Perhaps it needs to be better than a millisecond. I remember an NTP accuracy of 100 microseconds, after enough round-trip time statistics were gathered. Perhaps the net is noisier now, and more uncertain. That certainly characterizes the messages carried by the 'net.
In any event, the noise from the frequency standards should be at least a factor of ten smaller than the filtered noise limit of the Internet, IMHO. Bill Hawkins -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of M. Warner Losh Sent: Saturday, January 14, 2006 11:54 AM To: [email protected]; [EMAIL PROTECTED] Cc: [EMAIL PROTECTED] Subject: Re: [time-nuts] NTP stratum 0 In message: <[EMAIL PROTECTED]> Neal McBurnett <[EMAIL PROTECTED]> writes: : On Sat, Jan 14, 2006 at 05:25:04PM +0100, TwoSpades wrote: : > I would like to know where could I find the FORMAL specification of the NTP : > stratum 0. : > I often read that it can be a GPS receiver, but I think that there must be a : > formal definition : > of the characteristics of that device. Well, it depends on what you mean by formal. The 'rough and ready' definition for stratum 1 time servers is that they are synchronized to a time source better than they would get from another ntp server. If your system time can be synchronized to within a few tens of microseconds with the receiver you have, then you are definitely stratum 1 material. If you relax the requirement to be only as good as you need to be to serve time over the internet, then I'd say that requirement drops to about 1ms. In general, you want the server to be traceable back to the official time, as produced by some time authority. For a simple ntp server, that tracking doesn't have to be too precise, from a time geeks point of view. If you are within about a millisecond, then no one will notice if the time exchange is over the internet... Warner _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
