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.
'Real time' Wireless communication (Fencing scoring)
Started by ●May 14, 2004
Reply by ●May 16, 20042004-05-16
"Jon S." <jonsquire2000@hotmail.com> wrote in message news:f0ae8fc3.0405141103.5700a702@posting.google.com...> 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.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 by ●May 16, 20042004-05-16
Reply by ●May 16, 20042004-05-16
On 14 May 2004 12:03:41 -0700, jonsquire2000@hotmail.com (Jon S.) wrote:>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.At senior and international level these systems also have to be shown to be secure, and to work on multiple parallel pistes in the same room. Other problems you have to contend with are things like tip to tip contact, and tip to piste contact. Note also that in epee scoring you also have to cope with the simultaneous hit discrimination, which is of the order of 40ms as far as I remember, but I don't have the current rule book. Try doing a wired system first, and then you'll begin to see the problems. I built an all CMOS scoring box many years ago, and contact wetting was a real problem that the then current relay systems just did not suffer from. Although wiring and spools are currently heavy and unreliable, they have the advantage that the cost is usually born by the clubs, rather than by individual fencers, and small radio units will inevitably "walk". Don't let me put you off, but the *system* problems are non trivial. We'll all cheer when you find a repeatable solution at a reasonable price. Stephen P.S. Hampshire (UK) Foil Champion 1974/75 -- Stephen Pelc, stephenXXX@INVALID.mpeltd.demon.co.uk MicroProcessor Engineering Ltd - More Real, Less Time 133 Hill Lane, Southampton SO15 5AF, England tel: +44 (0)23 8063 1441, fax: +44 (0)23 8033 9691 web: http://www.mpeltd.demon.co.uk - free VFX Forth downloads
Reply by ●May 18, 20042004-05-18
Stephen Pelc wrote:> > On 14 May 2004 12:03:41 -0700, jonsquire2000@hotmail.com (Jon S.) > wrote: > > >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. > At senior and international level these systems also have to be > shown to be secure, and to work on multiple parallel pistes in the > same room. > > Other problems you have to contend with are things like tip to > tip contact, and tip to piste contact. Note also that in epee > scoring you also have to cope with the simultaneous hit > discrimination, which is of the order of 40ms as far as I > remember, but I don't have the current rule book. > > Try doing a wired system first, and then you'll begin to see > the problems. I built an all CMOS scoring box many years ago, > and contact wetting was a real problem that the then current > relay systems just did not suffer from. > > Although wiring and spools are currently heavy and unreliable, > they have the advantage that the cost is usually born by the clubs, > rather than by individual fencers, and small radio units will > inevitably "walk". > > Don't let me put you off, but the *system* problems are non > trivial. We'll all cheer when you find a repeatable solution > at a reasonable price.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 rick.collins@XYarius.com Ignore the reply address. To email me use the above address with the XY removed. Arius - A Signal Processing Solutions Company Specializing in DSP and FPGA design URL http://www.arius.com 4 King Ave 301-682-7772 Voice Frederick, MD 21701-3110 301-682-7666 FAX
Reply by ●May 18, 20042004-05-18
rickman wrote:>... snip ...> > 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 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 (cbfalconer@yahoo.com) (cbfalconer@worldnet.att.net) Available for consulting/temporary embedded and systems. <http://cbfalconer.home.att.net> USE worldnet address!
Reply by ●May 18, 20042004-05-18
> 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?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 by ●May 18, 20042004-05-18
On Tue, 18 May 2004 14:25:57 -0400, rickman <spamgoeshere4@yahoo.com> wrote:>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?Take the case for foil. The target area is the "trunk" of a human and is covered by a conductive vest. Note that fencing is an "explosive" sport, and humans sweat - I certainly drip and have to wear a headband. The outside of the vest can be damp. In order to prevent very light touches causing a score, the switch in the tip of the foil must open (normally closed). The weight required to open this switch is tested in competition. One side of this switch is the foil itself, which is normally ground. Sabre is similar, and in epee the target is the whole body, there is no conductive vest and the switch is normally open. In competition fencing the piste (floor) is copper mesh, usually a paper-making by-product. The tip of the weapon can touch the other tip ground (piste/weapon) target area (vest) non-target area The switch can be closed or open. The problem area with a wireless system is in discriminating these regions reliably, while maintaining good timing discrimination. Fencing is fast enough that discrimination and decision must occur within a few milliseconds, and bias from one side to another must not occur - fencers *will* notice it. I'm glad this topic has raised some interest - I'd really like to get rid of the spring-loaded spools: I had to retire from a competition after one failed and I spent the next morning in the hospital emergency department. Stephen -- Stephen Pelc, stephenXXX@INVALID.mpeltd.demon.co.uk MicroProcessor Engineering Ltd - More Real, Less Time 133 Hill Lane, Southampton SO15 5AF, England tel: +44 (0)23 8063 1441, fax: +44 (0)23 8033 9691 web: http://www.mpeltd.demon.co.uk - free VFX Forth downloads
Reply by ●May 19, 20042004-05-19
> I'm glad this topic has raised some interest - I'd really like > to get rid of the spring-loaded spools: I had to retire from > a competition after one failed and I spent the next morning > in the hospital emergency department.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 by ●May 19, 20042004-05-19
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