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CISPR 25 (Section 6.3 & 6.4) RF Conducted Emissions Testing 

Overview of CISPR 25 Standard 

CISPR 25 is the global standard for testing conducted and radiated RF emissions in automotive electronics, covering vehicles, boats, and engines. The latest version, CISPR 25:2021, sets emissions limits and test procedures across a frequency range of 150 kHz to 5925 MHz. Its primary goal is to prevent interference with on-board receivers and ensure reliable vehicle operation. 

Sections 6.3 and 6.4 outline conducted emissions testing on power and signal leads using two methods: the voltage method with an artificial network (AN or LISN), and the current probe method, which measures RF currents along cables. 

Both methods require a compliant test setup, including a measuring receiver, ground plane, shielded enclosure, and proper equipment, to ensure accurate and repeatable results. 

CISPR 25 is widely adopted for emissions testing in passenger cars, commercial vehicles, and electric vehicles. It also defines performance classes that specify emissions limits, agreed upon by the purchaser and supplier, and documented in the test plan. 

Importance of RF Conducted Emissions Testing 

RF and conducted emissions testing are essential to prevent automotive electronics from interfering with communication, navigation, and infotainment systems. As vehicles incorporate more wireless technology, even minor emissions from power or signal leads can affect performance. 

CISPR 25 provides clear procedures to detect and resolve these issues early in development. This is especially critical for infotainment systems, sensors, and control modules. 

The standard’s frequency range (150 kHz to 108 MHz) focuses on high-risk bands such as AM/FM radio and GPS. It ensures components meet OEM and regulatory EMC requirements by preventing disruption to on-board receivers. 

CISPR 25 supports risk management through systematic testing and documentation, helping manufacturers avoid recalls and warranty claims. Its emissions limits and performance classes also provide a clear framework for certification and communication with OEMs. 

Ultimately, RF emissions testing ensures reliable, interference-free operation of vehicle electronics in real-world environments. 

Key Features and Benefits of CISPR 25 Testing 

CISPR 25 is essential for validating RF emissions from automotive electronics. It defines two main methods for conducted emissions testing: the voltage method using an artificial network (LISN) for power leads, and the current probe method for signal leads. 

The standard requires a compliant test setup, including a ground plane, shielded enclosure, artificial mains network, and a CISPR 16-1-1 measuring receiver. Tests cover the 150 kHz to 108 MHz range, using double-shielded coaxial cables to minimize interference. 

CISPR 25 also specifies harness layout, current probe placement, and calibration procedures to ensure accurate, repeatable results. Its detailed reporting supports traceability and continuous design improvement. 

By following the standard, manufacturers ensure supply line emissions compliance, streamline certification, and build confidence with OEMs and customers. 

Risk Management and the Role of Testing 

Risk management is a key benefit of CISPR 25 emissions testing. By identifying emissions early, engineers can address issues before they impact vehicle performance or customer satisfaction. The standard’s procedures and performance classes provide a solid framework for benchmarking and improvement. 

CISPR 25 is especially important for powertrain, commercial, and electric vehicles, where managing emissions risks is critical as electrification and connectivity increase. Its detailed setup and calibration requirements ensure accurate, repeatable measurements. 

Covering both power and signal leads, CISPR 25 addresses all emission sources. Integrating this testing into development helps manufacturers reduce recalls, warranty claims, and reputational risks while fostering innovation and market leadership. 

Why Choose CISPR 25 for RF Conducted Emissions Testing? 

CISPR 25 is the industry standard for RF and conducted emissions testing in automotive electronics. Its comprehensive procedures and emission limits are recognized worldwide by OEMs and regulators. The standard evaluates emissions using voltage measurements for power leads and current probes for signal leads. 

A standardized test setup—including an artificial network, current probe, ground plane, and shielded enclosure—ensures consistent, comparable results across labs and products. Its defined frequency range and limits support compliance for passenger and commercial vehicles. 

CISPR 25 also streamlines emissions data analysis and reporting, simplifying compliance documentation and certification. It adapts to modern technologies like electric vehicles and advanced infotainment systems. 

By adopting CISPR 25, manufacturers can accelerate product development, reduce time to market, and ensure reliable performance in complex automotive EMC environments. 

How to Conduct CISPR 25 Conducted Emissions Testing 

Pre-Testing Preparation 

  • Review the CISPR 25:2021 Edition 5.0 standard and determine the appropriate performance class for the product. 
  • Select the measurement method: voltage method for power leads (using artificial network/LISN) or current probe method for signal leads. 
  • Prepare the test setup, including: 
  • Shielded test enclosure or ALSE 
  • Ground plane CISPR 25 compliant 
  • Artificial mains network (AN/LISN) 
  • CISPR 25 current probe (if using the current method) 
  • Measuring receiver CISPR 25 compliant (EMI receiver or spectrum analyzer) 
  • High-quality double-shielded coaxial RF cables 

Testing Procedures 

Voltage Method (Section 6.3) 

  • Connecting the EUT’s power leads to an artificial network. 
  • Use the measuring receiver to record conducted emissions voltage across the specified frequency range (150 kHz to 108 MHz). 
  • Compare results to the emissions limit table CISPR 25 for the relevant performance class. 
  • Document all test conditions, including supply voltage and test harness configuration. 

Current Probe Method (Section 6.4) 

  • Place the CISPR 25 current probe at a minimum of two locations along the signal leads. 
  • Use the measuring receiver to record RF current emissions over the specified frequency range. 
  • Ensure probe placement and calibration procedure for CISPR 25 are followed for accurate results. 
  • Compare measured emissions to the standard’s limits and document findings. 

Testing Report 

  • Include detailed diagrams of the test setup, including ground plane, artificial network, current probe, and measuring receiver. 
  • Record all emissions data, frequency ranges, and detector types used (peak, quasi-peak, average). 
  • Summarize compliance with CISPR 25 emissions limits and performance class. 
  • Provide calibration records and any deviations from the standard procedure. 

Industry Applications and Relevance 

CISPR 25 is essential for EMC compliance and emissions validation in automotive components and modules. It is widely used to test RF and conducted emissions in passenger cars, commercial vehicles, electric vehicles, and key systems like infotainment and sensors. 

The standard’s detailed methodology supports regulatory compliance and continuous improvement. Its precise requirements for test setup, frequency range, and emission limits ensure thorough evaluation and control of all emission sources. 

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