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'Real time' Wireless communication (Fencing scoring)

Hi All,

I started taking fencing lessen a few months ago.I also learned also about the 'wired' kind of scoring system they use in fencing:

A switch is mounted on the wapons tip and is wired through the uniform to a cable that unrolls from the wall. Lights indicate wich switch is pressed first.

My first reaction was offcoarse: why don't we do this wireless ? Ofter some searches a learned that such systems exist, but that they are not very reliable and are very expensive.

My intuition still says that this kind of system shouldn't be to difficult to engineer these days.

I understand that Frequency-Hopping and Spread spectrum tranceiver are not the best choice.

Requirements for a tranceiver would be:

-Known latency

-As fast as possible

-Multi-channel

Any other opinions on this topic ? Is there something i realy overlooked ?

Thanks for any insights.

Stijn.

Reply to
Jon S.
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What about reliability ? Impact resistance.

More importantly weight. Cost . Not every country that fences could afford such a system even if you got the price for the equipment down the system would have to be certified before it could be used.

Also K.I.S.S. and if the sport is happy with the present system why change it.

Security, have to guarentee that the system isn't hackable.

Alex Gibson

Reply to
Alex Gibson

Pun intended?

Reply to
Rick Merrill

I am not sure I understand the wired system. The OP said it uses a "switch" in the tip. I had the impression that the tip was one end of the switch and a vest worn by the opponent was the other end. When tip touched the vest, the circuit was completed. Is this not right? Is there a switch in the tip which does not care what it touches?

I believe I could develop a wireless system that would meet all the reqirements you have stated. I have seen systems for detecting touch by using conducted low end RF (>100 kHz). Very little energy is needed and the frequency can be tuned so that you and your opponent are distinguishable. The problem of "simultaneous" hits can be resolved by shutting down your touch oscillator when a touch is detected. Then your opponent can not detect a touch until you remove your tip. A circuit should be able to resolve to much better than 40 ms. A very simple wireless interface (or as complex as security needs) can be used to indicate a touch to the scoring equipment.

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Reply to
rickman

... snip ...

I believe you must be right about the tip being a contact. IIRC a 'hit' is only valid on certain areas, and that can be controlled by the conductivity of clothing areas. All this is very simply controlled by wires and current flow. Once you eliminate the wires the complications are going to abound. KISS.

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Reply to
CBFalconer

It depends which weapon you are using. For a foil you do have a conductive vest but if you use an epee then the tip *is* a switch. The three wires allow you to distinguish (1) a hit, (2) a coquile** hit and (3) a floor hit (if you have a mat). ** - guard.

Andrew

Reply to
Andrew Jackson

I agree entirely! I think that one can have great sympathy with a fish after going fencing (but then the fishing reel isn't likely to explode into the fish). Sorry to hear that you did get caught.

Andrew

Reply to
Andrew Jackson

Thanks to all for the constructive reply's.

I already had the impression that designing a reliable, three weapon device that can be certified for competition will be a hard job (altough not imposible)

Im my club, all adult amateur fencers practice epee.I don't know if this is true in general. (for the non-fencers: epee is considered as being closest to the original duel, you can be touched everywhere on the body, and the one who touches first is scoring)

I still like the idea of designing a non-commercial but reliable one weapon(epee) system for recreational use. I don't know how important 'tip to floor' and 'tip to tip' contact is.I haven't seen a conductive floor in amateur fencing. If not, it leaves us with only one switch (normaly open) on each side.This shouldn't be to dificult to make wireless, even considered ms timing constraints.

Does such a 'stripped down' still make sense for an amateur fencer ? And if so, any suggestion for technology to use ?

I started looking into simple 'car-key' tranceivers. At work i design products that use wireless technology (Aerocomm, Maxstream...) for serial communication. Altough very reliable, i think these devices aren't the way to go with 'ms' timing constraints.

Stijn

Reply to
Jon S.

Have you seen the "spike" wireless technology (targeted for wireless game controllers)?

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Reply to
RM

Thanks for the link. They list a 5.5 ms latency in their datasheets...

Stephen, any idea what kind of latency we should be looking for ? How 'fast' is epee fencing ?

Stijn

Reply to
Jon S.

There are two timing issue in the rules. One is minimum touch time, and the other is discrimination between "simultaneous" hits which are more common than one would think. I don't have a copy of the current rule book and I'm off on a trip tomorrow until the weekend.

You really do need a copy of the FIE rules and someone at your club will have them. See also

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According to my club chairman, Espada will be installing two electric pistes this year. It seems that lighter portable pistes are becoming available.

Stephen

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Reply to
Stephen Pelc

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