Hi If the timing involved is NTP, I'm not so sure that a normal home lan with gigabit switches would be a problem. You can indeed saturate the poor thing. Unless you have a very unusual system, it is unlikely you will saturate it for very long or saturate it very often. NTP is pretty tolerant of the occasional burp of a few ms.
Bob -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Attila Kinali Sent: Wednesday, May 23, 2012 11:10 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Serial port server .. any interest in a write up on using ? On Wed, 23 May 2012 01:54:20 -0700 Hal Murray <[email protected]> wrote: > > There aren't noticable more jitter for moderate (1-2 MByte/s) traffic. > > (Probably visible if i would do a statistical analysis...but..) > > 1-2 megabytes/sec is 8-16 megabits/sec. You won't get into serious troubles > until you saturate a link. With modern CPUs, it's trivial to saturate 100 > megabit links and not very hard to saturate 1 gigabit links. Yes, i know. I deliberately did not saturate the link. I know that it looks quite differently if i do and that jitter will rise into the ms range even on a local LAN. But anyone who does work with precision timing in such an enviroment is lost anyways. If you do timing over ethernet, you are well advised to use a seperate network that does not carry any other traffic, use fast, low latency, high bandwidth switches, etc pp... Ofcourse unless you go the way of IEEE1588, but then you're playing in a different league and probably have the money to buy a Cs clock or two :-) As for the problem of serial ports (to come back to the original topic), i'd probably use just a bunch of USB serial cables (the ones from Exsys work quite good) if i don't need any timing information. They are cheap, readily available, and if they have FTDI chip, they also work fine. For timing.. I don't know. But i guess a small PC with some RS232 cards in (there are even 4port cards for PCI-E available, and they are not expensive) would be more than enough for the needs i have. Anything else seems to me like either overkill, or not fitting to the problem description. Attila Kinali -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin _______________________________________________ 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.
