Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
PD CISPR TR 16 — Technical Reports for Radio Disturbance and Immunity Measuring Apparatus and Methods
Specification for Radio Disturbance and Immunity Measuring Apparatus and Methods — CISPR/TR 16 Technical Report Series (2004–2015)
📻 PD CISPR TR 16 is the BSI collection of technical reports (TR) issued by the International Special Committee on Radio Interference (CISPR), under the general title “Specification for radio disturbance and immunity measuring apparatus and methods”. While the main CISPR 16 family (IEC/CISPR 16-1, 16-2, etc.) specifies measuring instruments and methods, parts such as 16-4 appear as technical reports dealing with uncertainty, statistics, limit modelling and in-situ application guidance. The six documents in this UK implementation — 16-2-5, 16-3, 16-4-1, 16-4-3, 16-4-4 and 16-4-5 — are essential references for EMC laboratories, test houses and product developers carrying out disturbance (EMI) testing and conformity assessment. The UK adoption was handled by Subcommittee GEL/210/12 (EMC basic, generic and low-frequency phenomena) of Technical Committee GEL/210.
💡 CISPR 16 is the “metrology” of the EMC world. The technical reports here answer the question of how to measure credibly and how to set limits scientifically — correct citation in test reports is what makes a laboratory’s results reproducible and defensible.
1. Scope and Composition of the Series 📌
The PD CISPR TR 16 series comprises six published technical reports covering several critical facets of EMC measurement:
- 16-2-5:2008 (In-situ measurement): specifies how to measure the disturbing emissions of physically large equipment (large machines, complete installations) that cannot be brought into a standard test site, by measuring on site (in situ).
- 16-3:2010+A2:2015 (CISPR technical reports): a compilation of CISPR technical reports on measuring apparatus and methods for background and interpretation.
- 16-4-1:2009 (Uncertainty): systematically treats the sources, evaluation and expression of uncertainty in standardised EMC tests.
- 16-4-3:2004 (Statistics and limit modelling): statistical considerations and limit modelling for conformity decisions.
- 16-4-4:2007 (Complaint statistics): builds compliance models from complaint statistics.
- 16-4-5:2006+A1:2014 (Alternative test methods): conditions and requirements for using alternative test methods.
⚠️ Parts 16-4-3 and 16-4-4 are based on scanned copies; descriptions of those parts in this article are written from publicly available domain knowledge. For formulas, tables and procedures always confirm the current official BSI/IEC edition.
2. Technical Essentials of the Parts 🔧
| Part | Subject | Technical Highlights |
|---|---|---|
| 16-2-5 | In-situ measurement of large equipment | Far-field formula applicability for large EUT; Rayleigh distance criterion; boundary Dmeas > 2·Dsource²/λ |
| 16-3 | CISPR technical reports compilation | Compilation of technical notes; updated 3.2 and new 4.11 in 2012; A2:2015 revision |
| 16-4-1 | Uncertainty in standardised EMC tests | Types of uncertainty in emission measurement, source categories, influence quantities, evaluation and reporting |
| 16-4-3 | Statistics and limit modelling | Statistical thinking in limit setting; sample vs. population conformance |
| 16-4-4 | Complaint statistics and conformance | Modelling equipment conformance from field complaint data |
| 16-4-5 | Use of alternative test methods | Qualifying conditions for alternative methods (numerical, non-standard sites); A1:2014 update |
3. Key Technical Requirements 🔥
At the engineering level, the series lifts “measurement” from a simple reading to a credible metrological activity. The key requirements are:
- Far-field condition and Rayleigh distance: 16-2-5 makes clear that for a large EUT, the far-field extrapolation of equation (1) applies only when Dmeas is in the far field — the phase difference between centre and edge of the EUT is less than π/8 rad (22.5°), the boundary being the Rayleigh distance. Then Dmeas > 2·Dsource²/λ, where Dsource is the largest dimension between synchronous noise sources in the EUT (metres) and λ = 300/f(MHz). When only a small Dsource is identified, Dsource = 0.28λ is used so that measurement only lies in the region where the far-field component exceeds the reactive near field (Dmeas > λ/2π).
- Uncertainty evaluation: 16-4-1 classifies uncertainty types and sources in emission measurement and requires test houses to calculate and report combined standard uncertainty and expanded uncertainty as a basis for conformity decisions.
- Limit modelling statistics: 16-4-3 and 16-4-4 introduce statistical inference into conformance evaluation, showing why limit setting must consider both the emission distribution of the equipment population and the measurement uncertainty and complaint probability — a methodology of “statistics-based conformance”.
- Alternative method qualification: 16-4-5 sets the conditions, verification procedures and uncertainty requirements for using alternative test methods when standard methods are impossible.
🚨 The most common disputes in EMC reports centre on whether the measurement is credible. Extrapolation that ignores the far-field condition, conformance decisions without uncertainty, and unverified alternative methods all strip a test conclusion of its traceability and legal weight.
4. Engineering Practice and Application 🛠️
- 🔍 On-site acceptance of large equipment: for very large EUTs such as wind turbines, large machine tools and converters, use the in-situ method (16-2-5) at the installation site and judge extrapolation validity strictly by the Rayleigh distance criterion.
- 🔧 Laboratory quality system: integrate the 16-4-1 uncertainty evaluation into the laboratory quality manual and update uncertainty budgets periodically to satisfy ISO/IEC 17025 reporting requirements.
- 📊 Conformance and dispute handling: use the 16-4-3/16-4-4 statistical model to explain the assessment of “borderline samples” in a batch and to resolve customer objections to limit conformance.
- 📋 Documenting alternatives: under non-standard conditions, prepare an alternative method description, verification record and uncertainty evaluation per 16-4-5 so that any method change remains traceable.
5. Frequently Asked Questions ❓
❓ Q: What is the difference between CISPR 16 standards and CISPR 16 technical reports?
A: CISPR 16-1/16-2 are normative standards that set mandatory requirements for instruments and methods; CISPR TR 16 technical reports are explanatory and guiding documents clarifying uncertainty, statistics and modelling — “how to understand and apply” the standards. Together they form the complete measurement system.
A: CISPR 16-1/16-2 are normative standards that set mandatory requirements for instruments and methods; CISPR TR 16 technical reports are explanatory and guiding documents clarifying uncertainty, statistics and modelling — “how to understand and apply” the standards. Together they form the complete measurement system.
❓ Q: Why can’t large equipment simply be measured at the standard distance?
A: Standard distances and sites are designed for small- and medium-sized EUTs. When the equipment is physically large, the receive point may fall in the near field and direct extrapolation introduces large errors. 16-2-5 uses the Rayleigh distance and the 2·Dsource²/λ criterion to bound the formula’s applicability.
A: Standard distances and sites are designed for small- and medium-sized EUTs. When the equipment is physically large, the receive point may fall in the near field and direct extrapolation introduces large errors. 16-2-5 uses the Rayleigh distance and the 2·Dsource²/λ criterion to bound the formula’s applicability.
❓ Q: Can measurement uncertainty change a pass/fail conclusion?
A: Yes. The accepted practice compares the measured value together with the expanded uncertainty against the limit; if the uncertainty interval straddles the limit, the sample is judged “not confirmed compliant” or retested on a larger sample, as laid out in 16-4-1.
A: Yes. The accepted practice compares the measured value together with the expanded uncertainty against the limit; if the uncertainty interval straddles the limit, the sample is judged “not confirmed compliant” or retested on a larger sample, as laid out in 16-4-1.
🔍 Q: When is an “alternative test method” legitimately usable?
A: Only where the standard method is objectively impossible (equipment too large, site constraints, inadequate shielded environment) and the alternative has been verified, its uncertainty evaluated and recorded (16-4-5). It must never be substituted merely for convenience.
A: Only where the standard method is objectively impossible (equipment too large, site constraints, inadequate shielded environment) and the alternative has been verified, its uncertainty evaluated and recorded (16-4-5). It must never be substituted merely for convenience.