Engineers develop an underwater phone: How it works and who it’s for

Back in the 1970s, divers jokingly riffed on Deep Purple’s “Smoke on the Water,” asking, “You managed to do it above, but what about below?” For decades, underwater communication remained elusive. Ships and submarines rely on radio signals, but radio waves don’t travel through water. Divers were left with hand gestures and guesswork. Now, that’s changing.

A team of Russian engineers from MIPT, Bauman MSTU, and Kosygin RSU has created a groundbreaking underwater phone that lets divers talk to each other. Project leader Dmitry Zatekin explained how it works in an interview with Komsomolskaya Pravda (kp.ru/daily/27675/5063752/).

Why Doesn’t Radio Work Underwater?

Water excels at carrying sound—whales and dolphins have long proven that. But humans aren’t sea creatures; regular speech drowns out underwater. Radio signals fare no better: standard frequencies fade fast, and long-wave options demand massive antennas and powerful stations—impractical for a diver’s gear.

Alternatives like ultrasound also fall short. Human ears can’t hear ultrasonic signals, and those waves struggle in the complex underwater environment.

How Does the Underwater Phone Work?

This device is compact and high-tech. Here’s the breakdown:

1. A diver speaks into a throat-mounted microphone.
2. A specialized algorithm filters out noise and converts the voice into a digital signal.
3. The digital signal travels through the water.
4. The recipient’s earphones decode it back into audible speech.

It reaches up to a kilometer, making it valuable for professional divers working on underwater structures or specialists in aquaculture. Future plans include adapting it for recreational diving.

Compact Powerhouse

The challenge was packing sophisticated electronics into a small, rugged device fit for harsh underwater conditions. Advances in single-board computers made it possible.

What’s Inside?

• A compact Arm Cortex-A76 processor, sipping just 15W.
• A streamlined OEM single-board computer, stripped of excess interfaces.
• An optimized neural network model for voice processing.
• A hydroacoustic modem using a piezoceramic cylinder.

Why Is Sound Transmission Underwater So Tricky?

Acoustic signals in water face a gauntlet of issues:

• Noise distorts the sound.
• Waves scatter and lose strength.
• Signal delays disrupt device sync.

Western systems often faltered due to lag—delayed signals confused receivers, breaking the link. Russian engineers tackled this with Chirp Spread Spectrum (chirping), a coding method built for tough conditions. It resists interference, reflections, and temperature shifts—crucial for underwater reliability.

A Game-Changer in Underwater Communication?

Still in testing, the tech has already won praise from pro divers. The sound is clear, it integrates easily into gear, and it supports multi-user chats.

Data speed is modest at 67 bits per second—enough for speech, not video. But that’s not the goal; it’s about enabling underwater conversation, not streaming.

For now, it’s too pricey for the mass market, but costs could drop. It might one day become standard for both pro and amateur divers, pushing underwater communication beyond gestures into new realms for ocean explorers.