Accuracy of Stopwatch

Post a reply


This question is a means of preventing automated form submissions by spambots.
Smilies
:D :) ;) :( :o :shock: :? 8-) :lol: :x :P :oops: :cry: :evil: :twisted: :roll: :!: :?: :idea: :arrow: :| :mrgreen: :geek: :ugeek:
BBCode is ON
[img] is ON
[flash] is ON
[url] is ON
Smilies are ON
Topic review
   

If you wish to attach one or more files enter the details below.

Expand view Topic review: Accuracy of Stopwatch

Re: Accuracy of Stopwatch

Post by Stopwatch » Sat May 21, 2011 9:58 am

JanHgm wrote:Same for most Windows clocks but also that different Windows clocks on one system all produced different results.

There are a few PC's clock hardware. Do they distinguish them or just test "a software as is"?

Re: Accuracy of Stopwatch

Post by JanHgm » Fri May 20, 2011 12:50 pm

Last week I visited the Dutch National Measurement Institute of Time. These guys produce the NTP for the Nordic region.
My camera equipment was measured in their lab. My software required certification and now I can prove that I achieved a nearly e-8 correctness over 24 hour with camera/pc timing.

What I learned at the lab was that regular stopwatches are all inaccurate. Same for most Windows clocks but also that different Windows clocks on one system all produced different results.

Conclusion, timing is complicated business

Janhgm

Re: Accuracy of Stopwatch

Post by Stopwatch » Sat May 22, 2010 10:38 am

KSoko wrote:
Stopwatch wrote:What hardware and OS? Did you tried this build viewtopic.php?f=3&t=932#p1181

We tested few laptops (hp, toshiba, dell), mostly with XP and VISTA.
We didn't know nothing about HPET at this time, so we used the regular version of the software. I'm not sure if the notebooks are equipped with HPET-chips.

HPET is available over 5 years but only Vista and later takes advantage of it. Could you retest the build above on the same notebooks?

KSoko wrote:
Stopwatch wrote:
KSoko wrote:just that on the second notebook
occasionally crashes if there is a parallel running macro in excel

Are you using Excel integration?

Jep, but that with the 15sek. jump was without running macros.

Is there regularity of these crashes?

Re: Accuracy of Stopwatch

Post by KSoko » Fri May 21, 2010 8:03 am

Stopwatch wrote:
KSoko wrote:drift over 9sec. for 2 hours (between the notebooks)
one "jump" from 15sek.

What hardware and OS? Did you tried this build viewtopic.php?f=3&t=932#p1181

We tested few laptops (hp, toshiba, dell), mostly with XP and VISTA.
We didn't know nothing about HPET at this time, so we used the regular version of the software. I'm not sure if the notebooks are equipped with HPET-chips.

Stopwatch wrote:
KSoko wrote:just that on the second notebook
occasionally crashes if there is a parallel running macro in excel

Are you using Excel integration?

Jep, but that with the 15sek. jump was without running macros.

Re: Accuracy of Stopwatch

Post by Stopwatch » Thu May 20, 2010 1:07 pm

KSoko wrote:drift over 9sec. for 2 hours (between the notebooks)
one "jump" from 15sek.

What hardware and OS? Did you tried this build viewtopic.php?f=3&t=932#p1181

KSoko wrote:just that on the second notebook
occasionally crashes if there is a parallel running macro in excel

Are you using Excel integration?

Re: Accuracy of Stopwatch

Post by KSoko » Wed May 19, 2010 8:36 am

hi there
nice soft, but unfortunately not stable and accurate enough to use it in open events.

Our experience with use on a MTB-DH event -> running Xnote on 2 notebooks (start/final) ->
drift over 9sec. for 2 hours (between the notebooks)
one "jump" from 15sek. just that on the second notebook
occasionally crashes if there is a parallel running macro in excel

Re: Accuracy of Stopwatch

Post by JanHgm » Wed May 12, 2010 6:01 pm

Interesting discussion.

And if you are using a Finishlynx I expect that this is a line scan camera just as they are using in athletics.
You might be interested in the last development I made for athletics events using xNote a 30 fps IP camera and screen recording with Camstudio.

For this events I asked national committee how they verify that recording is accurate. Did not get an answer from the national organization but one of the time system vendors told me that the committees do not know how to verify measurement accuracy. They just believe what vendors tells them he said.

Some comments about your accuracy. With a race the start is give with a gun shot. Each 34 cm that the start sensor is away is a delay of 0,001 second.
Mostly athletics are some meters away so delay for them is more than 0,01 second.

So if you start a discussion about measurement and accuracy you have to take many other conditions in account as well.

Jan

Re: Accuracy of Stopwatch

Post by mikewest » Fri May 07, 2010 4:31 pm

So, this might be the only software project that I have ever seen where the feedback is incorporated so quickly. Wow.

I've got a road race Saturday (no timing, just a finishlynx camera for the pack of 40 riders going by in 4 seconds at the finish). I'll try the build on my

ancient computer (Asus P2F-B motherboard)
old laptop (Toshiba m200)
current desktop (some sort of Intel motherboard)

along with a couple of stopwatches that I have lying around.

I suppose I could also time against an atomic clock (my gps) and see what kind of drift i get, although the gps only has seconds resolution. But it should be VERY consistent

thanks,
mark

Re: Accuracy of Stopwatch

Post by Stopwatch » Mon May 03, 2010 5:48 pm

This build uses QueryPerformanceCounter which might utilize HPET (... may make use of RDTSC, but might instead make use of a timing devices on the motherboard or some other system services that provide high-quality high-resolution timing information).

Try out how it behaves.

xnsw.zip
Use of HPET
(166.04 KiB) Downloaded 2370 times

Re: Accuracy of Stopwatch

Post by mikewest » Sat May 01, 2010 1:05 am

I have done two simple tests with 3 clocks, ancient PC, old PC, and my handheld Robic stopwatch. I would suspect that the Robic stopwatch is the best because it is dedicated to being a stop watch while the PCs are just computer clocks. I don't know though.

I thought about it for a while. What we do for Bicycle Time Trials is that we set all stopwatches and the start clock (one of these: http://www.electronumerics.com/raceclock_lm.htm) about 1/2 hour before the first rider is off to the same time. Then the judges go to the finish line (typically 1/4 to 1/2 mile away) and record the finish times of the riders who go about a total of 10-15 miles based on their stopwatch. So, if the start clock is bang on, but the computer clock that we use to find the finish time is "slow" or looses time, then the last rider gets a small "bonus". (I think I got the signs all right. :) )

But I have no idea which clocks are accurate and which ones are off by a bit. At this point, I think it really isn't important..... Until we have a National Event. ;)

Thanks,
Mike

Top

cron