While it is possible to use an IA that has sufficient bandwidth to obtain apparent impedance at the test port, a TDR / TDT or VNA are the instruments of choice for evaluating transmission channels. Think of the IA as a poor man's1 port VNA. Steve Bharathkumar Raju wrote: > Dear All, > Is it possible to measure the impedance of USB D+ & D- signal traces > of an unassembled PCBA, using HP 4249 impedance analyser? One end of the > traces are left open and I measure the impedance across the pair at the other > end. By measuring Zsc & Zoc I hope we can calculate the CI. > Measuring with other end of the traces connected together (Zsc) seem > to be easy and we get consistant results. What are the issues in using HP > 4249 or similar impedance analysers in measuring impedance of open ended > untermintaed traces (Zoc)? I request the experts to guide me in measuring Zoc > accurately using impedance analysers. > Bharath > > > Chat on a cool, new interface. No download required. Go to > http://in.messenger.yahoo.com/webmessengerpromo.php > ------------------------------------------------------------------ > 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 technical documents are available at: > http://www.si-list.net > > 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 > > > > > -- Steve Weir Teraspeed Consulting Group LLC 121 North River Drive Narragansett, RI 02882 California office (408) 884-3985 Business (707) 780-1951 Fax Main office (401) 284-1827 Business (401) 284-1840 Fax Oregon office (503) 430-1065 Business (503) 430-1285 Fax http://www.teraspeed.com This e-mail contains proprietary and confidential intellectual property of Teraspeed Consulting Group LLC ------------------------------------------------------------------------------------------------------ Teraspeed(R) is the registered service mark of Teraspeed Consulting Group LLC ------------------------------------------------------------------ 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 technical documents are available at: http://www.si-list.net 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