Hi In a real network you may have multiple switches and a lot of variable traffic. Your noise is coming from many sources. You make some high level choices in terms of sample rate. Without pretty exact information, you are going to have a hard time coming up with a useful answer.
Data with box A plugged directly and only into box B is much of what's out there. It only tells a small part of the story, and often it's a bit hard to work out exactly what is being shown. The practical answer is - this is one of the last things you will set. You get a working network up and then see what you are getting. Beat it up with real traffic and see what it does. Loop through adjust and observe. The alternate solution - let the local sources generate the phase noise inside your mask. Make the PLL very narrow (<< 1Hz) so it's outside the mask. Bob -----Original Message----- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Caudle Sent: Wednesday, March 02, 2011 9:55 PM To: time-nuts@febo.com Subject: [time-nuts] worst case jitter of PTP (IEEE1588) derived clock? Has anyone found reference which derives the worst case clock jumps to expect when using PTP (IEEE1588-2008) and how to derive a phase noise spectrum from that? I'm looking at a protocol which uses 1588-2008 to create a common clock between networked devices, and those devices are supposed to derive other clocks (e.g. sampling clocks) synchronized to the 1588 clock. If you are locking a sampling clock to that, you will need to know the worst case phase noise so you can design the PLL bandwidth, etc. So far haven't found the right reference which derives that, just some very gross maximum offset type of numbers, nothing which shows whether you might go +/- maximum offset in one cycle, or whether it drifts slowly to that level of offset, etc. I don't recall seeing much about PTP (Precision Time Protocol) on the list, compared to NTP. Are many people using it yet? -- Chris Caudle _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.