Self Pre-Compliance Checklist Before an Emission Test

Booking a formal test lab costs money and schedule. A quick in-house pre-check with modest equipment greatly reduces the risk of a retest. Use this checklist to see that nothing is missed.

EUT configuration

• Confirm the same firmware, enclosure, cables and grounding as the final product.
• Connect real cables to every port and match representative cable lengths to the standard’s setup.
• Define the worst-case operating mode (highest clock, maximum load, all interfaces active) and write it in the test plan.

Instruments and settings

• Receiver settings: RBW 120 kHz for 30 MHz–1 GHz, peak detector for pre-scans, quasi-peak and average for final measurements.
• Use the latest calibration values for antenna factor, cable loss and preamp gain. (Calculators: cable-loss scaling, level budget)
• Confirm the receiver noise floor is at least 6 dB below the limit. (Calculator: noise floor)
• With stepped scans, check the step is at most half the RBW and that total time fits the schedule. (Calculator: stepped scan time)

Environment

• Save an ambient scan with the EUT off first. Knowing where broadcast and communication signals sit makes later interpretation easier.
• Check the measurement and antenna-to-EUT distance with a tape and photograph it.
• Keep the reflecting floor, nearby metal objects and cable layout constant.

Measurement procedure

• Pre-scan with the peak detector in both vertical and horizontal polarisation.
• Pick frequencies within 6 dB of the limit, maximise by antenna height and turntable angle, and measure finally with quasi-peak.
• For conducted emissions check both QP and average on each of the L and N lines.

Records and judgement

• Keep photos of the setup, cable layout, equipment list and settings, plus date and temperature/humidity.
• Tabulate the margin (limit − measured) per frequency and flag items under 3 dB as countermeasure candidates. (Calculator: limit margin)
• Agree beforehand how uncertainty is handled (direct comparison or guard band).