'Real time' Wireless communication (Fencing scoring)

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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.

Re: 'Real time' Wireless communication (Fencing scoring)

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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



Re: 'Real time' Wireless communication (Fencing scoring)
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Pun intended?


Re: 'Real time' Wireless communication (Fencing scoring)
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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.  

--

Rick "rickman" Collins

snipped-for-privacy@XYarius.com
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Re: 'Real time' Wireless communication (Fencing scoring)
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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.

--
Chuck F ( snipped-for-privacy@yahoo.com) ( snipped-for-privacy@worldnet.att.net)
   Available for consulting/temporary embedded and systems.
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Re: 'Real time' Wireless communication (Fencing scoring)
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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



Re: 'Real time' Wireless communication (Fencing scoring)
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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




Re: 'Real time' Wireless communication (Fencing scoring)
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

Re: 'Real time' Wireless communication (Fencing scoring)
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Have you seen the "spike" wireless technology (targeted for wireless game
controllers)?
http://www.elevenengineering.com/products/SPIKE.asp



Re: 'Real time' Wireless communication (Fencing scoring)
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

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Re: 'Real time' Wireless communication (Fencing scoring)
On 24 May 2004 03:11:20 -0700, snipped-for-privacy@hotmail.com (Jon S.)

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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
  www.fie.ch
  www.britishfencing.com

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

Stephen
--
Stephen Pelc, snipped-for-privacy@INVALID.mpeltd.demon.co.uk
MicroProcessor Engineering Ltd - More Real, Less Time
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