Electronics World articles Popular Electronics articles QST articles Radio & TV News articles Radio-Craft articles Radio-Electronics articles Short Wave Craft articles Wireless World articles Google Search of RF Cafe website Sitemap Electronics Equations Mathematics Equations Equations physics Manufacturers & distributors Engineer Jobs LinkedIn Crosswords Engineering Humor Kirt's Cogitations RF Engineering Quizzes Notable Quotes Calculators Education Engineering Magazine Articles Engineering software RF Cafe Archives RF Cascade Workbook 2018 RF Symbols for Visio - Word Advertising Magazine Sponsor RF Cafe RF Electronics Symbols for Visio RF Electronics Symbols for Office Word RF Electronics Stencils for Visio Sponsor Links Saturday Evening Post NEETS EW Radar Handbook Microwave Museum About RF Cafe Aegis Power Systems Anritsu Alliance Test Equipment Amplifier Solutions Anatech Electronics Axiom Test Equipment Berkeley Nucleonics Centric RF Conduct RF Copper Mountain Technologies Empower RF everything RF Exodus Advanced Communications Innovative Power Products ISOTEC KR Filters Lotus Systems PCB Directory Rigol San Francisco Circuits Reactel RFCT TotalTemp Technologies Triad RF Systems Windfreak Technologies Withwave LadyBug Technologies Wireless Telecom Group Sponsorship Rates RF Cafe Software Resources Vintage Magazines Thank you for visiting RF Cafe!
Lotus Communication Systems Modular RF Component Building Blocks - RF Cafe

Quasi-Peak Detector Measurements

RF Cafe visitor Cris Schulze saw the Design News article I linked to titled, "EMI Emissions Testing: Peak, Quasi-Peak, and Average Measurements," and has given permission to reprint his brief response to it (originally posted on LinkedIn). The included notebook image includes an excerpt from Wikipedia's quasi-peak detector page, and he illustrates a block diagram of the test chain with de Forest's audion circuit that provides the fast rise-time and slow fall-time that characterizes it. A table of actual test data compares quasi-peak measurements to average measurements.

Quasi-peak Measurements (Cris Schulze, LinkedIn) - RF Cafe"Not really sure it is helpful, but I will share my technical understanding here. While the RMS is a measure of the real power, i.e. the equivalent thermal energy, of the signal, the peak value just describes the largest instant magnitude (the amplitude) within a certain time range - which makes it a bit difficult to measure. A bit more complicated is the quasi-peak measurement. The peak measurement tries to detect the highest value, even of very narrow pulses - which have quite low energy. But the pulse duration will have an effect to the disturbance of most systems, thus the peak value alone will be have little meaning to most real systems. Then the peak values will be formed, rectified to DC and integrated by a specified low-pass filter, thus the resulting "quasi-peak" value will be higher for wider pulses and smaller for shorter pulses. Then a quantitative value is generated which allows to compare the noise measurements of any system. Most important is the so called audion-circuit (named by Lee Deforest in 1906 - I think) which allows a quick charge and a slower discharge of a capacitor and significantly determines the deflection of the voltmeter connected to it. "

- Cris Schulze

  Director Technical Competence Center at TÜV Rheinland Japan Ltd.

References: CISPR (International Special Committee on Radio Interference )

Audion Circuit

Lee de Forest, U.S. 13,405A

Patented May 10, 1921




Posted August 10, 2018

Anritsu Test Equipment - RF Cafe
Axiom Test Equipment - RF Cafe
ConductRF Phased Matched RF Cables - RF Cafe
RF Electronics Shapes, Stencils for Office, Visio by RF Cafe
Innovative Power Products Passive RF Products - RF Cafe

Please Support RF Cafe by purchasing my  ridiculously low−priced products, all of which I created.

These Are Available for Free


About RF Cafe

Kirt Blattenberger - RF Cafe Webmaster

Copyright: 1996 - 2024


    Kirt Blattenberger,


RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while tying up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged.

My Hobby Website: