By David Hambling, technology expert
Satellite navigation has become such a part of everyday life that we often fail to appreciate how much we use it. This reliance can create huge problems for the military, especially if the magic which tells us where we are, suddenly disappears.
The vast majority of satellite navigation is currently provided by the Navstar Global Positioning System (GPS), a constellation of more than 30 satellites operated by the US Air Force.
Originally intended for military use, it was opened up to civilians in the 1980s and has since become ubiquitous, with more than 14 million sat navs in the UK alone.
While military forces often train in ‘GPS-denied’ conditions without sat nav, it tends to play a major part in normal operations.
A bomb with GPS guidance can hit within a few metres of a target from any range and in any weather.
Most US bombs now have JDAM (Joint Direct Attack Munition) guidance kits – more than 260,000 have been delivered.
The RAF has the 500-pound (230-kilo) Paveway IV with laser or GPS guidance, as well as the Storm Shadow cruise missile which uses GPS in combination with inertial navigation and terrain following.
GPS guidance allows British Army’s GMLRS artillery rockets to hit pinpoint targets from 70 km away. There are even GPS-guided mortar rounds.
Jamming is a major issue for GPS.
The signal is the same strength as a car headlight 12,000 miles away, so can be swamped by cheap, low-power jammers a few miles away. Such jammers are readily available on the internet.
Truck drivers have jammers to prevent the use of a vehicle out of hours being spotted, and thieves use them to prevent stolen vehicles being tracked.
Military GPS includes anti-jam modules and other hardware which makes it far more resistant than the civilian version. However, military-grade jammers are getting more sophisticated.
In Syria, Russian GPS jammers have reportedly prevented some drone operations over Syria.
The truck-mounted Krasukha-4 is claimed to block out GPS over a wide area, and some analysts have expressed concern that Russia is ‘winning the electronic war’.
The latest Russian development is an electronic warfare aircraft called Porubshchik 2 which is claimed to be able to “disable enemy satellites that provide navigation and radio communication.”
This capability would probably only be used in an all-out war, but if the description is accurate it would make any devices relying on GPS useless.
GPS can be lost in other ways too.
It is still a US military system and can be selectively turned off to prevent it being used in a regional conflict.
The Indian military found that GPS was blocked in the Kargil region during a dispute with Pakistan in 1999.
An awareness of this reliance has led Europe to develop the alternative Galileo satellite navigation system; the Russians have their GLONASS and the Chinese have their own, known as Beidou.
Galileo is now coming into use after fifteen years of development and will be fully operational in 2020.
Because of Brexit though, the UK now looks like being excluded from Galileo, and the government is looking at alternatives. One of these would be a new, British-owned satellite navigation system.
This would cost something over £3 billion and take about five years.
Even when satellite navigation functions perfectly, it can cause unexpected problems.
Recently, hackers have used GPS data from fitness trackers and smartphones to locate secret military bases in Afghanistan and Syria.
Personnel at these bases were using the devices to record their exercise, unaware that this allowed the software’s vendors to see their running route – which may be a location which was not supposed to be disclosed.
American troops are now banned from using any geo-location software on deployment.
Satellite navigation has become an essential utility for everyday life. The question is how effectively we can fight wars if it gets taken away.