In 1957, the Soviet Union put the world’s first artificial satellite, Sputnik I, in orbit. Close on the heels of the historic launch, two American physicists, William Guier and George Weiffenbach, started monitoring Sputnik’s radio transmissions. The scientists realised they could track the satellite’s paths based on the Doppler effect.
Many Global Navigation Satellite Systems (GNSS) exist today, such as Europe’s Galileo, the Indian NAVIC, and the Chinese BeiDou. The most widely used among these systems has been the United States’ Global Positioning System (GPS). Today, GPS has found its way into most fields humans operate in, ranging from navigating family vacations to military crafts and guiding water and fertiliser application in precision agriculture.
A basic GNSS service provides location information up to 7.8 metres 95 percent of the time, anywhere on or near the Earth’s surface by making use of a constellation of satellites (31, for GPS) that carry atomic clocks that accurately tell time—within a few dozen nanoseconds. Each of these GNSS satellites emits signals to receivers that determine location by computing the difference between the time a signal is sent from these satellites and when it’s received. Because radio waves travel at a constant speed, the receiver then uses the time measured to calculate distance from each of its satellites. Aircraft, space shuttles and submarines etc use GNSS to navigate. In a standard car GPS, the GPS receiver plots the car’s changing location on an electronic map (using satellite data). Although most GNSS systems are pretty exact, some might be more accurate than others—e.g. The Indian NavIC is reportedly more accurate than GPS systems.
A jam here and a spoof there
However, GNSS systems fall short due to certain obstacles. For example, jamming and spoofing. Let’s first look at how jamming works. Jamming may happen accidentally at times. Gravity can throw GNSS satellites slightly out of orbit. Other than this, the environment around us, i.e. trees, mountains, buildings, can distort radio waves and GNSS networks. Jamming could, however, be done on purpose. Personal privacy jammer is a good case in point. These are illegal in most places—including India, where jammers can only be procured by defence forces, the police, jail authorities and central government security agencies. PPJS jammers are responsible for a whopping 85 per cent of vehicle thefts in Mexico. The second type is wide-area jammers usually used for protection against GNSS-guided attack weapons like drones and disrupt GNSS across large areas.
Military jammers can derail systems across hundreds of kilometres. These can be highly disruptive and are usually used in war zones. In Seoul, South Korea’s capital city, GNSS outages — reportedly due to jamming from North Korea — are a huge problem. In China, an electronic warfare unit with four counter space jammers was deployed 60 km from Arunachal Pradesh’s border, allegedly to jam Indian communication satellites. Other obstacles, such as spoofing, can also prove harmful despite being subtler. Spoofing involves fake GNSS signals that confuse navigation systems.
Why so glitchy?
Why are GNSS systems so easy to jam or fraud? GNSS satellites broadcast time accurately but are solar-powered and send signals using 50 or fewer watts— equivalent of the energy required to power a refrigerator light bulb. Due to this, GNSS systems can be glitchy and vulnerable to interference. This is a significant problem considering the wide use of GNSS systems, especially in a military environment. Moreover, GNSS systems are also of utmost importance in sensitive jobs such as coordinating telecom networks and electricity grids, time-stamping financial transactions, and overlooking the traffic of data and information in and out of centres. This further exacerbates hindrances within GNSS navigation systems. So, GNSS Jammers (the deliberate ones) usually work by sending radio signals with the same frequency as a GNSS device. Through this, the GNSS device would receive interfering signals and thus be unable to determine its position. Spoofing, on the other hand, requires manipulation of these signals to create different results.
What can be done?
Jammers, while mostly illegal, are widely used and can have severe collateral effects. Thousands of lives depend on GNSS navigation systems—ranging from aeroplane passengers to phone networks to stock exchanges. Many transactions performed automatically by computers require time stamps provided through GNSS antenna. This time-clocking ability supplied by these systems is also imperative to powering electric grids, which rely on ultra-precise synchronisation to prevent blackouts. Spoofing has historically been a common tactic to divert surveillance drones from drug cartels and could lead to stock market disruptions like the flash crash of 2010.
Today, GNSS systems are used for geolocation and time-stamping purposes. With the increasing use of technology and the fast-paced nature of present-day operations, GNSS systems seem to be going out of fashion.
Satelles, an American company, has been using Iridium satellites. These use 66 satellites—as opposed to GPS’ 31—orbiting at an altitude of 800 km to re-broadcast encrypted time data—and then location data like a GNSS system–sent from ground-based high precision clocks. This system possesses much stronger signals than GNSS ones, thus shortening the effective range of jammers.
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I am an economics undergrad who loves drinking coffee and writing about technology and finance. I like to play the ukulele and watch old movies when I'm free.