The Conducted Emission Limits

Note The FCC does not state average limits, only quasi-peak. However, the FCC does accept certification to CISPR 22. But in that case, mix-and-match of the standards is not allowed — it s either one or the other. 

Returning to Table 9-1, we look at the CISPR Class B regions between 150 kHz to 450 kHz and 450 kHz to 500 kHz. Note that this is actually one continuous region, with the limit line passing straight from 150 kHz through 500 kHz ( straight on a standard dBp,V vs. log(f) plot). 

Example What are the CISPR Class B conducted emission limits at a frequency of 300 kHz  

The quasi-peak limit (which is defined to be 10 dB higher in this region) is automatically 60.25 dBfiV. 

Therefore, practically speaking, equipment compliant to CISPR will always be found compliant to FCC limits. 

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We observe that the conducted emissions limit lines (CISPR 22) actually allow for progressively higher emissions on our part — below 500 kHz. 

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