I just might have to try it and add it to the repertoire of troubleshooting techniques.
-----Original Message----- From: Gert Gremmen [mailto:g.grem...@cetest.nl] Sent: Thursday, August 22, 2002 1:06 PM To: Bill Morse; 'Cortland Richmond'; ieee pstc list Subject: RE: Emissions "quick test" The technique of temperature variation is that sensible, that heating up the *enclosure* of a small box by hand !!! will be easily audible , if the beat is down to only a 100 hz. Just tapping on the pcb will also be audible, not to let alone the effect of a freezing spray ! But you definitely need a BFO equipped (measuring) receiver. A spectrum analyser is of no use here (grin). This really is the fastest way of finding out the real source of a interfering spectral line. Note also that the difference between data/adress lines and R/W CE and Clcok emissions can easily be distinguished by the notable AM modulation (rythme) and using the speaker of your receiver it's easy to distinguish between foreign sources, (radio tv amateur cellular) and even other equipments (PC) in the neighbourhood. I even can distinguish between multiple processors on a large system. If your supply is not well stabilized, you will even hear the 100 (120) Hz hum on your spectral lines ! This technique in combination with your own ears is truly sensitive in a quality point of view: I have proposed in the past to use a measuring receiver for debugging purposes: a mal functioning microprocessor will definitely produce another sound then it's fully functioning brothers/sisters. You may astonish your collegues by fault debugging through walls !!! ;<)) Automated measuring systems are of no use outside the shielded room for exactly the lack of distinction between spectral lines, and those who work with a spectrum analyser do not know what they are missing... Gert Gremmen ce-test, qualified testing Gert Gremmen ce-test qualified testing. -----Original Message----- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Bill Morse Sent: donderdag 22 augustus 2002 19:01 To: 'Cortland Richmond'; Bill Morse; ieee pstc list Subject: RE: Emissions "quick test" Yep, they're many ways of doing it. Heating the crystals and watching the frequency of interest for variation, disabling the clocks one at a time, come to mind. They all have their uses and limitations. -----Original Message----- From: Cortland Richmond [mailto:72146....@compuserve.com] Sent: Wednesday, August 21, 2002 2:37 PM To: Bill Morse; ieee pstc list Subject: RE: Emissions "quick test" Just a note about telling clocks apart... unless they're phase locked (sometimes even then) a receiver with a BFO can let you distinguish from among clocks only 100's of Hz apart. Sometimes it can let you tell which of several clocks is slower to lock as well, as you can hear the varying tone that makes coming into lock with the reference. Cortland ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
