Advanced EMC measures: measurement challenges

Goals

formation-objectifs-seointro Advanced EMC measures: measurement challenges :

- Resolve EMC measurement difficulties in both the frequency and time domains

The aim of this training course is to:
- Gain in-depth knowledge of EMC measurement principles
- Understand and master sensors, transducers and antennas
- Be able to get the most out of measuring devices
- Understand and master the difficulties of time and frequency measurements
- Be able to accumulate experience in order to design and develop EMC measurement chains, control and verify them, and estimate measurement uncertainties

Program

1/ Introduction - Reminders

Units and acronyms

The decibel scale

Reminder on EMC measurement chains

Standardised validation tests and investigation tests

Software-controlled measurements and manual measurements

General information on transducers used in EMC

2/ Antenna transducers

Falstad Java applet: Electromagnetism, antennas and propagation

Reminder of antenna types

Active and passive antennas

Antenna parameters

Effect of measurement distance

Effect of polarisation

Coupled field/phase plane

Antenna parameters

Gain, directivity and equivalent area

Antenna factor

Transmission line antennas

Resonant cavity antennas

Frame or Van Veen antennas

E/H broadband field meter

E or H sensor/associated preamplifier

Near-field probes

E-field measurement problems

3/ Other transducers used in EMC

Principle of passive voltage probes and precautions

Principle of active voltage probes and precautions

Principle of differential voltage probes and precautions

Why measure currents rather than voltages

Principle of passive current probes and precautions

Principle of active current probes and precautions

Principle of Rogowski current probes

Principle of injection clamps and precautions

Use of RSIL as injection devices

Principle of mode-stirring Faraday cages

Measurement problems with current clamps

4/ Difficulties in time measurements

Principles to be observed

Bandwidth and waveform

Measuring a transition time

Sampling bandwidth

Sampling theorem

Very short pulse measurement

Signal-to-noise ratio after sampling

Distortion ratio: THD and FD

Floating voltage measurements

Fibre optic measurement chain

True RMS value

Problems with electrical measurements

Frequent errors in time analysis

5/ Difficulties in frequency measurements

Principles to follow

Distinguishing between analogue and FFT spectrum analysers

Relationships between FFT parameters

Principle of FFT spectrum analysers

Time windowing time windowing")

Choice of windowing for FFT analyses

Real-time FFT spectrum analyser

Analogue spectrum analysis of 1 MHz sinusoidal signals1 MHz

Analogue spectrum analysis of impulse signals

Low-frequency FFT analysis using a PC sound card SpectrumLab

Use of vector spectrum analysers

Use of the ‘SPAN 0’ function

‘Span 0’ for modulation control

Use of ‘Trigger’ features

Identification of microwave radiation using ‘Trigger’

Tracking generator and scalar network analyser

Adjustment of a tracking generator

Narrowband/wideband

CISPR detector responses: ‘Peak’, ‘QP’, “RMS”, ‘AVG’

Spectrum and spectral density

Noise coherence

Normalised RBW (IF BW)

Gaussian noise

Broadband noise measurement according to the detector

Spectral analysis simulations using LTSpice

Noise factor of spectrum analysers

Noise from two cascaded stages

Noise according to the detection mode

Phase noise

Transition from BE to LB disturbance

Repeated rectangular pulses

Repeated RF pulses

Filtering of ‘smoothing’ pulses by VBW

Post-detection filtering of impulse signals

Duration of a sweep according to the " dwell »

The 3 conduction modes

Signal resulting from the sum of 2 signals

Level error due to a weak signal (noise)

Frequent errors at the measurement receiver

Frequent errors at the spectrum analyser

Frequent errors in frequency analysis

6/ Immunity tests

Immunity tests in aeronautics according to DO160

Damped sine/cosine pulse

Lightning current aeronautical tests

Lightning components A, B and C

DO160 – 6 Lightning waveforms

Multiple bursts / multiple strokes

Transients induced according to D0160

Power supply immunity BF » immunity

Susceptibility to induced signals

Diode detector: Effect of amplitude modulation

Problems with broadband amplifiers

LTSpice simulation of BCI tests

Clamp immunity (BCI)

Reverberation chamber / shaker

TEM cell (Crawford)

Problems with immunity testing with RCD

Comparison of immunity 61000-4 3 / 61000-4 2

Problems with immunity testing

7/ Conclusions

Summary of useful websites

Summary of useful software

Bibliography



https://www.aemc.fr/wp-content/uploads/2021/01/Calendrier-AEMC-2021.pdf