GLONASS, the Russian response to GPS

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GLONASS, the Russian response to GPS
NAVSTAR GPS was the first satellite-based navigation system that took over the world. When the first US satellites found their lonely homes on orbit, the Russians responded in style. They create their own navigation system, called GLONASS, that now offers similar services and precision as GPS. Which devices are the most precise ones then? The ones that combine both GPS and GLONASS data.

Space history

The first hours working on the GLONASS system were logged in 1976. The project called Globalnaya navigatsionnaya sputnikovaya sistema was a baby of the Defense Ministry of the USSR, Russian Academy of Sciences and the Soviet Navy. The first testing satellite was launched 6 years later, only 4 years after the first GPS satellite.

The system was completed in 1995, but because of the bad economic situation of Russia, especially after the dissolution of the Soviet Union, it wasn’t used. The rebirth of GLONASS began in 2001, and in nine years the engineers managed to rebuild and update it so that it covered the entire Russian territory. From 2011 it is possible to use GLONASS for navigation worldwide.

GLONASS vs GPS

The cosmic segment of GLONASS is comprised of 24 satellites called Uragan. While GPS employs 32 satellites following six different orbits at 20 200 km above the ground, Uragans see the Earth more up close, circling on three different space routes “only” 19 100 km high.

Thanks to this, each of the GLONASS satellites completes one rotation around our planet in 11 hours and 15 minutes, which is 43 mines shorter than their American counterparts. The main advantage of the Russian satellites is that they are very stable and don’t require additional corrections. On the other hand, they have a way shorter lifespan than the GPS satellites.

GLONASS makes friends

The ground segment is run by the main system control center in Krasnoznamensk and comprises of five Telemetry, Tracking and Command centers, two Laser Ranging Stations, and ten Monitoring and Measuring Stations. Most of them are located in Russia and Tajikistan.

But GLONASS thinks big and wants to have stations also abroad, so in 2013 they set up the first station in – you might not believe it – Brazil! And it looks like the Russian engineers like the hot weather (or maybe just the perfect geographical position) of Brazil because, in 2018, they announced the opening of the fifth Brazilian GLONASS station! To improve its accuracy, more stations are being built in other countries of the southern hemisphere, for example in Indonesia.

Frequency modulation

Unlike GPS, GLONASS transmits data using frequency modulation, which means encoding the information by varying the instantaneous frequency of the wave. This makes the system more demanding in terms of the bandwidth used and slightly changes the requirements for the signal receiver. However, the resulting positioning accuracy is comparable in both competing systems.

GPS + GLONASS = unlikely cooperation

Both GPS and GLONASS are quite precise but sometimes just not precise enough. Today, many devices that need the most precise information about its position are using both the American and Russian systems at the same time.

The reason is that increasing the number of satellites boosts also the precision of the data. If you use both systems, the accuracy increases by about 15 to 30 percent. This makes the biggest difference when the device is in a place with a limited view of the sky (jungle or a city with many skyscrapers) or in places far away from the equatorial.