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How a Musician Used Beats to Build a Better GPS

How trying to tie sounds to place led to a breakthrough in geolocation

3 min read

A satellite view of Europe at night, showing cities and towns lit up by lights.
Image credit: Eric Fischer // CC BY 2.0
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By trade, Australian Nunzio Gambale is a musician. But in 1997 he was working with engineer David Small on what started as a minimalist project: a location-based guide for Canberra, the capital city of Australia, using satellite GPS. The concept was simple–visiting a particular spot would trigger an audio file, such as commentary pointing out landmarks.

But there was a problem. “GPS signals today are very unreliable–or totally nonexistent–in a huge number of modern settings, from crowded downtowns to anywhere indoors,” said Gambale. While space-based GPS covers the world over, the satellite signal is weak in certain spots, its power equivalent to a car headlight well over 12,000 miles away. It is blocked by walls or other obstacles, leaving the coverage full of holes. Large buildings also reflect radio waves, producing an effect called multipath which can make one’s apparent location jump around by hundreds of feet.

“It might surprise most people if they dial 911 for emergency services with their smartphone in a dense urban area, the best they can reliably hope for is to be located to within one or two city blocks,” said Gambale. He and Small wanted something better than GPS. In the end, they built it themselves–founding a company called Locata to market a powerful new technology that beats satellite navigation hands down.

Previously, researchers have looked at supplementing the GPS signal with high-powered transmissions from ground-based pseudosatellites. The problem is maintaining synchronization. The satellites get their absolute reference time from a master atomic clock in Colorado Springs in the United States each time they pass over it. Ground-based transmitters cannot do this, and their synchronization slips. Even with atomic clocks, ground transmitters become unusable in a matter of days.

Gambale and Small solved that problem using a musical technique. Unlike GPS, which resembles an orchestra following the beat marked out by a conductor, Locata transmitters pick up the beat from each other. “The Locata transmitters play together like a band”¦ They do not need or use any external clock or conductor to synchronize themselves,” said Gambale.

Each new transmitter picks up the signal from the other transmitters and joins in. While initially it is slightly out of time with them, the delay allows it to calculate its positon. It then adds in the appropriate delay and adjusts its timing. The new transmitter is synchronized to within a nanosecond, and records a precisely-known location. The process is continuous, so the ground stations maintain perfect synchronization without any clock at all. As with a band, some players can drop out or new ones can join in without affecting the performance.

The idea sounds obvious enough now, but previously nobody believed clock-free navigation was possible. “Almost every expert we approached said we were crazy,” said Gambale. “We were openly mocked when we went looking for development funding.” Gambale sold everything to fund development, including his music business. His belief in Locata paid off.

Now, “The naysayers are eating crow,” as Gambale put it. Locata currently provides highly accurate navigation in places where GPS cannot reach. The area covered can be as small as a building or as large as a city. For example, in open-pit gold-mining, drills have to be positioned precisely to strike rich veins. The depth of the pit means that enough satellites are not always visible overhead to get an accurate fix. At Newmont’s Boddington gold mine GPS navigation is only available about 92 percent of the time. Delays are expensive, costing over $1,000 an hour. Boddington became the first mine to adopt the Leica Jigsaw Positioning System, which incorporates Locata technology as well as GPS. “The system at Boddington paid for itself in 90 days,” said Gambale.

The U.S. military is another early adopter. Locata technology is being installed at the U.S. Air Force’s White Sands Missile Range. It will be used in situations where GPS is jammed to provide a truth reference, the standard by which other navigation systems will be judged. In contrast to the small local area covered in a mine, the White Sands system covers some 2,000 square miles. It is still highly accurate, providing a fix to within one foot. It’s unusual for the Pentagon to purchase foreign technology, especially when it comes to navigation–after all, the Pentagon effectively owns the multibillion-dollar GPS satellite constellation. Locata’s success in this area is a sign of things to come. “This contract makes it clear you are witnessing the arrival of one of the most important technology developments for the future of the entire positioning industry,” said Gambale.

The first generation of Locata receivers are expensive and bulky–briefcase-sized–but as with GPS devices these may shrink rapidly. Gambale said that in the next year there will be a credit-card sized version costing a few thousand dollars. Chip-scale technology will follow. He even bullishly predicts smartphones running Locata technology alongside GPS within four years.

This could enable a whole new generation of location-based indoor services. If you want to find the way to Platform 18 or Meeting Room K, meet someone in a crowd or just locate the peanut butter in the supermarket, there could be a Locata-based app to help you. And for the user it has an advantage over other indoor navigation systems. “Locata is the only high-precision technology I know of which will work in phones in cities and still allow the user complete anonymity from tracking,” said Gambale.

Improved navigation will absolutely be a key enabler for self-driving cars, but the real breakthrough area may actually be for robots indoors. One of Gambale’s current projects is an automated warehouse system. Current indoor navigation approaches generally rely on laying markers on floors or walls for robots to follow. In the future, the whole world could be moving to a new beat, one that is synchronized by Locata transmitters playing in time with each other.

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How We Get To Next was a magazine that explored the future of science, technology, and culture from 2014 to 2019. This article is part of our Fast Forward section, which examines the relationship between music and innovation. Click the logo to read more.