nanog mailing list archives
RE: CenturyLink
From: Matthew Huff <mhuff () ox com>
Date: Mon, 31 Dec 2018 09:52:47 +0000
There isn't a specific regulation on free-running GPS, just "due diligence". I work at a algorithmic program trading company (and have been for 20 years). We have a high ROI, the cost differential for the rubidium OC versus having to drop everything to conform to regulatory requirements due to a short GPS outage, makes this a no-brainer. ---- Matthew Huff | 1 Manhattanville Rd Director of Operations | Purchase, NY 10577 OTA Management LLC | Phone: 914-460-4039 -----Original Message----- From: NANOG [mailto:nanog-bounces () nanog org] On Behalf Of Saku Ytti Sent: Monday, December 31, 2018 3:28 AM To: Gary E. Miller <gem () rellim com> Cc: nanog () nanog org Subject: Re: CenturyLink Hey Gary, On Mon, 31 Dec 2018 at 05:02, Gary E. Miller <gem () rellim com> wrote:
The Rb frequency reference will be two or three orders of magnitude more stable than an expensive ovenized crystal.
Perhaps, but not supported by this: https://www.meinbergglobal.com/english/specs/gpsopt.htm For the tl;dr folk, crystal drifts +-4.5us per day, Rb +-1.1us (both seem like unsatisfactorily high numbers to me, i.e. you don't want to be free-running 24h with Rb). Luckily today we have GPS, Glonass, BeiDou, Galileo and couple smaller ones, so there should be somewhat reasonable amount of redundancy. Unsure which commercially available NTP or PPP master clocks support all four. But I of course readily accept Rb is objectively more accurate than crystal, I'm just curious where it matters and I'm curious which regulation applies, who fall under the regulation and what specifically does the regulation require about free-running accuracy. -- ++ytti
Current thread:
- RE: CenturyLink, (continued)
- RE: CenturyLink Matthew Huff (Dec 30)
- Re: CenturyLink Raymond Burkholder (Dec 29)
- Re: CenturyLink Shawn L via NANOG (Dec 30)
- Re: CenturyLink Mel Beckman (Dec 30)
- RE: CenturyLink Matthew Huff (Dec 30)
- Re: CenturyLink Saku Ytti (Dec 30)
- RE: CenturyLink Matthew Huff (Dec 30)
- Re: CenturyLink Saku Ytti (Dec 30)
- Re: CenturyLink Gary E. Miller (Dec 30)
- Re: CenturyLink Saku Ytti (Dec 31)
- RE: CenturyLink Matthew Huff (Dec 31)
- Re: CenturyLink Saku Ytti (Dec 31)
- Re: CenturyLink Luke Guillory (Dec 30)
- Re: CenturyLink Rubens Kuhl (Dec 29)