-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 My gut feeling would be that overall noise/power/length of run etc is going to be a significant factor, too - ie, longer runs or noisier power environments will have an impact.
As with all things sensitive, it's best to isolate things - I have yet to see any ethernet over powerline installations that couldn't be done with 30m of category 5 cable and 10 minutes with a drill (or lots of internal cable pins). Given that, my instinct would be to replace the ethernet over power boxes with real cables. Another upshot: You'll make any radio hams nearby very happy. Cheers, James On 10/02/2013 19:00, David wrote: > The poster is asking about ethernet over power line and not power > over ethernet. As you point out, the later should have zero effect > on ethernet latency. > > There are several ethernet over power standards. Latency will > include a bridge in each adapter, the effects of a noisy > uncontrolled AC power line when ARQ (automatic repeat query) is > used, and the TDMA or CSMA media access control system. > > I suspect varying power line conditions will have the largest > effect because any jitter from the media access control system will > be multiplied by ARQ. > > On Sun, 10 Feb 2013 08:14:38 -0800, Chris Albertson > <[email protected]> wrote: > >> THose power over Ethernet devices work with analog signals and >> don't evn look at the data packets. All they do is place a DC >> bias on the twisted pair. Ethernet is always transformer >> coupled so your routers, switches and computers never see DC. >> >> What is your NTP server using for a reference clock? I'd suspect >> that is the problem. If the reference is an Internet pool >> server than a few mS is about what you should expect. If using >> GPS then look to see if you have a good signal from enough >> satellites. >> >> But those POE boxes don't mess with the data packets, or at least >> the are not designed to do that. If one is broken it could be >> adding noise to the line. Broken hardware can do "anything". >> >> >> >> On Sun, Feb 10, 2013 at 3:18 AM, Rob Kimberley >> <[email protected]> wrote: >>> I'm not sure if this is the best place to ask the question, but >>> does anyone have experience of using Ethernet over power line >>> adapters? I have an outside office, and my router is in the >>> house plugged into the phone master socket. I have used two >>> Ethernet over power adapters, one at the router and one in the >>> office here to get internet access. The output of the adapter >>> then goes to a multi-port hub to give me Ethernet to all my >>> office devices including two Meinberg NTP servers. >>> >>> I've noticed large jitter readings on Meinberg's NTP monitor >>> program. Can be as low as 2ms, but much higher (50mS +), and >>> at this point NTP goes haywire. >>> >>> Not sure if it is the physical set up or something else. >>> >>> Any comments appreciated. >>> >>> Thanks. >>> >>> Rob > _______________________________________________ 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. > -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.17 (MingW32) iEYEARECAAYFAlEX9ncACgkQ22kkGnnJQAwcRACcC+nnF/iN4sPZ3S25FX4y7WRS VSEAn2fHeSA/4Ri6ZjJgdUek/y6xizGC =wM2v -----END PGP SIGNATURE----- _______________________________________________ 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.
