Re: portable atomic clocks

From: Bjoern Gimle (b_gimle@algonet.se)
Date: Wed Jan 17 2001 - 11:13:27 PST

  • Next message: Alan Pickup: "Decay watch: 2001 Jan 17"

    > > You can try a free program called "Dimension 4", which you can download
    > > at http://www.thinkman.com/dimension4/index.html  No special hardware
    > > needed, just a dial up connection!
    >
    > I use Dimension 4; works very well at home & at work.
    >
    I  looked at its web site - it's the first of several I looked at that
    promises 0.1 second accuracy or better over the web. Others have stated that
    even with two-way communication, the www delay cannot be accurately
    measured, since it may be different for send/receive.
    
    I have a (cheap) radio clock receiving Frankfurt, Germany. It seems
    reliable, but it has always been off by 0.6 to 1.2 seconds from the new
    Swedish telephone speaking clock, which claims 0.01 (or 0.001) s accuracy.
    
    We used to have a public service on dial-up (direct modem-to-modem)
    connection, which DID measure round trip time, adjusted the PC clock to 1/18
    s , and kept a log of all adjustments made. It was converted to a private
    service at about $0.65 per call, and I don't know if it still operates.
    
    There is a program which does low-level (BIOS?) adjustments to keep the PC
    clock accurate for days after a synchronization, available at SeeSat or
    Clifford's or McCants' or ...   ( RighTime, AccuRite, KeepTime ...?)
    
    
    
    
    -- bjorn.gimle@tietotech.se (office)                         --
    -- b_gimle@algonet.se (home)  http://www.algonet.se/~b_gimle --
    -- COSPAR 5919, MALMA,    59.2576 N, 18.6172 E, 23 m         --
    -- COSPAR 5918, HAMMARBY, 59.2985 N, 18.1045 E, 44 m         --
    
    
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