Kitajski domači GPS zdaj deluje popolnoma

The Chinese version of GPS, called BeiDou, was declared fully operational on Friday 31 July with great fanfare in a ceremony attended by President Xi Jinping. These Global Navigation Satellite Systems (GNSS), borne out of cold war necessities for America and the Soviet Union to launch accurate nuclear strikes rapidly are thankfully today focussed more on Uber arrival times and Pokemon Go gym takedowns. But why do countries choose to build rivals to the perfectly good USA’s Global Positioning System who’s very acronym – GPS – has become completely synonymous with any general reference at all to an electronic device showing a position on a map?

Economics

In the current peacetime climate the most important benefits of GNSS are economical. Estimates of the economic impact of a sudden loss of GNSS vary, but it is certainly of the order of $1B per day to the USA and a similar figure across the EU. This is because of the sheer number of facets of modern society that have become dependent upon GNSS. There are the obvious areas like aviation, shipping, road transport, etc where navigation using GNSS provides efficiencies and automation. Lesser known sectors that are critically dependent on GNSS availability are telecommunications, the finance sector, and even the electrical power grid. These sectors all make use of the fact that GNSS receivers can calculate the exact time, as well as exact position. Knowing the exact “true” time is critical to synchronising radio transmissions, or declaring the exact order of stock market trades at the millisecond level, or in maintaining a common phase for all substations across the electrical power grid. Since the loss of these delicate signals from GNSS satellites would cause such a huge impact to the economy of a first world country, it is no surprise that global powers like China have decided that they cannot rely on foreign sources of these signals to always be available to them.

Availability and performance

Relying on a different country’s positioning satellites means that you are of course making use of a system that is not necessarily tailored or optimised for your needs. The GPS Wide Area Augmentation Service is a geostationary satellite parked directly over USA that broadcasts correction data to GPS receivers to reduce the errors caused by atmospheric perturbations from around ten metres to around one metre. China have embraced this idea of tailoring their own GNSS too, using a mixture of satellite orbit types, including some geostationary above China, to ensure that while Beidou provides accurate positioning anywhere on the planet, it is specifically tailored to providing maximum performance over home soil.

Obramba

The Defence arguments behind the needs for a home-grown GNSS have evolved in various ways over the decades. The two first GNSSs, the American GPS and Russian GLONASS, were developed for a very specific clear purpose – to aid nuclear submarines and bomber aircraft in the rapid deployment and delivery of nuclear weapons, and the very first receivers were too large for a single person to lift them. Fast forward a few decades and fingernail-sized GNSS chipsets are a critical requirement of all modern warfare platforms for a great swath of reasons, from battlefield situational awareness and precision-guided munitions to synchronisation of military radio communications systems. Originally GPS was designed in such a way that the open “civilian” signal available to the public was required to allow a military receiver to lock on to and start using the military encrypted signal, which then provides higher performance and protection against hacking or “spoofing” of the positioning signals. This dependence of the military signal initialisation phase on the availability of the simpler civilian signal gave other countries some reassurance that the USA would never turn off the open civilian signal or block its availability in a warzone, but over time the USA has changed the encrypted military signal, and the capabilities of receivers such that this requirement of the military signal on the civilian signal no longer exists. This means that in principle the USA could actually employ local jamming or spoofing of its own civilian signal in a warzone without disrupting its own military signals in any way. This has therefore also been a factor in accelerating the completion of the Chinese BeiDou GNSS, and the European Galileo GNSS.

Kaj drži prihodnost?

Kitajska ima presented plans to lead the world in robust Positioning Navigation and Timing capabilities by combing the fully operational BeiDou system with signals from Low Earth Orbit satellites, terrestrial low frequency radio signals, and future quantum-based navigation systems. Such multi-sensor systems are the key to robust and highly-accurate positioning and timing systems, and the Chinese proposals exceed those formally laid out by other nation. It may be the case that in another decade’s time it is no longer GPS, but instead BeiDou that is the expression we will all be casually using to refer that little blue dot on our smartphones.

Source: https://www.forbes.com/sites/ramseyfaragher/2020/08/01/chinas-homegrown-gps-is-now-fully-operational/