----------
>From: Muriel Bittencourt de Liz <[email protected]>
>To: Lista de EMC da IEEE <[email protected]>
>Subject: Detectors used in EMC testing
>Date: Mon, Dec 4, 2000, 11:08 AM
>
>
> Hello Group,
SOME SIMPLE ANSWERS:
>
> I have a couple questions about detectors used in EMC testing, namely:
>
> - We use Peak, Quasi-Peak and Average detectors. What is the reason for
> using this three different detectors?
PEAK DETECTOR RETURNS THE SAME VALUE OF SIGNAL REGARDLESS OF REP RATE/DUTY
CYCLE OF SIGNAL.
QUASI-PEAK DETECTOR OUTPUT IS PROPORTIONAL TO INTERFERENCE VALUE, BASUCALLY
OUTPUT IS PROPORTIONAL TO BOTH AMPLITUDE AND REP RATE/DUTY CYCLE.
AVERAGE DETECTOR OUTPUT IS AVERAGE OF SIGNAL OVER AVERAGE FILTER TIME
CONSTANT.
>
> - What is the principle of operation of each one of the detectors? THE PEAK
DETECTOR HAS A FAST RISETIME AND SLOW DECAY; THE QUASI-PEAK DETECTOR HAS
SLOWER RESPONSE THAN PEAK DETECTOR, AND THERE ARE DIFFERENT QUASI-PEAK
PARAMETERS IN DIFFERENT FREQUENCY RANGES; THE AVERAGE DETECTOR HAS A SLOWER
TIME CONSTANT YET AND IN ORDER TO USE IT ACCURATELY YOU NEED TO BE IN
LINEAR, NOT LOG-AMPLIFIER MODE (I BELIEVE THIS IS ALSO TRUE FOR QUASI-PEAK
DETECTION).
>
> - When I make a DC test (equipment with DC feeding through the LISN),
> the three detectors are still needed? Why? THE DETECTOR HAS TO DO WITH THE
TYPE OF EMI STANDARD YOU ARE MEASURING TO, NOT THE TYPE OF POWER USED BY THE
EUT.
>
> - The Quasi-Peak and the Average detectors can be viewed as "filters"
> that reduce the EMI seen by the receiver?
>
> Thanks in advance for the help.
>
> Best Regards
>
> Muriel
>
> ==
> Muriel Bittencourt de Liz - EMC Engineer
> Group of Conception and Analysis of Electromagnetic Devices
> Federal University at Santa Catarina
> Florianópolis, Santa Catarina
> Brazil
>
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