ah ... now we know where the term "averaging mean" method comes from. Averaging refers to placing the TDR instrument into averaging mode. Mean refers to the segment of the TDR waveform over which the mean is measured. This method is reasonable, considering that most TDR coupon launches are terrible, and attempts to remove the launch artifacts from the measurement result. But, it is incorrect, and does not provide a measure of the actual impedance of the PCB trace. Scott McMorrow Teraspeed Consulting Group LLC 121 North River Drive Narragansett, RI 02882 (401) 284-1827 Business (401) 284-1840 Fax http://www.teraspeed.com Teraspeed® is the registered service mark of Teraspeed Consulting Group LLC Loyer, Jeff wrote: > One source for this kind of information: > > http://www.intel.com/design/chipsets/applnots/29817901.pdf=20 > > It's pretty old, though - much has been learned since 2000... > > Jeff Loyer > > > -----Original Message----- > From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] > On Behalf Of Ivor Bowden > Sent: Thursday, March 23, 2006 5:07 PM > To: si-list@xxxxxxxxxxxxx > Subject: [SI-LIST] Re: Q on TDR coupon measurements > > I've been enjoying the discussion on TDR measurements. While I > understand the principle, I don't have experience with them beside > evaluating TDR printouts. > > I was wondering if anyone knows a web site or other resource that has a > variety of example waveforms and their proper interpretations? Including > touching on some of the details Scott and Eric mention. > > tia, > > Ivor Bowden > Curtiss-Wright Controls Embedded Computing > > > ------------------------------------------------------------------ > To unsubscribe from si-list: > si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field > > or to administer your membership from a web page, go to: > //www.freelists.org/webpage/si-list > > For help: > si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field > > List FAQ wiki page is located at: > http://si-list.org/wiki/wiki.pl?Si-List_FAQ > > List technical documents are available at: > http://www.si-list.org > > List archives are viewable at: =20 > //www.freelists.org/archives/si-list > or at our remote archives: > http://groups.yahoo.com/group/si-list/messages > Old (prior to June 6, 2001) list archives are viewable at: > http://www.qsl.net/wb6tpu > =20 > ------------------------------------------------------------------ > To unsubscribe from si-list: > si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field > > or to administer your membership from a web page, go to: > //www.freelists.org/webpage/si-list > > For help: > si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field > > List FAQ wiki page is located at: > http://si-list.org/wiki/wiki.pl?Si-List_FAQ > > List technical documents are available at: > http://www.si-list.org > > List archives are viewable at: > //www.freelists.org/archives/si-list > or at our remote archives: > http://groups.yahoo.com/group/si-list/messages > Old (prior to June 6, 2001) list archives are viewable at: > http://www.qsl.net/wb6tpu > > > ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List FAQ wiki page is located at: http://si-list.org/wiki/wiki.pl?Si-List_FAQ List technical documents are available at: http://www.si-list.org List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu