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I found an old wind up watch that I had not used in years. I got it
serviced but it was running slow so I adjusted it. It went from running
150 seconds a day slow to running 21 seconds fast. Not too bad for the
first attempt, I thought.
Now that I know that the adjustment lever has the range, I will be
scientific. So I recorded the tick on my tablet (1 GHz CPU) and analysed
it. I also recorded a quartz watch as a reference. Damned if the wave
form was > 0.6% out. That is nearly 9 minutes out in a day. It looks
like I will have to revert to the old fashioned method of adjust, let it
run for a day and repeat until I get fed up.
Could do better if it tried. :-(
--
Regards
Stephen
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From: Warp
Subject: Re: 1 GHz CPU and it still cannot time things properly.
Date: 29 May 2012 12:33:27
Message: <4fc4fa56@news.povray.org>
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Stephen <mcavoys_at@aoldotcom> wrote:
> Now that I know that the adjustment lever has the range, I will be
> scientific. So I recorded the tick on my tablet (1 GHz CPU) and analysed
> it. I also recorded a quartz watch as a reference. Damned if the wave
> form was > 0.6% out. That is nearly 9 minutes out in a day.
It actually doesn't surprise me that CPU clocks aren't adjusted to
extreme accuracy because they don't need to. It's not like they have to
precisely sync with anything. This especially so because most modern CPUs
support throttling. (In fact, an error 0.6% sounds pretty small to me.)
--
- Warp
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From: Orchid Win7 v1
Subject: Re: 1 GHz CPU and it still cannot time things properly.
Date: 29 May 2012 12:38:36
Message: <4fc4fb8c$1@news.povray.org>
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On 29/05/2012 05:19 PM, Stephen wrote:
> It looks
> like I will have to revert to the old fashioned method of adjust, let it
> run for a day and repeat until I get fed up.
> Could do better if it tried. :-(
You could try using the atomic emission spectrum of caesium-133 to
adjust the frequency of the quartz oscillator...
For reference, the frequency of photon generated by the transition
between the two hyper-fine ground states of a caesium-133 atom is
*defined as* 9,192,631,770 Hz. As in, that's the current SI definition
of what one second *is*.
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From: Stephen
Subject: Re: 1 GHz CPU and it still cannot time things properly.
Date: 29 May 2012 15:12:05
Message: <4fc51f85$1@news.povray.org>
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On 29/05/2012 5:33 PM, Warp wrote:
> It actually doesn't surprise me that CPU clocks aren't adjusted to
> extreme accuracy because they don't need to. It's not like they have to
> precisely sync with anything. This especially so because most modern CPUs
> support throttling. (In fact, an error 0.6% sounds pretty small to me.)
last night before going to sleep and in the morning I went full steam
ahead, at it. Maybe I just miss working for a living.
others you measured parts per million. When you expect to get a watch
running to +/- 2 seconds a day it is galling to have to do it by iteration.
--
Regards
Stephen
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From: Stephen
Subject: Re: 1 GHz CPU and it still cannot time things properly.
Date: 29 May 2012 15:16:02
Message: <4fc52072$1@news.povray.org>
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On 29/05/2012 5:38 PM, Orchid Win7 v1 wrote:
>
> You could try using the atomic emission spectrum of caesium-133 to
> adjust the frequency of the quartz oscillator...
>
Sh*te! I forgot. I have one of those in the back shed, as well.
> For reference, the frequency of photon generated by the transition
> between the two hyper-fine ground states of a caesium-133 atom is
> *defined as* 9,192,631,770 Hz. As in, that's the current SI definition
> of what one second *is*.
*/- a minute a month will do me. Actually twice a day will do if I
forget to wind it up. :-P
--
Regards
Stephen
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From: Orchid Win7 v1
Subject: Re: 1 GHz CPU and it still cannot time things properly.
Date: 29 May 2012 16:03:54
Message: <4fc52baa$1@news.povray.org>
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>> You could try using the atomic emission spectrum of caesium-133 to
>> adjust the frequency of the quartz oscillator...
>
> Sh*te! I forgot. I have one of those in the back shed, as well.
0wned.
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From: Stephen
Subject: Re: 1 GHz CPU and it still cannot time things properly.
Date: 29 May 2012 16:27:41
Message: <4fc5313d@news.povray.org>
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On 29/05/2012 9:03 PM, Orchid Win7 v1 wrote:
>>> You could try using the atomic emission spectrum of caesium-133 to
>>> adjust the frequency of the quartz oscillator...
>>
>> Sh*te! I forgot. I have one of those in the back shed, as well.
>
> 0wned.
And never called me mother!
--
Regards
Stephen
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From: scott
Subject: Re: 1 GHz CPU and it still cannot time things properly.
Date: 30 May 2012 03:57:16
Message: <4fc5d2dc$1@news.povray.org>
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> Now that I know that the adjustment lever has the range, I will be
> scientific. So I recorded the tick on my tablet (1 GHz CPU) and analysed
> it. I also recorded a quartz watch as a reference. Damned if the wave
> form was > 0.6% out.
There is no reason for a tablet (or any PC/phone) to have a clock
generator with super accuracy, it's simply wasted expense when an
accuracy of <1% will do for the majority of tasks. That's why
professional sound cards have an option to use the clock from an
incoming signal (rather than the internal one) to keep everything in sync.
Try playing the same song (or your tick recording) on several different
devices at the same time, you'll find they likely drift apart noticeably
after only a minute or two.
You could try recording the speaking clock as a reference, that is
probably more accurate than your tablet.
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From: Orchid Win7 v1
Subject: Re: 1 GHz CPU and it still cannot time things properly.
Date: 30 May 2012 05:17:34
Message: <4fc5e5ae$1@news.povray.org>
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On 30/05/2012 08:57 AM, scott wrote:
> Try playing the same song (or your tick recording) on several different
> devices at the same time, you'll find they likely drift apart noticeably
> after only a minute or two.
And here I was thinking that even cheap quartz oscillators are quite
accurate...
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From: scott
Subject: Re: 1 GHz CPU and it still cannot time things properly.
Date: 30 May 2012 07:01:59
Message: <4fc5fe27$1@news.povray.org>
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>> Try playing the same song (or your tick recording) on several different
>> devices at the same time, you'll find they likely drift apart noticeably
>> after only a minute or two.
>
> And here I was thinking that even cheap quartz oscillators are quite
> accurate...
Even cheap quartz oscillators are too expensive to just throw at a
device like a tablet. The audio clock is likely derived from elsewhere
with whatever divide-down ratio was cheapest to implement (the frequency
will likely not even be designed to be spot on 44100 if the numbers
don't work out nicely).
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