Yes - that's exactly what you should observe. Be careful, though, that you TDR from both ends - sometimes a transmission line's impedance will actually vary along its length, mimicking the effects of loss. If you TDR from both ends, you should always see the voltage going up as time increases. If you see the voltage going down when TDR'ed in one direction, you may be seeing actual impedance variation on that trace. As you infer, the amount of rise will vary with the rise-time, since some losses (the dominant ones at 26ps) are frequency-dependent. A TDT would show a significant increase in the risetime. Jeff Loyer -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Suresh Subramaniam Sent: Friday, November 21, 2003 2:01 PM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] TDR and line losses If I TDR (rise time 26ps) a long lossy transmission line, should I expect the impedance profile to gradually creep up to a higher value (assuming I start out with a 50 Ohm impedance?). In other words, how does the TDR take into account the effect of losses? Thanks Suresh ------------------------------------------------------------------ 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.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=20 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 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