What are these four alternatives to GPS positioning that armies are developing around the world?

Communication and navigation have always been at the heart of military manoeuvre, so as to coordinate the action and movement of distant units. From summary maps, smoke signals and flags used since antiquity, armies have evolved towards increasingly efficient and precise systems, capable of bringing about the expected effect at the desired moment, and thus multiplying its effectiveness.

In the field of navigation, the invention of the Global Positioning System or GPS in the early 70s, based on a triangulated position signal from at least 4 satellites moving 20.000 km above the earth, and on the precision of the new atomic clocks, represented a considerable revolution in the conduct of military actions initially, then in the emergence of precision weapons also using this signal to reach their target with metric precision.

GPS positioning having become a key component for armies, it was foreseeable that other countries, or groups of countries, would also develop similar solutions. This was the case with the Russian GLONASS system which entered service in the mid-90s, the Chinese BeiDou system from the early 2000s, and the European Galileo system from the mid-2010s.

Indeed, controlling all of the technology, and in particular the satellites themselves, allows countries, and therefore their armies, to restrict its use or accuracy for other operators, or even to employ variations more precise and more resistant to jamming, as is the case of the GPS signal used by the American armed forces and their allies of the 5 Eyes.

Above all, many of these countries undertook to develop capabilities aimed at depriving the adversary of the use of their own systems. China, but more Russia, have thus developed several technologies to opacify a space given to the signal by the use of intense electromagnetic jamming, but also to reduce its precision, by using parasitic signals generating a drift of the receivers, this can be counted in kilometres. We then speak of spoofing.

While, as mentioned earlier, the United States has developed variations of the GPS signal that are more resistant to jamming and spoofing, secondary users generally do not have them. This explains in particular the reports of a certain lack of effectiveness of the Ground-Launched Small Diameter Bombs or GLSDB rockets used by the Ukrainians in recent months.

In fact, although satellite positioning systems are now found in the vast majority of modern weapon systems, the world's major armies have also undertaken to develop alternative positioning solutions to GPS, beyond inertial navigation. , allowing them to operate with precision above or in a space for which the signal would be inaccessible, or inconsistent, without returning to the famous triptych 3C: Map, compass and stopwatch, effective, but otherwise complex and difficult to implement .

These technologies are now 4 in number: celestial navigation, assisted visual navigation, navigation by signals of opportunity and magnetic navigation.

1- Celestial navigation versus GPS

Stars, whose trajectory is known and predictable, have been used for navigation since the dawn of mankind, when the first men understood that the sun rose in the same place, and set in the same place every day, at least in the perception of the time.

During antiquity, the stars were frequently used to locate and navigate, especially on the seas, using basic instruments that gave birth to the Astolab and then, many centuries later, to the sextant.

This technology, which may seem archaic and imprecise at first glance, is nevertheless used today intensively and very precisely for space navigation, whether it be satellites, probes or space vehicles. Above all, it is implemented by most strategic ballistic missiles to ensure the transit and precision of strikes.

Basically, using a sky map, a stopwatch and a tool to calculate the elevation of the stars, it is possible to obtain a very precise position on the whole planet, and even beyond. However, it is not devoid of certain limitations, the first and most obvious of which is its dependence on nebulosity to be able to aim at the stars used to establish position.

If, once combined with modern technologies, it proves effective for devices operating at high altitude, for which the weather is very rarely a factor, it quickly degrades as altitude decreases, making it a secondary tool. effective, for example to validate the data received by the GPS, but whose effectiveness cannot be guaranteed over time.

A solution to this problem has been developed in recent years, based on the detection of X-rays emitted by known pulsars from the celestial vault. If, theoretically, this technology should make it possible to overcome the problems of nebulosity, its precision, today, is still insufficient, of the order of 5 km, for an operational military use, apart from space navigation.

2- Assisted visual navigation or odometry

Until recently, fighter pilots conducting low altitude penetration missions employed, as previously stated, a method based on an accurate map, compass and stopwatch, as well as a good deal of mental arithmetic.

The rest of this article is for subscribers only -

Full access articles are accessible in the “Free Articles” section. Flash Articles are open in full version for 48 hours. Subscribers have access to the Analysis and Summary articles in full. Articles in Archives (more than two years old) are reserved for Premium subscribers.

- 15% on your subscription Classic or Premium (monthly or annual) with the code Homecoming23
Until September 30 only!