I forgot to answer the last part, about the detectors being filters. Properly speaking they are not, because they do not operate in the frequency domain. I think a better description is that they are weighting functions, which either exaggerate or de-emphasize a signal depending on its time domain characteristics.
---------- >From: "Ken Javor" <[email protected]> >To: Muriel Bittencourt de Liz <[email protected]>, Lista de EMC da IEEE <[email protected]> >Subject: Re: Detectors used in EMC testing >Date: Mon, Dec 4, 2000, 5:01 PM > > > > > ---------- >>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 >> >> ------------------------------------------- >> This message is from the IEEE EMC Society Product Safety >> Technical Committee emc-pstc discussion list. >> >> To cancel your subscription, send mail to: >> [email protected] >> with the single line: >> unsubscribe emc-pstc >> >> For help, send mail to the list administrators: >> Jim Bacher: [email protected] >> Michael Garretson: [email protected] >> >> For policy questions, send mail to: >> Richard Nute: [email protected] >> >> > > ------------------------------------------- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > To cancel your subscription, send mail to: > [email protected] > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Jim Bacher: [email protected] > Michael Garretson: [email protected] > > For policy questions, send mail to: > Richard Nute: [email protected] > > ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: [email protected] Michael Garretson: [email protected] For policy questions, send mail to: Richard Nute: [email protected]
