The GPS is a time machine

The Global Positioning System (GPS) isn’t just for navigation. Most modern technologies depend on it for having a single precise system of telling time


The Global Positioning System, or GPS, uses passive range-finding technology to pinpoint your exact position on the globe by calculating the time it takes for a pulse from its satellites to reach your receiver. Photo: AFP
The Global Positioning System, or GPS, uses passive range-finding technology to pinpoint your exact position on the globe by calculating the time it takes for a pulse from its satellites to reach your receiver. Photo: AFP

Last year the world turned in on itself. From Brexit to the US election, countries around the world rejected globalization and chose to focus on themselves and their own. But globalization isn’t something you can turn off at will—at least not without altering the fabric of modern civilization. We are, today, more dependent on each other than ever before and any attempt to move further apart will literally set us back decades.

And at the heart of all this, is time.

In medieval Europe, each village had a single, usually imprecise clock, on top of a high tower in the town square. This was the only timepiece in the entire village, and it made no difference that it told time differently from the clock tower in the next village because, everyone worked at their own pace—producing entire products on their own, without the need to coordinate with anyone else.

ALSO READ | Isro launches 104 satellites in a single mission to create world record

The moment machines entered the production process, coordination became critical. Factories had to ensure they had workers at every station on the assembly line before they could start production. They, themselves, had to adhere to timetables that fed into larger national schedules—such as that of the transportation systems they relied on for raw materials. Ultimately, it was the railways that forced clock towers across nations to synchronize themselves to ensure that whenever a train pulled into the station, passengers were waiting to board.

This was the genesis of punctuality and our modern notion of time.

Today timeliness is core to everything we do. From the alarm clock that wakes us up in the morning, to the activities we plan through the day, the conference calls we schedule with colleagues around the world and literally every other aspect of our daily routine. None of this would be possible without the existence of a common and coordinated system of telling time.

But that is just the tip of the iceberg. Our dependence on time runs far deeper than is immediately apparent. Many of the complex networked technologies that we take for granted today depend on precisely synchronized time to function.

Mobile telecommunication networks, for instance, use multiplexing to maximize bandwidth, combining multiple voice signals into one and carrying them across their network till they can be separated and recombined into the intelligible sounds that emanate from the receiver’s device. In order for this to work, each telecom switch must be precisely synchronized with every other as an error of even ten microseconds can have catastrophic consequences across the network.

Another example of this is the SCADA systems that modern electricity grids use to monitor fluctuations on the network. As grids grow more complex they, in an attempt to avoid the sorts of massive grid failures that North India experienced in 2012, have begun to deploy synchrophasor technology that gathers live data from every node on the network and analyses it in real-time. Synchrophasor need to be precisely synchronised—if the timing of even one synchrophasor is off by more than 26.5 microseconds, the entire grid could collapse.

Most modern technologies depend on having a single precise system of telling time—that works everywhere. The technology that most of the world turns to for this is GPS—the global network of satellites that we associate, more commonly, with navigation. GPS uses passive range-finding technology to pinpoint your exact position on the globe by calculating the time it takes for a pulse from its satellites to reach your receiver. Its accuracy depends on time computations so precise that a mistake of one-millionth of a second translates into a distance error of over 300km. As a result, GPS is the most accurate, perfectly synchronized timing system on the planet—that is, to boot, accessible, free of cost, from anywhere on earth.

Over the years this time-keeping feature of GPS satellites has been incorporated into almost every critical technology infrastructure we know—from telecommunication systems to global power grids and complex financial trading networks. Although no one really talks about it in these terms, GPS is probably modern civilization’s single point of failure. It is worth mentioning, at this point, that GPS is exclusively owned and operated by the US Department of Defence which spends over a billion dollars a year keeping the satellites in the sky and the monitoring stations around the globe, functioning.

As the new US administration makes it increasingly clear that it is going to put America first, there is widespread consternation about the increasing distance that the US seems to be placing between itself and the nations of the world. But as tempers rise, we’d do well to remember that much of modern life depends on the continued benevolence of the US in maintaining and improving GPS—and in keeping it accessible from everywhere, by everyone, for free.

Rahul Matthan is a partner at Trilegal. Ex Machina is a column on technology, law and everything in between.

His Twitter handle is @matthan.

More From Livemint