Re: [time-nuts] Using 5335 frequency counter for timing
On Sun, May 7, 2017, at 20:11, Hal Murray wrote: > kb...@n1k.org said: > > None of them will do as well as a really fast scope. > How accurate is the clock in a scope? Do the high end scopes have an > external clock input? My scope (Keysight MSOX3104, so 1 GHz) is rated at ±1.6 ppm (after a 30 minute warmup and ±10C from calibration temperature). The 3000 series and below don't have 10 MHz external reference inputs; I know the 4000 series does. /gp ___ 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.
Re: [time-nuts] Best Chance GPS module
On Thu, Dec 1, 2016, at 09:01 AM, Chris Albertson wrote: > The other thing you might look at is NOT using NTP but using PTP. This > might be a better match to your needs but it requires that you replace > all your network gear with equipment that can make hardware time stamps > on the network packets. You don't actually need to have PTP-capable network gear to make PTP work reasonably well. I have a small test environment with a Symmetricom S300-Rb PTP grandmaster distributing time to six Cisco UCS blades running FreeBSD. The S300 does hardware timestamping, but the UCS blades do not. The network has a Cisco UCS fabric switch plus an Arista 7124S, neither of which support PTP transparency. Works fine; I haven't measured it exhaustively, but preliminary data suggests that I am getting 2.5e-5 seconds of drift in the worst case. I've heard reports that full hardware timestamping and transparent switching can easily get you into the 1e-7 range, but I haven't tried that yet. /gp ___ 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.
Re: [time-nuts] Thinking outside the box a super reference
On Fri, Nov 4, 2016, at 02:27 PM, Poul-Henning Kamp wrote: > > In message <2af27ebe-9200-c348-c89b-b98f9c973...@karlquist.com>, "Richard > (Rick) Karlquist" w > rites: > >Also, one of the Rb isotopes is slightly radioactive. > >35 years ago, the guy in the next cubicle got away with > >storing it under his desk. He also happily smoked > >cigarettes all day at his desk. Another ERA. > Rb87 has a halflife north of the age of the planet as far > as I recall, and the result is a beta which goes nowhere > far and Sr87 which is stable. 87-Rb has a half life of something like 4.9e10 years — you'll be waiting a while for that strontium. /gp ___ 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.
