Why Wireless Communication Underwater Can Be Difficult

Why Wireless Communication Underwater Can Be Difficult

A lot of our customers have questions about wireless signals in water. Number one on a lot of swimmers' wish list? Wireless earbuds! Right up there, though, is wanting to listen to music from their phone while swimming. It sounds so great and easy, right? If wires create drag, why have them at all? If I can listen to music with my phone in the pocket of my running shorts, why can't I swim with it in the pocket of my swim trunks?

As it turns out, though, more is getting in the way of this dream than just the lack of waterproof wireless headphones on the market. Here, we're going to take a quick look at why wireless devices haven't yet taken the world of swimming by storm.

A Little About Wireless Signals

The first thing to understand is a little bit about the frequency (or wavelength) of the wireless signals we've all become so accustomed to over the last few years. All wireless devices communicate by emitting and receiving radio waves. Bluetooth, WiFi, cordless phones, even garage door openers and other gadgets all tend to operate on the same frequency. (Here's an interesting article about why.) That frequency is 2.4 GHz, and it's a pretty high, meaning the peaks of the waves are closer together. 

Why Frequency Matters

Water interacts with electromagnetic waves (of which radio waves are a part), and the shorter the wavelength, the more water absorbs the waves. People have found some, frankly, pretty interesting ways to take advantage of this: microwaves, as their name implies, are extremely short. Water absorbs them so completely that microwaves are used to cook things in the common household appliance that goes by the same name.

Waves used in common wireless devices aren't that short, but they are pretty effectively stopped by water. As shown in one rather complex and visually dated lecture, 2.4 GHz signals are significantly degraded after just 1.4 cm. That means that with anything more than a finger's width between the transmitter and the receiver, your signal isn't going to get through clearly.

Implications for Swimmers

What this all means for swimmers is that the signal that comes so clearly from your router, or your phone, to your Bluetooth device? Isn't going to make it to you when you're in the water. It's just not; not without some ridiculously huge antenna sticking out of the water from your headphones. [sad trombone]

The Good News

The good news is that Underwater Audio has been working to find a way around those limitations, and to bring into the pool some of the features swimmers already know and love from their time out of the water.

Our line of Swim Kits for Apple Watch (shown here with Swimbuds) enable Bluetooth and wireless signals to operate at a close range between sending and receiving units. While wearing goggles, the Apple Watch is attached to the Clipi spring clip. The Apple Watch is then clipped to the goggles on the back of the head. Then the wired waterproof headphones are plugged into the Uku, which has been paired with the Apple Watch. The Uku is then clipped to the goggles on the back of the head right next to the Apple Watch, and the headphones are inserted into the ears. This proximity between sending and receiving units is what allows the music to flow interrupted into your ears.

The upcoming Delphin music player and Swimbuds Bluetooth headphones also work underwater for a similar reason to the Swimbuds Kit for the Apple Watch. After the two devices are paired together, the Delphin is clipped to the goggles on the back of the head, and the Swimbuds Bluetooth headphones are worn around the back of the head. They are close enough to each other that communication is able to be had between the two devices without cutting out.


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