Question about the ski events - Canadian TV, Computing and Home Theatre Forums

Bayguy · 2010-02-20, 04:47 PM

Hi this isnt about a specific sking event so I didn't put it under one of those threads, hope thats okay.

We're just watching the x-country skiing which is very pretty. Did you see the snowmen on the biathalon course the other day?

Havent seen any yet today. Anyway, how do they get such acurate times for the skiiers? I thought maybe they have those little tags on their boots like runners use, but when theres a photo finish its who's ski crosses the finish line first not their foot. But the tag can't be on the ski because like in a little while these guys are going to change to different skis. They are showing 1/10ths of a second timings so tehre must be some kind of sensors on the track and on the skiers but I can't figure out how they do it.

Also on ski jumping, how do they know where the ski touched the ground? I dont think they have sensers under all the snow.

'Cuz they cant measure how far somebody went until they hit the ground.

Hope these aren't dumb questoins but we can't figure it out.

Thanks!

Mach2billy · 2010-02-20, 06:04 PM

Hi Bayguy

Cross-country skiing uses 2 timing systems, one main, one backup, and both are set to time to 1/1000 of a second. The start gate has a switch on it to start the timer when the gate is opened, and the finish has photo cells that sense when the skiers cross the line and break the beam of light. Here is a link to the FIS rules, if you're interested: FIS XC rules.pdf

According to the FIS rules for ski jumping, they use both manual and 'technical distance measuring systems:

The Measuring of the Jumping Distance by the Distance Measurers
The distance measurers stand on one side of the landing slope and follow the jumper's trajectory with their eyes up to the landing point. The measurer in whose measuring area the viewed jump landed shall mark the jumping distance to an accuracy of 0.5 m. The mark to be awarded is indicated by the placement of the measurer's hand on the distance markings. Half meters are indicated by an additional raising of the free arm. The distance markings shall be placed on both sides of the landing slope to prevent parallax mistakes by the markers.

Technical measuring devices that measure distances to an accuracy of 0.5 meter and tabulate the distance are permitted for the recording of the jumping distance and the calculation of distance points.

Distances must also be practically measured by distance measurers as a back-up and in case of mechanical failure of the technical measuring device.

Bayguy · 2010-02-20, 07:27 PM

Hi billy tnx for the info. So the ski jumping is done by people watching? I still dont understand how they know when the skiis have touched the ground. Maybe there are people laying on their stomachs next to the snow that I havent seen. And I don't really understand how the photo equipment on the x-c can tell whose crossing the line when its still early in the race and lots of people are going across the line at once. So they don't use anything on their boots?

LeavingSC · 2010-02-22, 11:09 AM

Pretty sure the cross-country skiers have tags on their boots or ankles. At the finish line there is a trench which I presume is a sensor mat to detect the tags. But I think these are used for rough timing purposes (and for TV display) and the light sensors and photo finishes are used for more accuracy if the times are close to each other within a certain tolerance.

AFF · 2010-02-22, 11:30 PM

So if thats the case does it register when they leave the starting gate? Some guys are 40ft from the start line in those mass starts. If they are back that far from the start line 5 seconds could pass before they get to it.

2010-02-20, 04:47 PM	#1
Bayguy Join Date: Oct 2009 Location: Baja BC Posts: 489	Question about the ski events Hi this isnt about a specific sking event so I didn't put it under one of those threads, hope thats okay. We're just watching the x-country skiing which is very pretty. Did you see the snowmen on the biathalon course the other day? Havent seen any yet today. Anyway, how do they get such acurate times for the skiiers? I thought maybe they have those little tags on their boots like runners use, but when theres a photo finish its who's ski crosses the finish line first not their foot. But the tag can't be on the ski because like in a little while these guys are going to change to different skis. They are showing 1/10ths of a second timings so tehre must be some kind of sensors on the track and on the skiers but I can't figure out how they do it. Also on ski jumping, how do they know where the ski touched the ground? I dont think they have sensers under all the snow. 'Cuz they cant measure how far somebody went until they hit the ground. Hope these aren't dumb questoins but we can't figure it out. Thanks!

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

2010-02-20, 06:04 PM	#2
Mach2billy Join Date: May 2005 Location: Toronto, Rogers SA3250HD, Sony MFMHT75W Posts: 173	Hi Bayguy Cross-country skiing uses 2 timing systems, one main, one backup, and both are set to time to 1/1000 of a second. The start gate has a switch on it to start the timer when the gate is opened, and the finish has photo cells that sense when the skiers cross the line and break the beam of light. Here is a link to the FIS rules, if you're interested: FIS XC rules.pdf According to the FIS rules for ski jumping, they use both manual and 'technical distance measuring systems: The Measuring of the Jumping Distance by the Distance Measurers The distance measurers stand on one side of the landing slope and follow the jumper's trajectory with their eyes up to the landing point. The measurer in whose measuring area the viewed jump landed shall mark the jumping distance to an accuracy of 0.5 m. The mark to be awarded is indicated by the placement of the measurer's hand on the distance markings. Half meters are indicated by an additional raising of the free arm. The distance markings shall be placed on both sides of the landing slope to prevent parallax mistakes by the markers. Technical measuring devices that measure distances to an accuracy of 0.5 meter and tabulate the distance are permitted for the recording of the jumping distance and the calculation of distance points. Distances must also be practically measured by distance measurers as a back-up and in case of mechanical failure of the technical measuring device.

2010-02-20, 07:27 PM	#3
Bayguy Join Date: Oct 2009 Location: Baja BC Posts: 489	Hi billy tnx for the info. So the ski jumping is done by people watching? I still dont understand how they know when the skiis have touched the ground. Maybe there are people laying on their stomachs next to the snow that I havent seen. And I don't really understand how the photo equipment on the x-c can tell whose crossing the line when its still early in the race and lots of people are going across the line at once. So they don't use anything on their boots?

2010-02-22, 11:09 AM	#4
LeavingSC Join Date: Oct 2004 Location: Elmira, Ontario Posts: 98	Pretty sure the cross-country skiers have tags on their boots or ankles. At the finish line there is a trench which I presume is a sensor mat to detect the tags. But I think these are used for rough timing purposes (and for TV display) and the light sensors and photo finishes are used for more accuracy if the times are close to each other within a certain tolerance.

2010-02-22, 11:30 PM	#5
AFF Join Date: Apr 2007 Posts: 676	So if thats the case does it register when they leave the starting gate? Some guys are 40ft from the start line in those mass starts. If they are back that far from the start line 5 seconds could pass before they get to it.