How to secure fair timekeeping
– even with 0.1s precision
How much is 0.1s?
Why is exact timekeeping
difficult?
Required procedures and
equipment
Where can you seek
advice?
Henning Spjelkavik - IT Commission
how much is 0.1s?
Assume:
3 min/km in the finish sprint
=> 0.1s is 50 cm
If it’s an uphill finish lane, maybe
less than 30 cm
To avoid rounding problems, the
accuracy must be the double
Measure a difference of 15-25 cm
Henning Spjelkavik - IT Commission
why is fair 0.1s difficult?
Fairness within 25 cm at all levels
in the start procedure
throughout the competition
in the finish
Problems may give the wrong
medalists
Henning Spjelkavik - IT Commission
how to do timekeeping?
Write down the exact starting time
Write down the exact finish time
The result is the finish time
(minus) start time
Maximum error must be below
0.05s
One single, stable clock, with low
drift
Henning Spjelkavik - IT Commission
equipment
Start gate
Photo cell
Connected to printer and clock
Recorded order of start numbers
Procedures at start and finish
Video for photo finish
Video for documentation
Henning Spjelkavik - IT Commission
Start gate
setup
0.1s Timing
WOC Class
Start
Start pulse
Start pulse
Photo cell
Finish
Finish officials
Primary
system (A)
Secondary (B)
Order of the runners
Server
Operator
Henning Spjelkavik - IT Commission
Operator
wrong timing is a real possibility
Start clock (too fast)
Diff
Emil, starts 12:00:00.40
Finish clock
Actual
0:32:54.3
0:32:54.3
0:32:54,4
0:32:54,2
12:00:00.40
Emil, finish
12:32:54.84
0.10
12:32:54.74
Anders,
starts
13:08:00,48
0.22
13:08:00,26
Anders,
finish
13:40:55,05
0.33
13:40:54,72
Method: Two clocks. Time-of-day is transferred. Drift: 1s/5h
Henning Spjelkavik - IT Commission
Correct
other sports
Alpine skiing has detailed
requirements
Homologated timers
Hand timing is mandatory
0.01s – but race time is 1/10th
Athletics (Rule 165.25)
On the tracks (up to 10 000 m) – fully
electronic – 0.01s
Outside the tracks (marathon etc) 1s
Cross-country skiing (WC)
Transponders, photo cell
Henning Spjelkavik - IT Commission
where to get advice?
IT Commission
We plan to make a timing guide,
extending upon the WC
Guidelines 2004
Experienced organisers and other
Event Advisors
Timing services companies?
Your local cross-country skiing
club, running club etc
Henning Spjelkavik - IT Commission
quartz accuracy – bonus slide
Specifications of timing systems
PPM = Parts pr million, microseconds pr second
Examples
PPM
ms/s
drift/h
drift/day
drift/4h
30
0.00003
0.11
2.59
0.43
100
0.0001
0.36
8.64
1.44
RTR2, Sport ident
10
0.00001
0.04
0.86
0.14
CP520, +20
0.5
5E-07
0.00
0.04
0.01
CP520, -20 - +70
2.5
2.5E-06
0.01
0.22
0.04
Emit tag
10 PPM in winter, -30
Theoretically, two separate clocks may be used, if they are of proper
garanteed quality. The combined drift must be less than 0.05s, that is
0.02s/4h which is at least a 1 PPM crystal. Add possible temperature
differences, software error etc to the equation.
Henning Spjelkavik - IT Commission
conclusion
Secure 0.1s timing requires proper
equipment and procedures
Current recommendation:
automatic start (start gate)
automatic finish (photo cell)
a single source of time
correct pairing of runners and times
Correct results, in close and exciting
races!
Questions?
Henning Spjelkavik - IT Commission