CISPR 25 (automotive), CISPR 32 (multimedia), CISPR 11 (industrial/scientific/medical), and a wide range of other product-family emissions standards all cite limit lines and pass/fail thresholds — but none of those standards define how to actually take a valid measurement. That foundational work is done by CISPR 16, the multi-part standard specifying the receivers, detectors, coupling devices, and test sites that every other CISPR emissions standard assumes as its measurement basis.
CISPR 16's Multi-Part Structure
| Part | Covers |
|---|---|
| 16-1-1 | The measuring (EMI) receiver itself — detector types, bandwidths, accuracy, pulse response |
| 16-1-2 | Coupling devices for conducted disturbance — LISNs/AMNs, current and voltage probes, CDNs |
| 16-1-3 | Ancillary equipment, disturbance power — the absorbing clamp and its calibration |
| 16-1-4 | Antennas and test sites for radiated disturbance |
| 16-1-5 | Antenna calibration sites and reference test site validation |
| 16-2-x | Measurement methods |
| 16-4 | Statistical methods, uncertainty, and measurement instrumentation confirmation |
The Detector Types — Why They Matter More Than People Expect
Peak detector captures the true peak amplitude of a signal, regardless of how often that signal repeats.
Quasi-peak (QP) detector weights a signal according to its repetition rate, using defined charge and discharge time constants.
Average detector indicates a value that rises roughly proportional to repetition rate.
RMS-average detector, a newer addition specified in CISPR 16-1-1, combines RMS detection above a defined corner frequency with average detection below it.
Why This Affects Equipment Selection
Most commercial emissions limit lines are published as quasi-peak limits, with a separate, lower average limit also frequently specified — meaning a genuinely CISPR-compliant EMI receiver needs to implement actual quasi-peak detection with the correct, standard-specified charge/discharge time constants.
The Frequency Band Structure
| Band | Frequency range (approximate) |
|---|---|
| Band A | 9 kHz – 150 kHz |
| Band B | 150 kHz – 30 MHz |
| Band C | 30 MHz – 300 MHz |
| Band D | 300 MHz – 1 GHz |
Antennas and Test Sites — CISPR 16-1-4
For radiated disturbance measurement specifically, CISPR 16-1-4 specifies the antenna types appropriate to different frequency ranges and the test site requirements — open area test sites (OATS) and semi-anechoic chambers — needed to produce valid, repeatable radiated measurements.
Practical Takeaway
CISPR 16 itself rarely appears as a standalone pass/fail requirement on a product — instead, it's the silent foundation underneath nearly every commercial emissions standard's actual limit line.