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Detectors Used in EMI Measurements
Average Detector
Average Detector
The average detector is required for some conducted emissions tests in conjunction
with using the quasi-peak detector. Also, radiated emissions measurements above 1
GHz are performed using average detection. The average detector output is always
less than or equal to peak detection.
Average detector operation
Average detection is similar in many respects to peak detection. The following
graphic shows a signal that has just passed through the IF and is about to be detected.
The output of the envelope detector is the modulation envelope. Peak detection
occurs when the post detection bandwidth is wider than the resolution bandwidth.
For average detection to take place, the peak detected signal must pass through a
filter whose bandwidth is much less than the resolution bandwidth. The filter
averages the higher frequency components, such as noise at the output of the
envelope detector.
Average detection response diagram
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