Agilent_EMC_measurements.pdf

8/14/2019 Agilent_EMC_measurements.pdf

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Misure di compatibilita

Elettromagnetica

Roberto Sacch i

Electronic Measurements GroupAgilent Technologies


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Agenda Introduzione alle misure EMI

Terminologia;

Sistema di misura (antenna, LISN, ricevitore, etc.);

Detectors;

Normative europee ed internazionali

Misure di compatibilita elettromagnetica Misure di emissioni radiate

Misure di emissioni condotte Misure di immunita(EMS)

Setup di misura

Camere anecoiche vs. OATS (Open Area Test Site)

Soluzioni Agilent Introduzione al nuovo ricevitore EMI Full Compliance Agilent MXE

Uso degli analizzatori Agilent della Serie-X per misure EMI pre-compliance.

Sorgenti per i test di immunita

Software applicativo

Soluzioni complete tramite i nostri partners

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Pre-compliance vs. Full compliance measurements

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Pre-compliance measurements

Evaluate the conducted and radiatedemissions of a device using correct

detectors and bandwidths before going

to a test house for compliance testing

Full Compliance measurementsFull compliance testing requires a receiver

that meets all the requirements of CISPR

16-1-1 (response to a CISPR pulse gen), aqualified open area test site or semi

anechoic chamber and an antenna tower

and turntable to maximize EUT signals.


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What is EMC?

Electromagnetic Compatibility (EMC): The ability of equipment to function

satisfactorily in its electromagnetic environment without introducing intolerabledisturbances into that environment or into other equipment.

Combination of Interference and Immunity.

Electromagnetic Interference (EMI):Electromagnetic energy emanating from one device which causes another device to

have degraded performance.

Electromagnetic Immunity (Susceptibility, EMS): Tolerance in the presenceof electromagnetic energy (Performance degradation due to electromagnetic energy).

Compliance measurements require a receiver that meets the requirements of

CISPR part 16 (for commercial) or MIL-STD-461 (for military).

All EMI receivers require a pre-selector at lower frequencies to limit the input energy

and maintain sufficient dynamic range to meet the CISPR 16 requirements.


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Definitions

EMCElectroMagnetic Compatibility

EMIElectroMagneticInterference

EMS

ElectroMagneticSusceptibility

(aka Immunity)


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EMI measurement system


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Compliance EMI receiver requirements

A CISPR 16-1-1 receiver must have the following functionality in

the range 9 kHz - 18 GHz:

A normal +/- 2 dB absolute accuracy

CISPR-specified resolution bandwidths (-6 dB)

Peak, quasi-peak, EMI average, and RMS average detectors

Specified input impedance with a nominal value of 50 ohms; deviations

specified as VSWR

Be able to pass product immunity in a 3 V/m field

Be able to pass the CISPR pulse test (implies pre-selector below 1 GHz)

Other specific harmonic and intermodulation requirements

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Receiver requirements above 1 GHz

Above 1 GHz regulations require:

1 MHz bandwidth for measurements

No quasi-peak detector

No CISPR pulse test, meaning no additional pre-selector required

excellent sensitivity

According to current FCC regulations, the maximum test frequency is the

fifth harmonic of the highest clock frequency for an unintentional radiator(for example, computers without wireless connectivity) and the tenth

harmonic for an intentional radiator (such as a cellular phone or wireless

LAN).

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What is an EMI Receiver?Lets begin with a spectrum analyzer

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Display and measure amplitude versus frequency for RF & MW signals

Separate or demodulate complex signals into their base components (sine waves)

Spectrum Analysis


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OverviewTypes of Tests Made

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Modulation

Noise

Distortion

EMC


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Architecture of Modern Spectrum/Signal Analyzers

What does Modern mean?

Digitize the IF output, not detector output

FFT and swept capability (neither one is optimum for everything)

Data output available

Connectivity

Automated measurement features Ability to use new features and duplicate or expand necessary old ones

Complete spectrum analyzer & vector signal analyzer


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Theory of OperationSwept Spectrum Analyzer Block Diagram

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Pre-Selector

Or Low PassInput Filter

Crystal

Reference

Oscillator

Log

Amp

RF inputattenuator

mixer

IF filter

(RBW)envelope

detector

videofilter

local

oscillator

sweep

generator

IF gain

Input

signal

ADC, Display

& Video

Processing


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Traditional Spectrum Analyzer

Scalar analysis

Digitizing the video signal

Classic superheterodyne swept spectrum analyzer

Product detector

loss of phaseinformation


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Digital IF Spectrum/Signal Analyzer

Vector data CAN be preserved (mag/phase or I/Q)

Digitizing the IF Signal

Some troublesome operations

and conversions are now

fast, accurate DSP


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OverviewDifferent Types of Analyzers

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Parallel filters measured

simultaneouslyA

ff1 f2

FFT Analyzer

A

ff1 f2

Filter 'sweeps' over

range of interest

Swept Analyzer


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SpecificationsResolution: RBW Type Determines Sweep Time

280 sec134 sec

13.5 sec

8563E Analog RBW

PSA Digital RBW

PSA FFT RBW


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Speed Improvements

Useful comparisons highly specific, many factors

PXA mode switching typically faster than PSA

Where speed is critical, consider modifying measurement routines to

include features such as list sweep

Benchmark PXA PSA Speedimprovement

Preset (*RST) 28 ms 168 ms 6x

Marker peak search 6.5 ms 78 ms 12x

Local Update 13 ms 17 ms 1.3x

CF Tune and Transfer (4 - 5GHz) 109 ms 186 ms 1.7xRemote sweep and trace transfer 18 ms 30 ms 1.67x

Nominal speed comparison, PSA example:


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Modern spectrum analyzer

Resolution BW Selectivity or Shape Factor

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3 dB

60 dB

60 dBBW

60 dB BW3 dB BW

3 dB BW

Selectivity =

Determines resolvability of unequal amplitude signals


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Specifications

Resolution: RBW Type and Selectivity

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DIGITAL FILTER

ANALOG FILTER

SPAN 3 kHzRES BW 100 Hz

Typical

Selectivity

Analog 15:1

Digital 5:1


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Digital Filter Shape

Better shape factor, biggest selectivity benefit for different signal levels

Equivalent selectivity at a wider, faster-sweeping RBW

digital filters swept an additional 3-4x faster

30 kHz Digital Filter


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MIL-STD-461 Bandwidth Requirements

Measurement Range -6dB Bandwidth

30Hz - 1 KHz 10 Hz

1 KHz -10 KHz 100 Hz

10 KHz - 150 KHz 1 KHz150 KHz - 30MHz 10 KHz

30 MHz - GHz 100 KHz

> 1GHz 1 MHz

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Some modern analyzers approach accuracy of power meter + sensor

Even better for low-level signals, with narrower noise bandwidth andthe benefit of frequency selectivity

Some factors determining uncertainty:

Input connector (mismatch)

RF input attenuator

Mixer and input filter (flatness)

IF gain/attenuation (reference level)

RBW filters

Display scale fidelity

Calibrator

Modern Spectrum Analyzer Accuracy


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Modern Spectrum Analyzer Accuracy Examples


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Line Impedance Stabilization Networks (LISN)

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Purpose of a LISN:

1. Isolates the power mains from theequipment under test. The power

supplied to the EUT must be as clean as

possible. Any noise on the line will be

coupled to the X-Series signal analyzer

and interpreted as noise generated by

the EUT.

2. Isolates any noise generated by the EUT

from being coupled to the power mains.

Excess noise on the power mains can

cause interference with the proper

operation of other devices on the line.

3. The signals generated by the EUT are

coupled to the X-Series analyzer using a

high-pass filter, which is part of the LISN.

Signals that are in the pass band of the

high-pass filter see a 50- load.


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LISN

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LISN

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@ Electrical Network Frequency

@ 150 kHz to 30 MHz


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Transient Limiter

The purpose of the limiter is to protect the input of the EMC analyzer from

large transients when connected to a LISN. Switching EUT power on or offcan cause large spikes generated in the LISN.

The Agilent 11947A transient limiter incorporates a limiter, high-pass filter,

and an attenuator. It can withstand 10 kW for 10 sec and has a frequencyrange of 9 kHz to 200 MHz. The high-pass filter reduces the line frequencies

coupled to the EMC analyzer.

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DUT

LimiterLISN


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Field Strength and Antenna factors

Radiated EMI emissions tests measure the electric field. The

field strength is calibrated in dBV/m.

Antenna factors is the ratio of the electric field (V/m) present

at the plane of the antenna versus the voltage out of the

antenna connector.

Log units:

AF(dB/m) = E(dBV/m) - V(dBV)E(dBV/m) = V(dBV) + AF(dB/m)

Notes:

Antenna factors are not the same as antenna gain.

dBV = dBm + 107

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Detectors: Convert IF Samples to Display Bins or

Buckets

Multiple simultaneous detectors

Screen Shot Detector 3types

Time

Volts

Peak

Neg Peak

Sample

Display points or

buckets

Normal, Average, Neg Peak

Peak, Neg Peak, Sample


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Detectors

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Most radiated and conducted limits are based on quasi-peak

detection mode.


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Peak QP AveragePeak Detector

Initially used

Faster than QP and Average modes

If all signals fall below the limit, then the product passes and no futuretesting is needed.

QP

For CW signal, Peak = QP

Much slowerby 2 or 3 order magnitude compared to using Peak detector

Charge rate much faster than discharge rate

the higher repetition rate of the signal, the higher QP reading

Average

Radiated emissions measurements above 1 GHz are performed usingaverage detection

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Close field probe

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Measures the magnetic field H strength at the centerof its sense loop. The plane of the probe tip loops

must be perpendicular to the radiating magnetic field


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Test example

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International emissions regulations (summary)

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CISPR changes

RMS-Average

Preselector-less testing: enables use of spectrum analyzer for specific

test cases.(no emissions with PRF < 20 Hz)

CISPR 22 to 6 GHz

Time Domain: sometimes required for the automotive market

APD: soon to be required by CISPR11

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G l P f M ki EMI M t


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General Process for Making EMI Measurements

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Determine the country or countries in which the productwill be sold which in turn identifies the regulator agency.

Select the limit lines to be tested to (conducted/radiated).

Select the band to be used.

Correct for transducer loses and amplifiers gains.

Identify signals above the limit that must be evaluated.

Zoom in on failed signal and perform quasi-peak or

average measurements.

C d t d E i i M t


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Conducted Emissions Measurements

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1. Connect DUT to the test system

2. Set the proper frequency range3. Load limit lines and correction factors for LISN and limiter

4. View the ambient emissions with DUT OFF

5. Switch on the DUT and find signals above limits by using peak detector

6. Measure all signals above limits with quasi-peak and average detectors


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R di t d E i i M t


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Radiated Emissions Measurements

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1. Connect the antenna

to the EMI receiver and

separate the antenna fromthe DUT as specified by the

regulation requirements

2. Set the proper frequency

range and bandwidth

3. Load limit lines and

correction factors for

antenna and cable.

4. With DUT OFF, measure the ambient emissions and store them

5. Switch on the DUT and find signals above limits by using peak detector (only those

not present during the ambient scan). Rotate the DUT to maximize the emissions.

6. Measure all signals above limits with quasi-peak and average detectors

O A T t Sit (OATS)


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Open Area Test Site (OATS)

EUTs are measured in an open area test site (OATS) or anechoic chamber.

ANSI C63.4 and CISPR 16-1-1 specify the requirements for an OATS, including: Preferred measurement distances

of 3, 10, and 30 meters

Antenna positioning at 1 to 4 meter

Heights

An area called the CISPR ellipseof major diameter 2X and minor

diameter 3 X, where X is themeasurement distance; the ellipse

must be free of any reflecting objects

A metal ground plane for the measurement area

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Note: 10 meter anecho ic ch ambers and GTEM cel ls can also be used fo r radiated

com pl iance measurements.

1 Select the measurement range


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1. Select the measurement range

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2 Load Corrections factors


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2. Load Corrections factors

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Amplitude at

point circled

Amplitude

referenced toblue line


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Troubleshooting


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Troubleshooting

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Use the close-field probe to locate the sources of the radiated signals

exceeding the limit lines

Immunity test setup


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Immunity test setup

Conducted Immunity

100 kHz 1 GHz

Amplifiers

HF-Switch

Radiated Immunity

30 MHz 18 GHz


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Agilent Solutions

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What is a CISPR 16-1-1 Compliant Receiver


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What is a CISPR 16-1-1 Compliant Receiver

CISPR 16-1-1 is the document that defines the

functionality of an EMI receiver

Detectors

N9038A MXE EMI receiver is CISPR 16-1-1 2010 Compliant

Frequencyresponse

CISPR is a subcommittee of the IEC

What is the MXE EMI Receiver?


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X-Series

signalanalyzer

CISPR 16

compliantEMI receiver

What is the MXE EMI Receiver?

The Agilent MXE is more than a CISPR 16-1-1 compliant EMI

receiver

It is also an X-Series signal analyzer that can run a variety of

measurement applications

The MXE can evolve as technology changes

N9038A MXE EMI Recei er


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20 Hz to 1 GHz forConducted Emissions

(built-in limiter)

20 Hz to 26.5GHz for

Radiated

Emissions

CompliantPreselection 20 Hz

to 3.6 GHz in both

EMI Receiver

Mode and SA

Mode on

Both Inputs

CISPR 16-1-1 2010Compliant EMI Receiver

N9038A MXE EMI Receiver

in 30 seconds

Run X-Seriesapplications


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L

CF

RF

IN

DDS

Noise Source

20 Hz -1GHz

Agilent X-Series Signal Analyzers


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Agilent X-Series Signal Analyzers

Multiple instruments in one box: Swept spectrum analyzer;

FFT analyzer;

RF and Baseband Vector Signal analyzer;

Noise Figure analyzer. Fastest signal analysis measurements

Broadest set of applications and demodulation capabilities

Upgradeable HW

Most advanced user interface & world-class connectivity

Instrument Architecture


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Instrument ArchitectureModern Spectrum Analyzers Architecture (PSA, X-Series)

RF Section IF Section BB Section

AttenuationFiltering

Downconversion RBW Filtering Envelope Detection Log Conversion VBW Filtering

Peak/sample/rmsdetection

Averaging

ADCIF/BB Section

on ASIC

All Digital IF Architecture

Modern Spectrum Analyzer Block Diagram


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Modern Spectrum Analyzer Block Diagram

YIG ADC

Analog IFFilter

Digital IF Filter

Digital Log Amp

Digital Detectors

FFT

Swept vs. FFTAttenuation

Pre-amp

Replaced

by

All Digital IF Advantages


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All Digital IF Advantages

RF Section ADC IF/BB Sectionon ASIC

Flexibility:

RBW filtering in 10% steps

Filters with better selectivity Multiple operation modes (Swept, FFT, VSA, NFA)

Accuracy:

Log conversion practically ideal

No drift errors; increased repeatability

Speed:

When Swept mode is slow, go FFT

FFT

Techniques for Reducing DANL, Improving Dynamic


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q g , p g y

Range

Reduce attenuation

Add preamp

Reduce RBW

Add external filtering

Better/shorter cables, connectors

Move analyzer closer

Time averaging (where possible, not measurement avg.)

Measurement processing (take advantage of Moores Law)

Noise power subtraction/noise correction/NNC

Noise floor extension (NFE) leverages deep knowledge ofanalyzer/circuit behavior

CW Signal Measured Near Analyzer Noise Floor


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g y

Actual S/NDisplayed

S/N

CW Signal

Apparent

Signal

This is

fundamental, and

often missedAmpl & Freq

Axes Expanded

Example: No noise subtraction or near noise correction


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Noise Subtraction, Noise Floor Extension


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,

New technique NFE improves D.A.N.L.

analyzer noise power calculated/subtracted real time

3 dB error

without NFE

No error

Improved noise floor

or displayed averagenoise level

Analyzer Noise Floor with NFE


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Source still off, green trace shows analyzer noise level with NFE

Other measurement conditions unchanged

Note high variance result from subtraction of small, noisy numbers

Analyzer DANL now far enough below source for minimal(0.2 - 0.4 dB) error

A Closer Look


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Pink trace adds to blue trace; result is yellow trace (NFE not used)

Green trace is included in blue trace but resulting error very small

Source noise Level, no NFE

Source Noise Level, with NFE

Analyzer Noise, no NFE

Analyzer Noise with NFE

EMC Features standard in all X-Series Spectrum


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EMI Roadmap

6/28/2011Page 70

p

analyzers

Limit Lines(2000 pts)

Amplitude correction (2000 pts) 40001 sweep points

Option EMC in X-Series spectrum analyzer


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p p y

CISPR 16-1-1 detectors

(to latest spec)Quasi Peak

EMI Average (CISPR-AVG)RMS Average (CISPR-RMS)

EMI Bandwidths (CISPR & MIL STD)

EMI Presets

Tune & Listen

Measure at Marker

EMI Peak, EMI Average, and

Quasi Peak measurements

displayed together

W/N6141A EMC measurement application


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Full Featured Pre-compliance Application

Available in all X-Series models

pp


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N6141A measurement: Frequency Scan w ith Log Display


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- same functionality as E7400 Signal List

Meters tune

to selected

signal

N6141A measurement: Str ip Chart Patent


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EMI Roadmap

6/28/2011Page 77

p

Time recordof zero span

data scrolls

to left Up to three

different

detectors

Can be usedto make

click

measure-

ments

Click measurements are made on home appliances

Patent

Applied

For

Option EDP (Enhanced Display Package) for the SA


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Spectrogram

Trace Zoom

Zone Span

Group/Presentation Title

Agilent RestrictedPage 78

N6141A EMI Measurement Application


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Pre-complianceCompliance

PXA

MXA

CXAAgilent MXE N9038A

EXA

Agilent products for Immunity test (EMS)


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Signal

generator

9 kHz 3 GHz, AM, FM, Phase, Pulse IQ Modulator,

40 MHz Mod.-BW

Signal

generator

N5182, N5182, N5183

100 kHz- 1,3, 6, 20, 40 GHz, AM, FM, Phase, Pulse,

optional vector, 120 MHz Mod.-BW, step , sweep,

USB-Power meter included

Power meter/

Power sensors

E441x, E191x, N8262, U200x

100 kHz 40 GHzsingle channel, dual channel, USB, peak, envelope,

pulse

Accessories Directional Couplers, cables, Adapters, Switches etc.

Solution partners for EMC
http://www.home.agilent.com/agilent/product.jspx?nid=-35560.695944.00&cc=US&lc=enghttp://www.home.agilent.com/agilent/product.jspx?nid=-536902901.899991.00&cc=US&lc=enghttp://www.home.agilent.com/agilent/product.jspx?nid=-536902903.689086.00&cc=US&lc=eng


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Complete solution:

1. Automation software

2. Chambers

3. GTEM

4. Antennas

5. Power amplifiers

6. Accessories

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Per documentazione su prodotti ed applicazioni EMI/EMC


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visitare il sito

http://www.agilent.com/find/EMC

Contatti:

Agilent Technologies ItaliaRoberto Sacchi

Application EngineerE-mail: [email protected]

Giuseppe SavoiaSignal Analysis and Generation Sales SpecialistE-mail: [email protected]

Agilent Contact CenterE-mail: [email protected]: 02 9260 8484
http://www.agilent.com/find/EMCmailto:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]://www.agilent.com/find/EMC

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Agilent_EMC_measurements.pdf