Muriel, I once had access to a file that described the history behind adoption of the standard bandwidths and time constants. It was fascinating. However, I neglected to make a copy, and have not seen it for years.
Peak detectors are pretty well self explanatory. Whatever the peak signal is, it is retained for a time much longer than the repetition rate of any amplitude variation present. Average detectors respond to merely the average level of an incoming signal over time. the one most folks get tripped up on is Quasi-peak. These detectors specify time constants for charge and discharge of the detector filtering. The time constants are selected by reference to what kinds of signals cause the most noticeable interference. In determining this, as I recall, tests were made by having people listen to radio and watch television as the level, PRF and duty cycle of interfering signals were adjusted. Having a good idea which caused the most noticeable effects, the CISPR 16 committee devised combinations of filter bandwidths and detector response to preferentially accentuate interference of a bothersome kind, while de-emphasizing less bothersome interference. Perhaps we have people reading this list who took part in the formulation of CISPR 16. It is an interesting picture of the relationship between the "real world" of human beings, and the minutiae of our profession. Cortland ====================== Original Message Follows ==================== >> Date: 04-Dec-00 11:12:01 MsgID: 1077-7188 ToID: 72146,373 From: Muriel Bittencourt de Liz >INTERNET:[email protected] Subj: Detectors used in EMC testing Chrg: $0.00 Imp: Norm Sens: Std Receipt: No Parts: 1 List-Post: [email protected] Date: Mon, 04 Dec 2000 17:08:35 -0200 From: Muriel Bittencourt de Liz <[email protected]> Organization: GRUCAD Subject: Detectors used in EMC testing Reply-To: Muriel Bittencourt de Liz <[email protected]> Hello Group, 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? - What is the principle of operation of each one of the detectors? - When I make a DC test (equipment with DC feeding through the LISN), the three detectors are still needed? Why? - 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] ====================== End of Original Message ===================== ------------------------------------------- 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]
