How difficult would it be to make two electronic containing boxes that could be placed a few meters away from each other to make goal posts for a football(soccer) game?
There would have to be some sort of radio chip in/on the ball and when the ball passed between the two boxes there would be some sort of noise(maybe crown cheering).

IFAB is exploring options. Most of them employ a chip in the ball. The criteria for such a system are strict:

Any proposed system seeking IFAB approval must meet the following four principles:
-The technology should apply only to goal-line technology
-The system must be 100% accurate
-The indication of whether or not the ball has crossed the line must be instantaneous between the system and the referee
-The signal is communicated only to the match officials.

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I was thinking more about football in the park really but it seems, from what you say, that it is practical.

Doesn't this already exist in the form of those little tabs stores place inside books and DVD/CD boxes that set off the alarm when you try to steal them or the cashier does not de-whatever that pad does's them?

It might take more sensors or more power, but the strip itself is very small and could probably fin inside the ball or under each "panel" on the outside.

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It's not so much the technology as the preciseness of the sport... "the whole of the ball entirely crosses the line...". WalMart isn't concerned with you getting all of the CD out the door before they pounce.

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Never attribute to malice what can be adequately explained by ignorance or stupidity.
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Ahh, I thought it was like American football where the ball only has to break the plane of the goal line.

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Easy, just do two sensors on each post, ball-width apart (foremost sensor at back edge of goal line, the second one ball-width behind goal line). Then they only have to trip in sucessive order. Have one "bar" per panel in the ball, then rotation wouldn't matter.

Edit: upon contemplation, the first sensor would be redundant. Just put one set of sensors ball-width behind line

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When I saw the title of this thread, I thought it was about people in the conspiracy theories forum continuously jumping goal posts during the debate.

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Can't they use an otical system such as the ones used for garage doors, or Jean Michel Jarre's "laser harp?"?

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THe problem is, the sensor field isn't planar - it's more torroidal. In store sensors, this is a good thing. On a football field - it would be darn near impossible to do.

Still.. if you were to use 3 or more sensors (say, two on the goal posts and two some significant distance behind, then make use of algorythms similar to those used by cell phone companies to locate you (without GPS)...I'd think a fair degree of accuracy could be attained..

Or.. simply introduce a layer of radar-reflective mylar to the ball (inside, of course). Set up.. no fewer than 4 (very low power) radar guns (at least enough so that at least three cover any point in the goal mouth). Then simple trigonometry would give you accurate ball placement.

The system used by TV to show balls/strikes in baseball wouldn't work - I believe that's based on the apparent size of the ball - which, of course, must be 100% visible at the time of the measurement.

There are other requirements, not on the list - the system has to be rugged - bodies and balls can do a lot of damage to sensitive electronics. Not to mention the weather.
Furthermore, whatever system we come up with, can't interfere with play.

Having gone through all that - I here state that I'm against any such system - just as I'm against it in baseball. The umpire/referee is a part of the game - and so are any errors he makes. The device might make a good training aid, but don't use it in a real game

IN a pickup game - it would be easy to do, if you don' t mind a LITTLE inaccuracy. Get two 8-foot poles. Mount a BUNCH of those garage door sensors - as tightly together as you can - from top to bottom. A simple circuit will tell you if the plane is broken. You would still have to determine if it was ball or body that broke the plane, but there'd be little doubt that SOMETHING crossed the line.

Football isn't, and shouldn't be, an exact science. Complaining about what seems like gross injustice is part of the fun of being a supporter!

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I tend to agree. Referee judgement is part of the game. I'd rather live with some human error than have everything automated.

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With imaging technology where it's at today, what's wrong with using a few well placed cameras. Heck, they could even put a couple in the ball itself.

Personally, I would like to remove human error in officiating from all games. During some MLB games they give the shot from above the plate and it is appalling how inconsistent the umpires can be. It is not unusual to see a ball 5 or 6" off the plate get called a strike. That's just too much error for how hard modern pitching is to hit even when the calls are good.

I played a few softball tournaments where a mat was used (instead of the umpires judgement). So much better, no doubt and no arguing. If it hit the mat, it was a strike, if not, a ball. True, a very crude example; but I think a valid one.

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During some MLB games they give the shot from above the plate and it is appalling how inconsistent the umpires can be. It is not unusual to see a ball 5 or 6" off the plate get called a strike. That's just too much error for how hard modern pitching is to hit even when the calls are good.

Whiner
The first Indains game this season, against the Chi-Sox, was a great example of this. His calls were wildly inconsistant. But they were wildly inconsistant for both teams. Not like it gave one an advantage and not the other. It's part of the game. They probably tested him for narcotics afterwards, and the Indians won the away game so he probably needed some protection leaving the stadium. But that's baseball.

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