Underwater Timing Gate - Optical or Sonar

For optical -The leading (or trailing) edge of a swimmer changes dramatically. How do one distinguish between a single finger and the effect caused by waves?

Best of luck with your project. Are we going to get yet another set of records?

Thanks Hendrik, you have made a valid point. Only time will tell. I'm thinking the water will be pushed upwards ahead of the swimmer and, given that the timing is usually taken as the first body part past the point, if the system can pick up the leading finger so be it. The trick will probably be the depth at which the 'gate' is set and getting the timing/resolution of the trigger response right.

Cheers

You say the pool(s) will be 50m long, indoors or out... so, this is not for "Open water" events.

Whateverhappenedto a simple "Tap" pad at either end, thus mandating a touch-of-accuracy on the swimmer's part (along with the power of their strokes)...?

Not trying to insinuate that perfection can't be improved-on, but, as already implied, attempting to use a "beam" of one type or another will most certainly open opportunities for heated arguments someday. You know ... "My buzzer didn't fire til it saw my shoulder, where that other guy's detected his fingertip"...

But how does one argue an actual touch...? Also, there are always video replays for who-touched-first, if a swimmer says their touch-pad wasn't as sensitive as the other person's. On top of all that, timers can be sync'd with a video stream, with the recording documenting elapsed times to the thousandth of a second.

My own impression is that you're steering the wrong direction for improvement in this arena ... but, I could be ALL WET !

Best Regards ~

Hi NDT_Tom,

Thank you for your comment. The purpose of the timing gates are for a training aid. 4 gates will be positioned along the pool to provide immediate feedback to the swimmer of the suitability of their pace with respect to a predetermined schedule and to provide more detailed data for coaches than is available through lap times . Timing gates of varying types are already in use for this purpose at many national institutes of sport but are very expensive. It is my intention to build an affordable set to use in sports science research.

Cheers

"Aha"... for training purposes! ok ... one swimmer at a time, or multiples?

If only for a single candidate at a time, they can SEE a series of highly-contrasting stripes on bottom, yes...? and, they can HEAR (or, if deaf, feel pulses) ... sounds or pulses that might take a smidge of practice to learn, analogous to a simplified Morse code...?

1st sound: High pitch = "fast", Low pitch = "slow"...

2nd sound: Single = "slightly" ... Double = "moderately" ... Triple = "hugely!"

How much of a 'difference' might there be? Also, does anyone make an "in-the-ear" Bluetooth-sort of earphone, so the swimmer can clearly hear what a coach is speaking into a "Bullhorn-type" of transmitter (without unnecessary decibels)??

So many options ~ where do you begin? Can't wait to hear what you come up with. Our divers (commercial/oilfield) haven't gone "wireless" yet with comms. Kinda pointless: the cable is insignificant, bundled with the air/gas/pneumo hoses and lifeline (strength-rope).

Wishing you success! ~