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Sonar alarm system detects kids in the pool

The Dolphin Alarm receiver unit (top left) and the wristband (top right)
The Dolphin Alarm receiver unit (top left) and the wristband (top right)
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The Dolphin Alarm system
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The Dolphin Alarm system
The Dolphin Alarm receiver unit (top left) and the wristband (top right)
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The Dolphin Alarm receiver unit (top left) and the wristband (top right)

If you have a small child and a swimming pool, then it's at least a little likely that you may sometimes worry about said child falling into said pool. Well, it was with that concern in mind that British electrical engineer John Barstead created the Dolphin Alarm.

Here's how it works …

When small children who have no business going into the pool on their own are out playing near it, they wear a special wristband. If they should fall in, the wristband will generate a three-tone sonar signal as soon as it's immersed in the water.

That signal will be detected by a hydrophone contained within a receiver unit that floats in the pool. When that happens, the unit will emit a 131-decibel alarm. It will also transmit an alert to an indoor remote unit located up to 150 m away (170 ft), which will likewise sound an alarm of its own.

The Dolphin Alarm system
The Dolphin Alarm system

While there are other child-in-the-pool alarms, most of them are wave-activated and have to be shut off when other people are using the pool.

Barstead and his team are currently raising production funds for the Dolphin Alarm, on Kickstarter. A pledge of £143 (about US$201) – which is 50 percent of the planned retail price –will get you a system, when and if it reaches production.

Sources: Dolphin Alarms, Kickstarter

6 comments
highlandboy
So how do you force children to keep the arm band on? Supaglue? Or better yet “wouldn’t it be fun to see Mum and dad come running? - I just have to put my wrist in a the water”. Great that people are trying ideas for such a problem, but still no replacement for good pool fences and constant supervision.
Nahor
Looks REALLY iffy: - Not a single image of the real product even though it's supposed to go to manufacturing next month. - They mention some accreditation, in particular "ANSI 2535.6". The only mention I can find online about that a poor OCR from the ANSI Z535.6 which does seem related to safety. If the accreditation is such a good thing, how can they get it wrong? - But then, Z535.6 is about manuals and instructions. Nothing critical, just pompous. - Similarly, AFNOR NF P90-307, looks to be related to "optical beam scanning", while this product is sonar based (although, maybe, some of the rules in P90-307 would apply to sonar) - In the timeline on the Kickstarter page, they say they had to remove an existing product from the market because of new US regulations => unsafe product? - Then two years later they moved to the UK. Coincidence or are they trying to work around those regulations? And even if all the above is wrong, are they really expecting kids to remember/want to put on the bracelet/belt every time they go near the pool? Wave-based devices at least don't have such a requirement. I don't know for you, but to me this feels more like a scam than a real (or even useful) product.
Craig Jennings
Really thought this was going to be a sonar version of a motion detection alarm.
Brian M
highlandboy - Hits it right on the head. Great that people are trying to protect kids this way, but this is not the solution. System needs to failsafe, this doesn't. Better to have something detecting movement in the water, which then triggers an alarm unless wearing a bracelet. So adults have to wear an ankle/wrist bracelet before taking a dip - Will also amuse said kids that mum/dad/big sister/brother are tagged!
ljaques
It's way overpriced at half retail. And it requires the child to put on the watchband device, so it's failure prone at best. I guess most of these items are overpriced: https://www.swimuniversity.com/best-pool-alarms/ I think I'd go with the subsurface disturbance alarm, which is less expensive. If you have small pets, put in a doggy ramp which allows them to walk out. Speaking of which, I think I'll start building them and selling them for $402 retail. I'll make a million!
Nahor
Looks like I was not the only one suspicious of that project. It has been suspended by Kickstarter.
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