imgurl=http://www.acma.gov.au/webwr/telcomm/stds/compliance_marks/c-tick01.jpg&imgrefurl=http://www.acma.gov.au/scripts/nc.dll?WEB/STANDARD/1001/pc=PC_2796&h=100&w=100&sz=5&tbnid=Rvjty5nx_-rMKM:&tbnh=82&tbnw=82&prev=/search?q=c+tick+mark&tbm=isch&tbo=u&zoom=1&q=c+tick+mark&hl=en&usg=__HTiD_0DnCP_H-cnEh6_u7Sd8mqg=&sa=X&ei=pOwlToSBEpHyrQe_heyZCQ&ved=0CDMQ9QEwBA

http://www.google.com/imgres?imgurl=http://www.notecheckers.com/userimages/Ce-logo.jpg&imgrefurl=http://www.notecheckers.com/page2.htm&h=350&w=500&sz=20&tbnid=4McGIzj9blqxQM:&tbnh=91&tbnw=130&prev=/search?q=ce+symbol&tbm=isch&tbo=u&zoom=1&q=ce+symbol&hl=en&usg=__-WRtjehnwdbyoJUQtatA3zPHUs4=&sa=X&ei=CsolTu3lGInumAW3oMn7CQ&ved=0CC8Q9QEwBQ

Segmentation


- Pre-Compliance


Compliance

Measurement

Type:


- Product Type

- Product Class

- Country - .

Sub-segments:


Country-Specific Military Regulations

Tend to be based on

US MIL STD 461….. Current version: 461F (2007)

… but many include unique

emissions and immunity tests




MIL-STD 461 Receiver Requirements

• U.S. military standard

• Published by the Department of Defense

• MIL-STD-461 Section 4.3.10

• Receiver Requirements

• Peak detector

• Sensitivity

• Amplitude accuracy

• Frequency accuracy

• Specified dwell times



• Overview





• Q&A


22

EMI Receiver Block Diagram

23

Input 1

Input 2

Attenuation

Transient

Limiter

RF Preselector

Analog IF

Filter

Pre-amp

ADC

Digital IF

Filter

Digital Log Amp

Digital Detectors

FFT

Swept vs . FFT


MXE


24

RF Preselector Bands

RF Pre-selection (RF input filtering) Purpose of RF pre-selection

• Help to prevent overload by reducing total energy at input mixer

• RF preselector tracks the center frequency of the EMI receiver

• The bandwidth of the RF preselector is wider than the widest RBW used

Useful in measuring broadband signals

Types of filters used in RF pre-selectors

• Low-pass, Band-pass and High-pass

• Fixed and Tracking


25

Broadband

signals

Narrow

band

signals

RF Preselector

EMI Receiver Block Diagram

26

Input 1

Input 2

Attenuation

Transient

Limiter

RF Preselector

Analog IF

Filter

Pre-amp

ADC

Digital IF

Filter

Digital Log Amp

Digital Detectors

FFT

Swept vs . FFT


MXE

Methods to EMI Scanning

• Stepped Scan

• Slowest method

• LO moves for every bin

• Must re-tune LO each time

• Swept Scan

• Slow (slightly faster than Stepped)

• LO re-tunes once each sweep

• Time Domain Scan (TDS)

• Very fast

• Highly overlapped FFT (>90%)

• Alternate scan method allowed by CISPR 16


27

FFT

How Time Domain Sweep Saves Time

frequency

am

plit

ude

frequency

am

plit

ude

Receiver

FFT BW

Receiver

Resolution BW

Swept or Stepped

Frequency Scan Time Domain

Frequency Scan

28

Have to dwell at

each RBW

Only have to dwell for each

FFT BW (multiple RBWs)


28


• Overview





• Q&A


29

30

Specifications? A Definition

Specifications describe the performance of parameters covered by the product

warranty (temperature = 5 to 55°C, unless otherwise noted).

Typical values describe additional product performance information that is not

covered by the product warranty. It is performance beyond specification that 80

% of the units exhibit with a 95 % confidence level over the temperature range

20 to 30° C. Typical performance does not include measurement uncertainty.

Nominal values indicate expected performance, or describe product

performance that is useful in the application of the product, but is not covered by

the product warranty.


30

31

Key Specifications for EMI

• Sensitivity

• Amplitude Accuracy

• Scan Speed

• Others?

31


Signal

Equals

Noise

Sensitivity is the Smallest Signal That Can Be

Measured

2.2 dB


36

Specifications: Sensitivity/DANL

10 dB

Attenuation = 10 dB Attenuation = 20 dB

signal level

Effective Level of Displayed Noise is a Function

of RF Input Attenuation

Signal To Noise Ratio Decreases as

RF Input Attenuation is Increased


37

Specifications: Sensitivity/DANL

Decreased BW = Decreased Noise

100 kHz RBW

10 kHz RBW

1 kHz RBW

10 dB

10 dB

Displayed Noise is a Function of IF Filter

Bandwidth


38

Sensitivity/DANL: IF Filter (RBW)

Sensitivity/DANL: Summary

Narrowest Resolution BW allowed

Minimum RF Input Attenuation

Sufficient Averaging (video or trace - if allowed)

Using the Preamp also improves sensitivity

Noise Floor Extension

For Best Sensitivity Use:


41

Specifications: Amplitude Accuracy

Components which contribute to uncertainty are:

• Input mismatch (VSWR)

• RF Input attenuator (Atten. switching uncertainty)

• Mixer and input filter (frequency response)

• IF gain/attenuation (reference level accuracy)

• RBW filters (RBW switching uncertainty)

• Log amp (display scale fidelity)

• Calibrator (amplitude accuracy)


25

FFT

Digital IF Improves Amplitude Accuracy

Input

Connector

Down-

conversion

IF

Gain

IF

Filter

Log

Amp Video

Filter

RF Input

Attenuator 2 dB Steps Pre-selector

Log ADC

ADC DSP

• Input connector (mismatch)

• Calibrator

• RF input attenuator

− flatness and switching

• Mixer and input filter

− frequency response

Digital IF improves Amplitude Accuracy:

• Ref Level switching uncertainty (IF gain)

− Level correction digitally synthesized

• RBW filter switching uncertainty

− RBWs all digitally synthesized

• Display scale fidelity (Log Amp)

− Log response & display scaling digitally

synthesized

Frequency

Dependent Frequency

Independent


37

Digital IF Improves Amplitude Accuracy

Input

Connector

Down-

conversion

IF

Gain

IF

Filter

Log

Amp Video

Filter

RF Input

Attenuator 2 dB Steps Pre-selector

Log ADC

ADC DSP

Digital IF improves Amplitude Accuracy:

• Ref Level switching uncertainty (IF gain)

− Level correction digitally synthesized

• RBW filter switching uncertainty

− RBWs all digitally synthesized

• Display scale fidelity (Log Amp)

− Log response & display scaling digitally

synthesized

Frequency

Dependent Frequency

Independent

Amplitude

Uncertainty

N9038A

Receiver Analog IF

(older receivers)

Ref Level

Switching 0dB <= +/- 1dB

RBW

Switching +/- .05dB <= +/- .5dB

Display Scale

Fidelity +/- .15dB <= +/- .85dB


38

Specifications: Scan Speed

• Need for SPEED

– DUTs that require short measurement time (ex. motor starter)

– Test MORE devices

– Shorter turn-around-time

• Depends On:

– Scan type (Stepped, Swept, Time Domain)

– Resolution Bandwidth

– Dwell Time

– RF Preselector

– Other?


39


• Overview





• Q&A


40

41

Making an emissions measurement

Pre-scan

Data Reduction

Maximization

Final Measurement

Report Generation

• Recommended by CISPR

• Measurement methodology

found in CISPR 16-2-3

• Fastest way to make the

measurement

• MIL Measurements*


• Preview spectrum

using “Peak” detector

• Measurement Parameters

– Frequency range

– Limit lines

– Margins

– Antenna Factors

– Scan Type

• Scan Types

– Stepped

– Swept

– Time Domain

Pre-Scan

42

Pre-scan Data Reduction Maximization Final

Measurement Report

Generation

Prescan


Data Reduction

• Signals exceeding the limit are automatically:

– Marked in red

– Peaks are marked with white “X”

– Added to signal list

• Only do final measurement on signals exceeding the limit and margin

– Don’t measure unnecessary signals

– Saves time

43


Measurement Report

Generation

Signal List


Maximization Techniques Maximize signal amplitude before final measurement


44


Measurement Report

Generation

• Monitor Spectrum

– Simultaneous spectrum and meter measurements

– Access to signal (suspect) list

– Meter max hold

• Spectrum Analyzer mode

– Switch between EMI receiver and SA

modes using global center frequency

– Powerful analyzer mode

Receiver mode

Spectrum Analyzer Mode

Final Measurement


45


Measurement Report

Generation

• Signals in list are

automatically

measured

• Measure suspect signals

with Quasi-peak, EMI

average detector, etc.

• Suspect signals still

failing? Start

troubleshooting?

Report Generation


46


Measurement Report

Generation

• Report Generator

– Settings

– Screenshots

– Tables Report Format: PDF or HTML


• Overview





• Q&A


47

Transducers for EMI measurements

• Near Field Probe

• Near Field Scanner

• Line Impedance Stabilization Network (LISN)

• Antennas

• Other devices?


48

“a device that receives a signal in the form of one type of energy

and converts it to a signal in another form” -dictionary.com

Near Field Probes – E & H Field

• Use Cases

– Pre-compliance

– Diagnostics

• Characteristics

– Frequency Range

– Spatial Resolution

– Sensitivity

• Measure or Generate Fields

– Emissions or Susceptibility

49

E Field Probe

H Field Probe


Near Field Scanners


50

LISN: Line Impedance Stabilization Network

• Typically used for conducted emission measurements

• Isolates the power mains from the EUT

• Isolates EUT from the power mains

• Powers the EUT and couples signals to EMI receiver

Power Mains

EUT

No Transient

Limiter Required

LISN

MXE Receiver

Types of LISNs

• V-LISN

• Delta LISN

• T-LISN


51

EMI Broadband Antenna Examples

Double ridged horn

Hybrid Log Periodic

Biconical

Log Periodic Hybrid Log Periodic


52

http://tdkrfsolutions.com/WebDataSheets/HLP-2601WebSheet.htm

“Ratio of the electric field to the

voltage out of the antenna”

AF = 𝐸𝑖𝑛

𝑉𝑜𝑢𝑡

Understanding Antenna Factors


53

AF = Antenna Factor (1/m)

E = Electric Field units (V/m)

V = Voltage output from antenna (V)

Log Units

Linear Units

AF(dB/m) = E(dBµV/m) –V(dBµV)

Typical biconical antenna factors

Ante

nna F

acto

r (d

B/m

)

Frequency (MHz) 20 150 300

20

10

Antenna Factors on a Typical Display


54

Corrected

for a

broadband

antenna

Examples of Test Facilities


55

5 Meter Semi Anechoic* Chamber (Located on the Agilent Santa Rosa site)

This chamber uses 2 antenna

towers, one for vertical and

one for horizontal polarization.

*Anechoic material is made

of carbon impregnated

rubberized cones or ferrite

tiles or both

Origin

Anechoic

an- “not” + echoic (echo)

Examples of Test Facilities


56

Open Area Test Site (OATS)

• Useful in low ambient signal

environments

GHz Transverse Electro Magnetic Cell

(GTEM Cell)

• Used for smaller devices. Can be

used for immunity and emissions.

Reverberation Chamber

• Uses a mode stirring tuner to

generate a uniform field (no

absorption material on the walls)

Automation Software

Reasons for Automation

-Supplement skill and knowledge of the tester

-Measurements repeatability

-Results are presented in a common format

-Reduce test time by automating setups

-Run turntables and antenna towers

Types of Automation

-Internally executed application such as N6141A EMI Application

-PC based applications

Software Available


57

http://www.ets-lindgren.com/


58

Automation Software

Receiver

Chamber Control

Room • Automation software typically

communicates with the receiver

over LAN or GPIB

• Uses SCPI commands

Questions? Please type them in the chat box now


59

N9038A MXE EMI Receiver X-Series Signal/Spectrum Analyzers

www.agilent.com/find/mxe

www.agilent.com/find/x-series

http://www.agilent.comfind/mxe

http://www.agilent.com/find/x-series



EMC Back to Basics 2014 - · PDF fileCISPR 22 - Information ... • What is CISPR 16-1-1? Specifies the characteristics and performance of equipment for the measurement of radio disturbance

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