Hi The other nice thing about TDR's is that the units come out in units of time. If you are working on a timing system, there's much less opportunity to goof things up by a conversion error.
Bob On Jan 25, 2013, at 6:37 PM, Magnus Danielson <[email protected]> wrote: > On 01/24/2013 03:52 PM, John Lofgren wrote: >>> Should I make it a habbit of TDRing my GPS antennas, receivers and >>> splitters? >>> >>> Cheers, >>> Magnus >> >> I think that question ties into some of the other responses to the original >> post. The value of doing the TDR measurement would probably depend on your >> cable lengths and how likely you think it is that a connector mismatch would >> cause cable reflections that might smear the GPS signals. >> >> Since you're fortunate enough to have a TDR, it might be interesting to do >> it just to see how much mismatch there really is. If the resolution of the >> measurement is good enough you should be able to see all of the connectors. >> If nothing else, it might tell you if you have a bad cable end or a loose >> connection. > > Electrical TDRs excel on short distances, as they have great time resolution, > but the dynamics isn't great. VNAs has great dynamics, but tend to lack the > time resolution. The high frequency losses of cabling does however make some > of the details go lost anyway, and it also kicks in for reflections. > Sufficiently lossy cables makes impedance mismatches less critical as the > reflection at the sink side would need to traverse the cable twice, as well > as being reflected at the source side. So low-loss cables also calls for > lower reflections (rather than impedance matching really) in order to achieve > the higher system performance. > > TDRing may not be the ultimate tool, but it is highly educative at least. :) > >> Maybe the Italian guys should have run an optical TDR on their timing setup >> before doing the neutrino measurements :) > > Actually, that would have meant that they where suspecting things from start. > Also, validating connections means unhooking them, allowing for human errors > on each location. > > Cheers, > Magnus > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
