Welcome to the NavList Message Boards.

NavList:

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

Compose Your Message

Message:αβγ
Message:abc
Add Images & Files
    or...
       
    Reply
    Re: Setting seconds on a digital display
    From: Frank Reed
    Date: 2016 Aug 24, 09:30 -0700

    Greg Rudzinski, you wrote:
    "When setting a Casio digital wrist watch I hack it to the exact tick by short wave"

    This is what I was always taught, and I think most people do it this way. We even take a certain pride in hitting the button "right on the beep". Whether it's "right" or not depends on what we want the watch to read. Should it display the current time, to the nearest second, or should it display the last second that "ticked over". In the former case, the error in reading the time is -0.5 to +0.5 seconds with a mean error of 0.0 seconds. In the latter case, the error in reading is -1.0 to 0.0 seconds with a mean error of -0.5 seconds. It seems to me that when we do this by short wave or some other time source trustworthy to a tenth of a second, we should make an effort to start or set the watch about half a second before the tick. Then the mean error in the displayed time is zero.

    Note that there are plenty of other errors to worry about when we get down to a single second. There's the reaction time error, which you alluded to. There's also the DUT correction --that fraction of a second that separates UTC (atomic time) from UT1 (earth rotation time). But none of those matter either if the watch is off by an average of 0.5 seconds...

    Frank Reed

       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Join NavList

    Name:
    (please, no nicknames or handles)
    Email:
    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:

    Email Settings

    Posting Code:

    Custom Index

    Subject:
    Author:
    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