EMC FLEX BLOG A site dedicated to Automotive EMC Testing for Electronic Modules

CISPR 25 Conducted Emissions - Current Method - MU Sources

CISPR 25 Conducted Emissions - Voltage - MU Sources 

CISPR 25 Radiated Emissions - ALSE Method - MU Sources

CISPR 25 RF EMISSIONS INPUT QUANTITIES - PROBABILITY DISTRIBUTION FUNCTION

CISPR 25:2021

 Measurement Uncertainty Budget is not a requirement imposed by any of the automotive EMC specifications and their approved report
templates. Not all international standards behind EMC Test Methods mention the Uncertainty Budget for outlined test equipment configuration.
The OEM EMC specs are asking the use of specific test equipment approved by them and in some instances designed by them.

Christian Rosu, 2023-04-02

Automotive EMC/Electrical testing specs like GM3097:2019, GMW3172:2022, FMC1278:2021, FMC1279:2021, CS0054:2018,
VW80000:2021 do not mention Measurement Uncertainty as requirement for reports.

CISPR 25:2021 includes INFORMATIVE Measurement Uncertainty but this is not a requirement for CISPR 25 compliant reports.

4.1.5 Test report
The report shall contain the information agreed upon by the customer and the supplier, e.g.
• sample identification,
• date and time of test,
• bandwidth,
• step size,
• required test limit,
• ambient data and test data.
Annex L (informative) Measurement instrumentation uncertainty – Emissions from components/modules – Test methods.
Annex M (informative) Uncertainty budgets for emissions from components/modules.

ISO 7637-2:2021 - no reference to Measurement Uncertainty.
ISO 7637-3:2016 - no reference to Measurement Uncertainty.
ISO 16750-2:2012 - no reference to Measurement Uncertainty.
ISO 16750-1:2018 - no reference to Measurement Uncertainty.

ISO 11452-2:2019 - no reference to Measurement Uncertainty.
ISO 11452-4:2020 - no reference to Measurement Uncertainty.
ISO 11452-8:2015 - no reference to Measurement Uncertainty.
ISO 11452-9:2012 - no reference to Measurement Uncertainty.
1SO 10605:2008 - no reference to Measurement Uncertainty.

Measurement Uncertainty is not a requirement for automotive electronic standards, nor a requirement of the vehicle OEMs. Measurement
Uncertainty is already included in the test levels (e.g. RE Limit Lines or RI Severity Level) for the automotive standards. These the limits are not affected by the measurement uncertainty budget generated by the laboratory for each test.

In the Commercial Electronics world (FCC & CE Mark), the Measurement Uncertainty is included in the report. This is because these
Commercial Standards require that a certain measurement uncertainty be achieved in order to apply the specified limits. If the lab's
measurement uncertainty doesn't meet the minimum requirements, then the limits must be adjusted based upon the lab's measurement
uncertainty calculations. However, this is not the case in the Automotive Industry.

Christian Rosu (Apr 2, 2023)

Automotive EMC/Electrical testing specs like GM3097:2019, GMW3172:2022, FMC1278:2021, FMC1279:2021, CS0054:2018,
VW80000:2021 do not mention Measurement Uncertainty as requirement for reports.

CISPR 25:2021 includes INFORMATIVE Measurement Uncertainty but this is not a requirement for CISPR 25 compliant reports.

4.1.5 Test report
The report shall contain the information agreed upon by the customer and the supplier, e.g.
• sample identification,
• date and time of test,
• bandwidth,
• step size,
• required test limit,
• ambient data and test data.
Annex L (informative) Measurement instrumentation uncertainty – Emissions from components/modules – Test methods.
Annex M (informative) Uncertainty budgets for emissions from components/modules.

ISO 7637-2:2021 - no reference to Measurement Uncertainty.
ISO 7637-3:2016 - no reference to Measurement Uncertainty.
ISO 16750-2:2012 - no reference to Measurement Uncertainty.
ISO 16750-1:2018 - no reference to Measurement Uncertainty.

ISO 11452-2:2019 - no reference to Measurement Uncertainty.
ISO 11452-4:2020 - no reference to Measurement Uncertainty.
ISO 11452-8:2015 - no reference to Measurement Uncertainty.
ISO 11452-9:2012 - no reference to Measurement Uncertainty.
1SO 10605:2008 - no reference to Measurement Uncertainty.

Measurement Uncertainty is not a requirement for automotive electronic standards, nor a requirement of the vehicle OEMs. Measurement
Uncertainty is already included in the test levels (e.g. RE Limit Lines or RI Severity Level) for the automotive standards. These the limits are not affected by the measurement uncertainty budget generated by the laboratory for each test.

In the Commercial Electronics world (FCC & CE Mark), the Measurement Uncertainty is included in the report. This is because these
Commercial Standards require that a certain measurement uncertainty be achieved in order to apply the specified limits. If the lab's
measurement uncertainty doesn't meet the minimum requirements, then the limits must be adjusted based upon the lab's measurement
uncertainty calculations. However, this is not the case in the Automotive Industry.

Christian Rosu (Apr 2, 2023)

AN (Artificial Network) or LISN (Line Impedance Stabilization Networks) must be periodically verified for integrity and performance.

CISPR 25 CONDUCTED EMISSIONS VOLTAGE METHOD SYSTEM CHARACTERIZATION

• Input a 100 MHz 50 dBμV signal to the DUT side of a LISN with the Power Supply Side terminated with a 50 OHM load;
• Measure via the voltage output of the LISN using the standard software that is used when testing that incorporates cable loss.
• The measurement must be within +/- 1.5 dBμV of the 50 dBμV input signal at 100 MHz.

• Use a Comb Generator (i.e., CG-515) with AN as noise source (1MHz Step).
• Terminate the Comb Generator with 40 dB attenuator.
• Measure from 0.15 to 200 MHz.

(1) Turn off Comb Generator for Ambient measurement.

(2) Turn on Comb Generator for data collection.

Christian Rosu

REF: AEMCLRP:2006