Tim, Here is the URL to Doug Smith's web page.
http://www.emcesd.com/ Regards, Ahmad Fallah -----Original Message----- From: Wan Juang Foo [mailto:f...@np.edu.sg] Sent: Sunday, April 21, 2002 11:47 PM To: am...@westin-emission.no; ieee pstc list Subject: Re: Decoupling - capacitor values Amund, Thanks for the info, not having a copy of the standard, may I out of curiosity ask about the measurement bandwidth for the various bands? The way I see it, I suppose you have to test Radiated Emission down to 150 kHz which is very unusual because it will bring you into the near field. The units given are in E field units so am I missing on something here. BTY I take it that the units given is 'dBuV/m' and not 'dBmV/m'. Back to the original question of decoupling capacitors values. If 100 pF as a quick fix, proves to do no good, and AFAIK in all probability it may not work for all kinds of reason, then you may have to sniff around to identify the 'radiating element'. This can be done without a chamber and your probes need not be calibrated if it is 'only' used for debugging. As I have mention earlier, train your browser search engine on Douglas Smith or DIY 1 GHz probe and you may get something useful. Does anyone out there have the URLs? sincerely Tim Foo amund@westin-emission. no To: "ieee pstc list" <emc-p...@ieee.org> Sent by: cc: (bcc: Wan Juang Foo/ece/staff/npnet) owner-emc-pstc@majordo Subject: SV: Decoupling - capacitor values mo.ieee.org 04/20/02 03:45 PM Please respond to amund Tim, The standard is IEC/EN60945:1997, "Maritime navigation and radio communication equipment and systems - General requirements- Methods of testing and required test results". Almost all ship classification societies as Lloyd's Register (LR), Germanischer Lloyd (GL), American Bureau of Shipping (ABS), Bureau Veritas (BV), Det Norske Veritas (DNV), Registro Italiano Navale (RINA), Korean Register of Shipping (KR), China Classification Society (CCS) refer to IEC60945. The limits are: 150kHz-300kHz 80-52dBmV/m 300kHz - 30MHz 52-34dBmV/m 30M - 156MHz 54dBmV/m 156M -165MHz 24dBmV/m 165M - 1000MHz 54dBmV/m The 156M -165MHz band is used for marine radio communication, what's why they have stringent demands on radiated emission. Amund -----Opprinnelig melding----- Fra: Wan Juang Foo [mailto:f...@np.edu.sg] Sendt: 20. april 2002 06:30 Til: am...@westin-emission.no Kopi: ieee pstc list Emne: Re: Decoupling - capacitor values Amund, Cortland may be right, a chamber 'may not' be needed, high ambient considerations to be put aside for the moment, even if the emission is measured to be on the " 24dBuV/m @ 3m, freq.band 155MHz-165MHz". I am just curious, what are the limits (or standards) are you trying to meet? From what I read here, is it CISPR22 (or EN 55022) or something like that (Class B) scaled back to 3 m? I note that it is about 20dB below FCC limits for class B (at 3m). If it is a single frequency line emission you can use a home made E or H field probe and work in the near field. Douglas Smith (who post frequently in this forum) have some good articles on DIY 1Ghz probes. You would need a E-field probe to 'sniff' out the CM portion of the emission and a H-field 'loop' to sniff out the offending loop before you can hug a 'return wire' to the offending signal line to cut the return loop down to size. I like to use the (thinisy, i.e. small gauge) wire-wraping wires for this. Good luck and hope that EMC don't always meant that it lead to Even More Coffee for the all nighter. Tim Foo Cortland Richmond <72146.373@compuserve. To: "am...@westin-emission.no" <am...@westin-emission.no>, ieee pstc com> list <emc-p...@ieee.org> Sent by: cc: (bcc: Wan Juang Foo/ece/staff/npnet) owner-emc-pstc@majordo Subject: Decoupling - capacitor values (ESR, layout, CM filter) mo.ieee.org 04/20/02 05:39 AM Please respond to Cortland Richmond Cortland Richmond <72146....@compuserve.com> 04/20/02 05:39 AM Amund, You do not HAVE to be in a chamber to keep working on this. Since there is only one Vcc pin (which processor IS this? - be SURE there is only one Vcc pin; you may have an unfiltered, unconnected Vcc pin or two) you are limited in how many capacitors you can attach to it. This doesn't matter; if you filtered power, and got 7 dB, you've done there what CAN be done there and should look look at other things. Troubleshoot the board. I too have thrown solutions at problems without knowing what exactly was wrong. It takes too long and costs too much. Find the source. A small 'scope probe, with the end taped over, makes a serviceable E-field probe. <snip> ------------------------------------------- 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"
