Welcome to the NavList Message Boards.


A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Add Images & Files
    Re: NIST website time accuracy
    From: John Huth
    Date: 2010 Jul 25, 07:59 -0400
    I believe they "ping" the internet connection to establish the round-trip time.   That is to say, if you send a signal to the host and it gets echoed back to you, you divide by 2 to get the one way trip time and then you factor that into the NIST time as a small correction.   Of course, the implication is that the time delay is always the same.

    I tried to check the drift in my wrist-watch using NIST time.   Of course the watch itself has a temperature issue, but I always wear it, and don't put it in freezers, so I'm assuming it's pretty good.   NIST did a good job tracking the drift, and I didn't see a lot of variation from one location to another.    I also checked it against radio broadcast time, which I assume doesn't suffer the delay issue and it works out reasonably well.

    On Sat, Jul 24, 2010 at 9:19 PM, John Karl <jhkarl@att.net> wrote:

    The U.S. National Institute of Standards & Technology (NIST) quotes a 0.2 second accuracy for their animated clock on their website http://nist.time.gov/timezone.cgi?Central/d/-6/java.

    Given the vagaries of internet transmission times, can anyone tell me how they do this??

    NavList message boards and member settings: www.fer3.com/NavList
    Members may optionally receive posts by email.
    To cancel email delivery, send a message to NoMail[at]fer3.com

    Browse Files

    Drop Files


    What is NavList?

    Join NavList

    (please, no nicknames or handles)
    Do you want to receive all group messages by email?
    Yes No

    You can also join by posting. Your first on-topic post automatically makes you a member.

    Posting Code

    Enter the email address associated with your NavList messages. Your posting code will be emailed to you immediately.

    Email Settings

    Posting Code:

    Custom Index

    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site