Dear All, The third thing I promised for this week... Some years ago, Darryl Veitch at U.Melbourne suggested to use the TSC register found in modern Pentium chips as a reference clock reference. The TSC register is related to the internal clock of the chip and very stable even when the chip is mounted inside a regular PC. Darryl and colleagues published a paper on the principle at IMC. If this works as expected, it will allow for a TTM setup without the need for a local GPS antenna. This will obviously make deployment a lot easier. The setup will require a stratum 1 NTP server a few hops away and there will be some loss of accuracy. All this will have to be quantified and calibrated. Over the last years, we have been trying to us this idea in TTM. Mark Santcroos worked on this while still at the NCC. When he left last year, the system worked but it had to be calibrated. This was to be done by the U.Melbourne. For various reasons, they only started on this in June this year. We now have a setup where the user can switch between standard GPS-based timestamping and TSC-based timestamping. We still have to add a switch and some code to the TTM software to do this for TTM. The idea is to do measurements with this setup in various circumstances, switching back and forth between timekeeping models, and compare the results. First results look good, but a lot of work still has to be done. The goal is to have this ready by RIPE53. Henk ------------------------------------------------------------------------------ Henk Uijterwaal Email: henk.uijterwaal(at)ripe.net RIPE Network Coordination Centre http://www.amsterdamned.org/~henk P.O.Box 10096 Singel 258 Phone: +31.20.5354414 1001 EB Amsterdam 1016 AB Amsterdam Fax: +31.20.5354445 The Netherlands The Netherlands Mobile: +31.6.55861746 ------------------------------------------------------------------------------