EMC / ESD Pulse MeasurementsUsing Oscilloscopes – September 2016
978-1-5090-1416-3/16/$31.00 ©2016 IEEE
Contents
• EMC Measurement Categories and Requirements
• ESD Pulse Test Requirements and Measurement Thresholds
• Sequenced Acquisition for EFT (Electrical Fast Transient) Debug
• Surge Testing
• MIL-STD-461G
• Voltage Testing Below Battery Level
• Sample Rate and V/div Effect on ESD Pulse Measurements
• Level-At-Pulse, Time-To-Value, and Parameter Limiters
• ESD RC Time Constant Measurement
• Radiated Immunity Testing
Radiated
EmissionsWill the EUT create
emissions that interfere
with the operation of
other products?
Conducted
EmissionsHow much noise
voltage is injected back
into the mains by the
EUT?
Radiated
ImmunityWill the EUT be
susceptible to emissions
from other devices,
either through the air or
via cables?
Conducted
ImmunityWill the EUT be
susceptible to transients
generated by switching
of capacitive or
inductive components?
Quadrants of EMC/ESD Testing
Oscilloscopes are used for: Radiated Immunity
Conducted Immunity
Conducted Immunity Pulsed EMI tests include: ESD (Electrostatic Discharge)
EFT (Electrical Fast Transient)
Surge Testing
EUT = Equipment Under Test
ESD Pulse Test
Requirements
Conducted Immunity General Test Requirements
Generate a Burst, Surge, or ESD pulse
Verify the pulse shape from the generator using an oscilloscope, verifying parameters such as:
Rise Time
Fall Time
Pulse Width
Frequency
Pulse Repetition interval
Burst Repetition interval
Ensure that the DUT still operates correctly during test, for example:
Automotive engine control unit still transmits proper messages
Telecom board serial data messages are uncorrupted
Consumer electronics item still functions
ESD Standards examples:
IEC 61000-4, EN 61000-4, ITU, UL, FCC, Telcordia, ANSI, Bellcore, ISO10605:2001, ISO10605:2008, MIL-STD-461G, proprietary military, proprietary automotive, etc.
The majority of Immunity Testing follows the IEC 61000 (CE Mark)
Diagram of ESD calibration using scope
ESD Testing – Electrostatic DischargeMeasurement Steps
Typical Pulse Characteristics
Trise = 0.7 to 1.0 ns
Tfall = 0.7 to 1.0 ns
Measurement Needs
Capture a Single Pulse
Measure one pulse, verify rise time
for positive pulses, verify fall time for
negative pulses
1 GHz, 2 GHz, or 4 GHz+ scope
depending on standard specification
How is risetime measured on this ESD pulse?
10%-90% risetime measurement first requires the
determination of 0% and 100% levels.
Pulse Measurement Definitions
IEEE Standard Pulse DefinitionsHow Oscilloscopes Measure Pulse Parameters
Oscilloscopes determine pulse parameters from Top and Base values
IEEE Pulse Definitions How Pulse Measurements Are Determined
Pulse measurement definitions are defined by the
IEEE Std 181-2003 "IEEE standard on
transitions, pulses, and related waveforms"
Oscilloscopes conform to the IEEE pulse
measurement definitions, and Top and Base are
determined statistically based on the two modes
of a voltage level histogram.
Top and Base form the 100% and 0% reference
levels which are used for measurements such as
amplitude, risetime, falltime, period, frequency,
width, duty cycle, overshoot, and virtually every
timing measurement.
Top and Base must first be calculated correctly in
order for timing and amplitude measurements to
produce the correct measurement result.
Clock Top and Base are correctly determined from a voltage histogram
Clock pulses with clearly
delineated Top and Base
Top
Base
Two main
modes emerge
from the voltage
level histogram,
identifying the
steady state
values of Top
and Base
Top and Base are not meaningful for ESD pulse measurements
ESD pulse
What happens when
standard pulse parameters
are applied to an ESD
waveform?
A voltage level histogram of this ESD pulse
does not result in the identification of two
main modes. Standard pulse parameters
will not yield correct results in this case.
Top
Base
ESD Top and Base are not meaningful for pulse measurements
With Top (100%) and Base (0%) identified in the
following locations, the 10%-90% risetime
measurement will only encompass a very small portion
of the total ESD pulse rising edge
Base
Top
Different than IEEE pulse definitions, EMC pulse
definitions (for example the IEC 61000-4-2 standard)
use 0% and Max, instead of Top and Base to calculate
10%-90% risetime
An oscilloscope must use 0% and Max thresholds in
order to perform the EMC-specific measurement
EMC pulse measurements now require the use of
thresholds set to 0% and Max (where Max is the peak
voltage level of the waveform), instead of Top and
Base, to meet the measurement specification. Modern
oscilloscopes have begun to allow for EMC pulse
parameter measurements using threshold settings of
peak-to-peak, 0% to Max, and 0% to Min along with
the standard absolute or percent levels.
ESD Pulse Rise Time Definitions Require 0% and Max
Risetime calculated using standard IEEE pulse parameter definitions
Risetime is incorrectly calculated as 494 picoseconds on this ESD
pulse. Note the risetime detailed marker location.
Risetime calculated using EMC thresholds
Risetime is correctly calculated as 854
picoseconds on this ESD pulse
Max
0%
Effect of thresholds on the Width
measurement of this ESD pulse
Effect of thresholds on the Width
measurement of this ESD pulse
Standard and EMC thresholds for ESD pulse width
The pulse width and risetime are measured, both with and without EMC
thresholds applied. In parameter 1 (P1), the thresholds are set to 0% - Max, and
the pulse width is measured correctly as 2.109 nanoseconds. In parameter 2
(P2), the thresholds are set to the standard scope threshold of 50% of Top and
Base. In this case, the measurement is incorrectly reported as 50.348
nanoseconds -- an error of 2287%. The width measurement was impacted so
significantly, that the 50% threshold between Top and Base actually produced a
width measurement on the wrong pulse shape. Parameter 3 (P3) is set to the
correct EMC threshold of 0% to Max, producing a correct electrostatic pulse
risetime measurement of 833 picoseconds. Notice that in parameter 4 (P4), the
standard risetime is incorrectly reported as 873 picoseconds. When using
standard pulse parameter measurements, erroneous values can be obtained.
Use of standard pulse thresholds produced a
2287% measurement error on this ESD pulse. Note
the threshold indicated in the width@level
parameter marker for each.
EMC Level-At-Pulse,
Time-To-Value,
Parameter Limiting
EMC Level-At-Pulse Parameter
EMC Level-At-Pulse Parameter
EMC Level-At-Pulse Parameter
EMC Time-To-Half Value Parameter
Parameter limiting technique for ESD width measurement
Because EMC pulses often have pulse perturbations on the falling edge of the pulse, these
can result in false measurement readings when using standard parameters. For example,
if the falling edge had ringing oscillations which repeatedly crossed the threshold, then
multiple false width readings would be possible. For this reason, a measurement filtering
capability which can limit the number of pulses the scope measures in an acquisition is
needed. This measurement filtering capability, now available on modern scopes, allows for
pulse-like perturbations on the falling edge of a pulse to be ignored and excluded from the
measurement results. Parameter statistics could be accumulated on the first pulse in
conjunction with parameter limiting subsequent perturbations.
A Parameter Limiter Is Needed To Avoid Measuring The Bounce Areas As Widths
Parameter Limiter Isolates Correct Width
ESD Verification
Test Setup Example
current shunt
target
• 20 dB attenuator connects to
current shunt target output
• double shielded cable leads to
6 dB attenuators on input of
scope
Verification Of The Output Characteristics Of The Test Pulse Generator
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Verification Of The Output Characteristics Of The Test Pulse Generator
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Verification Of The Output Characteristics Of The Test Pulse Generator
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Using 0% - Max Thresholds for ESD Rise Time Measurement
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Calculating ESD Pulse Maximum (first peak current)
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Voltage level calculation at 400 ns delay after 50% incident pulse level (current at t1)
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Voltage level calculation at 800 ns delay after 50% incident pulse level(current at t2)
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ESD pulse parameters of rise time, first peak current, and currents at t1 and t2
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Rise time
First peak current
Current at t1 Current at t2
Sample Rate's Impact On Rise Time
For ESD Pulse Measurements
Effect of Sample Rate On ESD Rise Time Measurements
ESD pulse sampled
at 40 GS/s
ESD pulse sampled
at 4 GS/s
ESD pulse sampled
at 2 GS/s
ESD pulse sampled
at 1 GS/s
Approximately 50 sample
points on rising edge
Approximately 5 - 6 sample
points on rising edge
Not enough sample
points to correctly
characterize rising edge
Not enough sample
points to correctly
characterize rising edge
Effect of Sample Rate On ESD Rise Time Measurements
ESD pulse sampled
at 40 GS/s
ESD pulse sampled
at 4 GS/s
ESD pulse sampled
at 2 GS/s
ESD pulse sampled
at 1 GS/s
Measured rise time:
839 ps
Measured rise time:
865 ps
Measured rise time:
1.070 ns
Measured rise time < 1.54 ns,
and measurement warning is
reported
(3% measurement error)
Sample Rate Goal for ESD Pulses:
Rule Of Thumb: Acquire At Least 10 Sample Points On The Rising Edge
Measured risetime
result is within one
half of one percent
(measurement result is
within 0.5% of 839 ps)
50 sample pts on
rising edge
10 sample pts on
rising edge
Measurement Method Background:Sparse Math Operator Was Used To Isolate Sample Rate Effect On Same Input Waveform
Measurement Method Background:Sparse Math Operator Was Used To Isolate Sample Rate Effect On Same Input Waveform
Measurement Method Background:Sparse Math Operator Was Used To Isolate Sample Rate Effect On Same Input Waveform
Dynamic Range and Signal Integrity
For ESD Pulse Measurements
Dynamic Range and Signal Integrity For ESD Pulse MeasurementsThis Concept Holds True for All Digitizing Real Time Scopes
8 vertical bits (256 ADC levels)
available at full scale
or 12 vertical bits (4096 ADC levels)
available at full scale
7 vertical bits (128 ADC levels)
available at full scale
or 11 vertical bits (2048 ADC levels)
available at full scale
Dynamic Range and Signal Integrity For ESD Pulse MeasurementsThis Concept Holds True for All Digitizing Real Time Scopes
6 vertical bits (64 ADC levels)
available at full scale
or 10 vertical bits (1024 ADC levels)
available at full scale
Dynamic Range and Signal Integrity For ESD Pulse MeasurementsThis Concept Holds True for All Digitizing Real Time Scopes
Scope Block Diagram Shows Why Maximizing Waveforms In Grid Maximizes Measurement Accuracy This Concept Holds True for All Digitizing Real Time Scopes
Surge Testing
Surge Testing General Test Requirements
Pulse Characteristics
Trise = typically 1.2 to 10 ms
Tfall = typically 20 to 10,000ms
Measurement Needs
Rise time
Pulse Width
Maximum
Area
Charge
A Surge pulse also does not have a clearly-defined Top and Base
The pulse characteristics of a surge pulse also do not conform to the
IEEE pulse parameter definitions, because the surge does not have high
and low steady-state values. After a fast linear rise to a sharp peak, the
waveform then exponentially decays toward, but does not quickly reach,
an asymptote. With no steady-state values, the surge will produce
indeterminate Top and Base values. Because Top and Base must be
determined in order to calculate the thresholds used for risetime,
falltime, and pulse width, the measurements therefore become invalid
when using traditional oscilloscope clock pulse parameters.
Hardware Configuration for Surge Verification
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Teledyne LeCroy in cooperation with Hitachi Automotive Systems
Hardware Configuration for Surge Verification
Surge Verification Measurements Including Rise Time, Pulse Width, Maximum, Area, and Charge
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Application example:The ISO10605:2008 standard requires
the measurement of 10 consecutive parameter values
ISO10605:2008 pulse measurement statistics of 10 consecutive acquisitions
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Histogram statistical distribution of 10 consecutive acquisitions
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Application example:The ISO10605:2001(E) standard (pg 13) requires the
measurement of the RC time constant value of the
decay of an air discharge ESD pulse.
A location is referenced at a stable point on the waveform,
then a second point is located at 37% voltage level of the
first value. The time difference between the two points
is calculated to determine the RC time constant
of the decay time.
Hardware setup for RC time constant measurement
Published: 978-1-5090-1416-3/16/$31.00 ©2016 IEEE
ISO10605:2001(E) RC time constant measurement
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ISO10605:2001(E) RC time constant measurement
Published: 978-1-5090-1416-3/16/$31.00 ©2016 IEEE
ISO10605:2001(E) RC time constant measurement script
Published: 978-1-5090-1416-3/16/$31.00 ©2016 IEEE
Script used to measure the RC Time Constant
Set app = CreateObject("LeCroy.XStreamDSO") ' ActiveX COM handle
numSamples = InResult1.Samples ' number of sample points in acquisition
scaledData = InResult1.DataArray(True) ' waveform sample points array
If (app.Measure.P1.Source1) <> "F4" Then ' if the source for P1 isn't F4
app.Measure.P1.Source1 = "F4" ' then set it to F4
app.Measure.P1.Source2 = "None" ' and set the other input to be blank
End If ' Force F4 to be the input source for this script at all times
trigpt = app.Math.F4.Out.Result.HorizontalOffset ' Determine the trigger point / horizontal offset
sampleres = app.Math.F4.Out.Result.HorizontalPerStep ' Determine the spacing between sample points
horzunits = app.Math.F4.Out.Result.HorizontalUnits ' Query for units (e.g. Seconds, etc.)
vertunits = app.Math.F4.Out.Result.VerticalUnits ' Query for units (e.g. Volts, etc.)
x2_array_position = numSamples - 35000 ' hardcoded value for X2 that placed it on the rightmost graticule on the screen
x2_time_position = trigpt + (sampleres * x2_array_position) ' calculate the rightmost falling edge value in terms of time (rather than an array index)
e_constant = 0.367879441 ‘value from ISO spec
i = x2_array_position ' counter position
x1_target_value = scaledData(x2_array_position)/(e_constant)
Do While (scaledData(i) < x1_target_value) And (i > 1)
i = i - 1
Loop
x1_array_position = i
x1_time_position = trigpt + (sampleres * x1_array_position)
x1_vertical_position = scaledData(x1_array_position)
x2_vertical_position = scaledData(x2_array_position)
labelsposition = Cstr(x1_time_position) & "," & Cstr(x2_time_position)
app.Math.F4.ViewLabels = True ' turn label display on
app.Math.F4.LabelsPosition = labelsposition ' set position of labels
app.Math.F4.LabelsText = "X1" & "," & "X2" ' set text of labels
OutResult.VerticalResolution = 0.000000001 ' set fine resolution of measurement output (for example, picosecond timing resolution)
OutResult.VerticalUnits = "S" ' set horizontal units of measurement to be the same as the horizontal units of the input waveform (e.g. seconds)
OutResult.Value = x2_time_position - x1_time_position ' time constant is reported
app.Measure.P2.Operator.Value = (x2_vertical_position / x1_vertical_position)
app.measure.p1.alias="RC Time Constant"
app.measure.p2.alias="Y1/Y2 ratio"
app.measure.p3.alias="Y1/Y2 percent"
Published: 978-1-5090-1416-3/16/$31.00 ©2016 IEEE
Y1/Y2 ratio is computed with a “pushed” parameter constant value
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Convert Y1/Y2 to Ratio in Percent
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ISO10605:2001(E) RC time constant on inverted pulse
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Trend Plot Shows Data Log of RC Time Constant Values
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Application example:Voltages Referenced Below Battery Level
Battery Voltage Signal From Generator
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Method 1 to characterize voltage level: Runt Trigger on individual pulses
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Method 1 to characterize voltage level: Runt Trigger on individual pulses
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Method 2 to characterize voltage level: Gated Mean Measurement
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Method 2 to characterize voltage level: Gated Mean Measurement
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Method 2 to characterize voltage level: Gated Mean Measurement
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Method 2 to characterize voltage level: Gated Mean Measurement
Dropout and Interrupt TestingMethod 1 Runt / Glitch Triggering Can Also Be Used To Capture Dropouts and Interrupts
Monitor AC or DC voltage
line with oscilloscope during
EMC testing
Verify that dropout or
interrupt occurred, and that
device under test was
unaffected
Electrical Fast Transient (EFT)
Testing
Transient Testing
Pulse Characteristics
Capacitive load dump
Inductive kickback/spike (back EMF from motor turn off)
Measurement Needs
Capture Time – longer the better:
Relay bounce (ms to ms)
Transient time
ms (motor)
ns (FET switch)
Measure 50-100 MHz transient
10s capture = 2Mpts at 100 MHz Sample Rate
EFT Testing – Electrical Fast TransientMeasurement Steps
Pulse Characteristics
Trise = 5ns
Tfall = 50ns
Burst of many 5x50 pulses
Measurement Needs
Capture 2ms of burst
Measure one pulse, verify shape (rise, fall,
width)
Measure burst frequency (10-100 kHz)
Measure Capture time of burst packet (2ms)
Measure burst packet rate (300ms)
EFT Testing – Electrical Fast TransientMeasurement Statistics
All-instance measurements characterizes all
76 rise times and pulse widths in this EFT
burst. EFT bursts can be batch processed to
determine EFT pulse characteristics, burst
frequency, and packet rate (shown next).
Maximizing Acquisition Memory for Events
100 ns/div
Empty space Empty space
Event occupies 1%
of acquisition time
Maximizing Acquisition Memory for Events
Acquisition time
optimized for event
1 ns/div
Maximizing Acquisition Memory for Events
Mosaic of events is acquired while optimizing
acquisition memory, and displayed without
empty spaces between events
Maximizing Acquisition Memory for Events
Individual timestamps for each event listed with segment
acquisition time and intersegment time. This will
automatically measure the EFT burst packet rate.
Mosaic of events is acquired while optimizing
acquisition memory, and displayed without
empty spaces between events
EFT Testing – Electrical Fast TransientSequence Mode and Octal Grid
Sequenced acquisition
of 5 EFT bursts
FFT
Zoom of one
EFT pulse
Zoom of one
EFT pulse
Zoom of one
EFT pulse
Zoom of one
EFT burst
Zoom of EFT
pulses
Zoom of EFT
pulses
Individual EFT Pulses
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One EFT Burst - Acquired at 2.5 GS/s - note linear top of burst
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One EFT Burst - Acquired at 125 MS/s - note amplitude distortion at top of burst
Comparison of one EFT burst captured at 1.25 GS/s and 125 MS/s
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125 MS/s 2.5 GS/s
Effect of Sample Rate on EFT Pulse Capture Sampled at 100 MS/s vs. 1.25 GS/s
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100 MS/s 2.5 GS/s
Frequency measurement parameter measures only values in the range between 9kHz and 11kHz
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Negative width parameter calculates gap time with values in range
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EFT Rise Time With 0-Max Thresholds
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Note the difference between P2 Width (gap time) and P4 Width (EFT pulse width)
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EFT Max, Area, and Energy Calculations
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Electrical Fast Transient (EFT)
Debugging Techniques
Using Segmented Memory
20 EFT Bursts Captured Using Segmented Memory
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Inter-burst EFT Timestamps
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Inter-pulse EFT Timestamps:Individual EFT pulses in segmented memory
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Overlay And Waterfall Of EFT Pulses Verifies Correct EFT Pulse Shape Characteristics
Segmented Overlay And Waterfall Of EFT Pulses Highlights Anomalies Reveals Possible Bad Contact Within The Transient Simulator
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MIL-STD-461GDepartment of Defense
Requirements for the Control of Electromagnetic Interference
Characteristics of Subsystems and Equipment
MIL-STD-461G
• CS117 and CS118 are new with the G version of
the standard specification
• Applicable to a wide variety of DoD systems
• CS117: Lightning strike testing
• CS118: ESD testing
“This requirement is applicable to all aircraft safety-critical equipment
interconnecting cables, including complete power cables, and
individual high side power leads. It is also applicable to non-safety
critical equipment with interconnecting cables/electrical interfaces that
are part of or connected to equipment performing safety critical
functions. It may be applicable to aircraft equipment performing non-
safety critical functions when specified by the procuring activity. This
requirement applies to surface ship equipment which is located above
deck or has interconnecting cables which are routed above deck.”
MIL-STD-461G CS116 damped sinusoid measurement
MIL-STD-461G EMC level-at-pulse and half life measurements
MIL-STD-461G multiple stroke and multiple burst lightning strike test
Surge Test example computing Rise Time, Pulse Width, Maximum, Area, and Charge
EMC - Radiated Immunity Testing
Radiated Immunity Testing - Real Time Functional Performance EvaluationDeviation detection of a device under test (DUT) during exposure to a disturbance
Devices under test
are exposed to
electric fields high
enough to effect
operation of non-
shielded equipment.
Transmit and receive
antennas generate a
controlled electric field
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Functional state of the
DUT is output through
non-conductive fiber
optic cablesMechanical mode
tuner
RF-hardened fiber optic transmitters
Outside the reverberant chamber, oscilloscope masks test for acceptance criteria
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Optical receiver
and O/E converter
16 channels performing mask test criteria such as
signal high level, signal low level, frequency, duty
cycle, and other criteria fit within tolerance limits
described in the test plan
Views from inside and outside of the reverberant chamber
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Simulated ECU (Electronic Control Unit) outputs:Two PWM outputs, a driver actuator signal, and a CAN split signal
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Mask testing ECU outputs: example with passing results
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Mask testing ECU outputs exceeding the tolerance mask criteria
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Special Thanks To:
Special thanks to Hitachi Automotive
Systems (an ISO accredited lab) for
providing access to EMC test setups,
equipment, expertise and insight.
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Questions?
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