// Our terrifying reliance on GPS, and the need to develop a ground-based alternative- Part1 ~ EDUCATION & TECHNOLOGY

Tuesday, 14 April 2015

Our terrifying reliance on GPS, and the need to develop a ground-based alternative- Part1

GPS satellite, artist render

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The Global Positioning System, or GPS, has — somewhat surprisingly — found itself at the heart of modern civilization. I don’t think anyone predicted how significant GPS would be today, just 14 years after it was made freely and globally available to civilians and commercial operations in 2000 — but hey, it happened, and there’s no going back. There is no doubt that the ubiquity of GPS across all areas of civilian, commercial, and scientific endeavor has improved the quality of life for billions of people. From self-driving cars to clock synchronization, from geo fencing to earthquake prediction to finding a safe walking or cycle route home, GPS really is one of the most vital services. It is a little bit scary, then, that GPS can very easily be jammed by terrorists or other nefarious actors.

GPS jammers

Because GPS ultimately relies on very weak radio signals being beamed to you from about 12,600 miles (20,200 km) above Earth, it’s very easy for GPS to fail or be otherwise disrupted. Being underground is one obvious example, but just walking around the streets of a high-rise city can be pretty tough for GPS.
You can buy a battery-powered GPS jammer online for less than $100
You can buy a battery-powered GPS jammer online for less than $100
It’s also very easy to proactively disrupt GPS with a jamming device. Because the signal is so weak, and because the frequency used by GPS is very well known (1559 to 1610MHz), it’s very easy to build a device that blankets an area in RF noise, smothering the GPS signal. (In case you were wondering, picking up a GPS signal is like trying to spot a 25-watt light bulb from around 10,000 miles away.) There are cheap, pocket-sized GPS jammers that you can buy online that provide a jamming radius of a few meters — but of course, with a little technical knowhow, it would be fairly easy to build a larger device that blocks an entire street or city from using GPS. (Those pocket-sized jammers are regularly used by truck drivers and couriers, incidentally, so that they can evade the ever-watchful gaze of HQ.)

When GPS fails

Because so many different technologies and endeavors are backed by GPS, the consequences of GPS failing or being jammed are wildly varied. For someone on foot, a GPS outage might simply be an inconvenience that forces you to stumble around for a little longer in your search for the highest-rated indie coffee shop on TripAdvisor. For a self-driving car, or perhaps an ambulance driver trying to find someone’s house, the repercussions of GPS failure are a little more significant. For a seafaring vessels, especially the larger cargo ships, a loss of GPS can mean a complete loss of control — which is a problem if you’re approaching the dock at high speed, or if you end up being stranded in the middle of the ocean.
And, of course, you really don’t want to lose GPS if you happen to be barreling through the sky at hundreds of miles an hour — like if you’re an airplane, or a cruise missile perhaps.

So, of course, you need a GPS backup

Constellation GPS
The orbiting constellation of GPS satellites
The driving force behind the creation of the GPS — and the more recent Russian GLONASS, Europe’s Galileo, and China’s COMPASS — is that you can provide global coverage with a constellation of just two dozen satellites. GPS consists of 32 orbiting satellites, ensuring that (generally) you can see nine satellites at any given time — more than enough to get an accurate location fix (the minimum is four). Because of the distance between us and the satellites, though, the signals are very easy to jam (and as an aside, they’re not very good for calculating altitude, too).
A ground-based system would be much more flexible and accurate than GPS — but the trade-off is that you need to blanket the Earth in hundreds or thousands of transmitters, which are expensive to build, hard to maintain, and in some cases just plain inconvenient (how do you monitor the southern Indian or Pacific oceans, for example?)
Still, the difficulty of building a ground-based global positioning system is far outweighed by the catastrophe that would result from an unexpected attack or prolonged outage of GPS — which is why some nations are now taking a serious look at ground-based alternatives to GPS, just in case a worst-case scenario does actually occur.


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