[time-nuts] Visual clock comparison

d0ct0r time at patoka.org
Sun Apr 19 13:27:31 EDT 2015

Thank you all for interesting information to read !
After few experiments I made a conclusion it is very subjective measure. 
Its like how are you "feeling" it. Say if I "feel" that my clock is 
"good" - I see that my clock is almost in sync. with "master clock". The 
other day if I "feel" that my clock is far from perfect, I see the big 
gap. ;-))))

The best approach, I think, is using camera and slow motion. Then you 
could "rewind it" and see how it is.

Here is the link to the YOUTUBE: https://youtu.be/GScyoA8gCzY



On , Tom Van Baak wrote:
> That would make a fun time experiment. One that you should do and
> report back to us.
> I see two experiments: one using LED flashes and one using speaker 
> ticks.
> In each case output a main and a delayed pulse. Try it yourself, and
> with a number of friends.
> The goal is to find at what level people can discern the difference
> between, or the order of, two events.
>> From the data you can determine both a human average and an average 
>> human response.
> Use identical LEDs, and identical speakers.
> Also, use a common timing source. Do not compare CHU with NTP with PC
> monitor with PC speakers; all that does is introduce layers of unknown
> offsets into your experiment. This is would be an easy Arduino /
> Raspberry-Pi sort of project.
> For higher precision, see pd26.asm and pd27.asm (
> http://leapsecond.com/pic/src/ ) as an example of precise pulse
> stepping.
> If this turns out to give reliable data, you can then try different
> color LEDs and different frequency speaker ticks to see what effect
> that might have on resolution. Also try different pulse durations to
> see if human leading edge detection is affected by pulse width.
> For those of you with a Stanford Research DG535 and two spare LEDs,
> give it a try right now.
> http://www.thinksrs.com/products/DG535.htm
> /tvb
> ----- Original Message -----
> From: "d0ct0r" <time at patoka.org>
> To: "Discussion of precise time and frequency measurement" 
> <time-nuts at febo.com>
> Sent: Friday, April 17, 2015 11:16 AM
> Subject: [time-nuts] Visual clock comparison
>> Hello, Netizens !
>> I am wandering what is the average human ability to visually compare 
>> two
>> clocks ? Let say I have XClock application running on one machine
>> (stratum 1 NTP) and I have my project clock close by. And I would like
>> to match the reading. If I'll see the difference, which range it will 
>> be
>> ? 100ms or so ?
>> I also tried to use my ears (CHU radio signals and clock display, NRC
>> phone line). However NRC "Talking Clock" could be routed via Satelite
>> which will compromise the "reading" a little bit. Thanks !
>> --
>> WBW,
>> V.P.
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