root@petro.UUCP (Petty System God) (12/28/90)
There have been several programs posted recently to allow one to have his system call the Naval Observatory clock and have the time set all without human intervention. Having decided that this is a good idea I coerced some code into working only to discover that there appears to be a discrepancy between the time reported by WWV and that reported by the dial up number at the Naval Observatory. The difference is about 12 seconds which I consider significant since both these guys are supposed to be time standards and should do better than my Timex. I noticed, after spending a couple of hours hacking code to call the Naval Observatory and set the clock, that the time reported by the Naval Observatory was not the time I expected. I was expecting something close to the drumming that WWV was producing in the corner but to my surprise the Naval Observatory was reporting time about 12 seconds behind WWV. To confirm the observation I called back the Naval Observatory with cu and let it report while WWV was reporting over the shortwave -- sure enough when WWV hit 124900 the Naval Observatory was reporting about 124848. OK, I give up, who's right ? ---- Gilbert B. Andreen - bruce@petro.UUCP cs.utexas.edu!swrinde!petro!bruce
bob@rel.mi.org (Bob Leffler) (12/29/90)
In article <63354@petro.UUCP> root@petro.UUCP (Petty System God) writes: >the Naval Observatory was reporting time about 12 seconds behind WWV. >To confirm the observation I called back the Naval Observatory with cu and >let it report while WWV was reporting over the shortwave -- sure enough when >WWV hit 124900 the Naval Observatory was reporting about 124848. My first guess for the difference is the delay intransmitting the data via the different transports. i.e. How long does it for the data to transmit through the numberous switches, land lines, satelites, etc to reach your modem? I'm sure that it is different than shortwave. bob -- Bob Leffler, (bob@rel.mi.org), (313) 696-2479 Opinions expressed Electronic Data Systems, GMC Truck SBU may not be those Box 7019, 5555 New King Street, Troy MI. 48007 of my employer.
allbery@NCoast.ORG (Brandon S. Allbery KB8JRR) (12/29/90)
As quoted from <69@rel.mi.org> by bob@rel.mi.org (Bob Leffler): +--------------- | In article <63354@petro.UUCP> root@petro.UUCP (Petty System God) writes: | >the Naval Observatory was reporting time about 12 seconds behind WWV. | | My first guess for the difference is the delay intransmitting the data via | the different transports. i.e. How long does it for the data to transmit | through the numberous switches, land lines, satelites, etc to reach your | modem? I'm sure that it is different than shortwave. +--------------- 12 seconds?! A phone call with that delay wouldn't be considered usable by most people. I suspect the problem lies somewhere else. ++Brandon -- Me: Brandon S. Allbery VHF/UHF: KB8JRR on 220, 2m, 440 Internet: allbery@NCoast.ORG Packet: KB8JRR @ WA8BXN America OnLine: KB8JRR AMPR: KB8JRR.AmPR.ORG [44.70.4.88] uunet!usenet.ins.cwru.edu!ncoast!allbery Delphi: ALLBERY
efb@SUNED1.NSWSES.NAVY.MIL (Everett F Batey II) (12/29/90)
Slow propagation times ARE NOT on the order of 12 seconds .. try modest fract- ions of distance/186000 mi X ( 1/3 .. 2/3 ) .. EVEN over MILNET .. worst case crossing country and forwarding packets 400 to 1200 milliseconds with lots of hosed forwarding .. /e/
poffen@sj.ate.slb.com (Russ Poffenberger) (01/01/91)
In article <69@rel.mi.org> bob@rel.mi.org (Bob Leffler) writes: >In article <63354@petro.UUCP> root@petro.UUCP (Petty System God) writes: >>the Naval Observatory was reporting time about 12 seconds behind WWV. >>To confirm the observation I called back the Naval Observatory with cu and >>let it report while WWV was reporting over the shortwave -- sure enough when >>WWV hit 124900 the Naval Observatory was reporting about 124848. > >My first guess for the difference is the delay intransmitting the data via >the different transports. i.e. How long does it for the data to transmit >through the numberous switches, land lines, satelites, etc to reach your >modem? I'm sure that it is different than shortwave. > >bob > Well, assuming that the signal (over the phone) travels at the speed of light (actually probably considerably less, maybe half), 12 seconds means about a million miles, even geo-stationary satellites are only 22,000 miles away, round trip is 44,000 miles. If I make long distance calls, especially overseas, there is a definite time lag, but nowhere near 12 seconds. Russ Poffenberger DOMAIN: poffen@sj.ate.slb.com Schlumberger Technologies UUCP: {uunet,decwrl,amdahl}!sjsca4!poffen 1601 Technology Drive CIS: 72401,276 San Jose, Ca. 95110 (408)437-5254
kianusch@unigold.UUCP (Kianusch Sayah Karadji) (01/01/91)
In article <69@rel.mi.org> bob@rel.mi.org (Bob Leffler) writes: >In article <63354@petro.UUCP> root@petro.UUCP (Petty System God) writes: >>the Naval Observatory was reporting time about 12 seconds behind WWV. >>[...] > >[...] i.e. How long does it for the data to transmit >through the numberous switches, land lines, satelites, etc to reach your >modem? I'm sure that it is different than shortwave. [...] That could be, but ... that wouldn't make a delay of 12 seconds. Kianusch
marc@kg6kf.AMPR.ORG (Marc de Groot) (01/02/91)
In article <69@rel.mi.org> bob@rel.mi.org (Bob Leffler) writes: [ stuff about WWV vs. Naval Observatory ] >My first guess for the difference is the delay intransmitting the data via >the different transports. i.e. How long does it for the data to transmit >through the numberous switches, land lines, satelites, etc to reach your >modem? I'm sure that it is different than shortwave. Last time I looked it up, the National Bureau of Standards claimed that time accuracy when TELEPHONING the WWV audio in Fort Collins, CO. was "not better than 30 milliseconds". It sounds to me like 12 seconds is not telephone network delay. Given a choice between WWV and the Naval Observatory, you should consider WWV to be more accurate. It would be interesting to find out why there's such a discrepancy. ^M -- Marc de Groot KG6KF | "The all-American boy prefers beauty Internet: marc@kg6kf.ampr.org | to brains because he can see better UUCP: uunet!hoptoad!noe!marc | than he can think." -Farrah Fawcett Packet radio: KG6KF @ K3MC |
manson@giza.cis.ohio-state.edu (Bob Manson) (01/02/91)
In article <713@noe.kg6kf.AMPR.ORG> marc@noe.UUCP (Marc de Groot) writes: >It would be interesting to find out why there's such a discrepancy. Three theories: a) The Naval Observatory is located in a vast tract of hyperspace located approximately 12 light-seconds from the Earth. This was done in order to make clearer observations of celestial phenomena. b) They're in their own time zone, or they're trying to claim they THEY know what time it is and nobody else does. Or compensating for something-or-other. c) Bill and Ted haven't set the clock yet, or they're setting it by calling up the Time & Temp service. My guess would be c), but I suspect there is some saner explanation. Bob manson@cis.ohio-state.edu
bruce@THINK.COM (Bruce Walker) (01/03/91)
Date: 2 Jan 91 03:15:50 GMT From: att!pacbell.com!pacbell!kg6kf!marc@ucbvax.Berkeley.EDU (Marc de Groot) Given a choice between WWV and the Naval Observatory, you should consider WWV to be more accurate. Actually, I thought the Naval Observatory was *the* master clock (at least that's what they told us on their tour!). NBS or whatever it is now uses the USNO clock as the prime reference. However, I have no idea whether their dialup frob is reliable or not (evidentally not!). --bruce
efb@SUNED1.NSWSES.NAVY.MIL (Everett F Batey II) (01/04/91)
If there is a serious interest in getting to the bottom of the differences issue, why not call or email the horses mouth. usno is in the DC phone book and can probably be reached at somewhere near ( postmaster | root | system AT usno01.usno.navy.mil ). Incidentally when kicking around the right time vs the right frequency, you may note that NIST is it for frequency and USNO is it for time. Not to start an argument .. Congress said so .. not me. What ever factual, you learn, be sure and pass it on .. inquiring minds want to know .. /EV/ On Jan 2, 3:15, Marc de Groot wrote: >In article <69@rel.mi.org> bob@rel.mi.org (Bob Leffler) writes: > >Last time I looked it up, the National Bureau of Standards claimed that >time accuracy when TELEPHONING the WWV audio in Fort Collins, CO. was >"not better than 30 milliseconds". It sounds to me like 12 seconds is >not telephone network delay. > >Given a choice between WWV and the Naval Observatory, you should consider >WWV to be more accurate. > >It would be interesting to find out why there's such a discrepancy. }-- End of excerpt from Marc de Groot -- + efb@suned1.nswses.Navy.MIL efb@gcpacix.uucp efb@gcpacix.cotdazr.org + + efb@nosc.mil WA6CRE Gold Coast Sun Users Vta-SB-SLO DECUS gnu + + Opinions, MINE, NOT Uncle Sam_s | b-news postmaster xntp dns WAFFLE +
Craig_Everhart@TRANSARC.COM (01/05/91)
While I fear to comment on this sort of thing with real Wizards listening, I'd venture to say that the two sources account for the to-date accumulation of leap seconds differently. One source ignores them, the other includes them. Have I made a fool of myself now? Craig