Satellite navigation device

A satellite navigation device, also called a satnav device or GPS/GNSS device, uses satellites of the Global Positioning System (GPS) or other global navigation satellite systems (GNSS) to determine the user's geographic coordinates. It may also display the user's position on a map and offer routing directions (as in turn-by-turn navigation).

There are four global navigation satellite systems (GNSS): the United States' Global Positioning System (GPS), the European Union's Galileo, Russia's GLONASS, and China's BeiDou Navigation Satellite System. These systems are often used together to improve positioning accuracy and availability. In addition, regional systems such as India's NavIC and Japan's Quasi-Zenith Satellite System (QZSS), augment the accuracy of a number of GNSS over their respective regions.

A satellite navigation device can retrieve location and time information from one or more GNSS systems in all weather conditions, anywhere on or near the Earth's surface. Satnav reception requires an unobstructed line of sight to four or more GNSS satellites, and is subject to poor satellite signal conditions. Today, most standalone satnav receivers are used in automobiles. The satnav capability of smartphones may use assisted GNSS (A-GNSS) technology, which can use the base station or cell towers to provide a faster Time to First Fix (TTFF), especially when satellite signals are poor or unavailable.

History

Further information: Global Positioning System § History

The modern satellite navigation device grew out of the Cold War. The United States and Russia first developed these systems for their militaries. Later, other countries created their own systems for everyone to use.

In 1960, the US Navy started using a satellite system to help ships navigate. Over the years, this technology improved. In 1983, after an airplane accident caused by navigation mistakes, President Ronald Reagan allowed people to use the system too, though with less accuracy at first. The first commercial GPS device, the Magellan NAV 1000, was shown in 1989. Soon after, cars began including navigation systems. By 2000, the full system was open for everyone to use.

As these systems became popular, they got cheaper and more common. Many companies made them, and today, most smartphones have GPS built-in. Besides the US GPS, other countries now have their own systems, like Russia's GLONASS, the European Union's Galileo, and China's BeiDou Navigation Satellite System.

Technical design

GNSS devices have different abilities depending on how well they can pick up weak signals. Some special devices can find signals very quickly, which helps them figure out your location fast when you're outside. Even when signals are weak, like inside a building, these devices can still work by using extra power to find very faint signals.

The signals from GPS satellites are already very weak when they reach Earth. They become even weaker by the time they reach a device on the ground. Some devices are made to pick up these very weak signals, which lets them work even inside buildings, though they might not work everywhere. These special devices can sometimes see through walls or thick materials to find your location.

Types

Consumer GNSS navigation devices come in several forms:

• Dedicated GNSS navigation devices: These are special tools made just for finding your way. Some are small and easy to carry, good for hiking or biking. Others are made to use in cars and can show maps and give directions.
• Modules that connect to computers: These devices need to be linked to a computer to work. They can record trips and are useful for activities like hiking and making maps.
• Converged devices: Many modern devices, like phones and cameras, have GNSS as one of their features. These can also show maps and help with finding places.

Almost all smartphones today have GNSS, which lets them show maps and help with navigation. This is because people wanted this feature, and it helps services like emergency calls find where someone is. There are many apps for this, such as Google Maps Navigation, Apple Maps, and Waze.

Dedicated devices can be used while moving. Hand-held ones have batteries that last for hours and are good for activities far from power outlets. They are built to be strong and some can even work in water. Some devices for cars have touch screens and can store maps on memory cards. Many can also play music, show pictures, and videos.

Modern devices often show maps and can give step-by-step directions, sometimes talking to you. Companies that make these devices include Navman products, TomTom products, Garmin products, Mio products, Navigon products, Magellan Navigation consumer products, Satmap Systems Ltd, and TeleType products.

Other GNSS devices need to be connected to a computer, like a home computer, laptop, or smartphone. They can connect using different methods, such as USB or Bluetooth. These devices usually need the user to install special software to make them work. Some come with software already, and others are very affordable. Some people even make their own devices and share the plans online.

Applications

Vehicle navigation

An automotive navigation system uses satellites to find your location. It can show you maps, give you directions step by step, and even help self-driving cars. It can also show traffic jams and suggest better routes, as well as point out nearby places like restaurants or gas stations.

Aviation

Aviators use satellite navigation to fly safer and more efficiently. This helps pilots fly without needing help from the ground and can guide them to airports that don’t have special equipment. Some GPS units help pilots see better in poor weather. Many airlines now require pilots to use GPS. These devices give information to computers that control the plane, show courses to pilots, and keep track of the flight.

Military

The military uses satellite navigation devices for soldiers, vehicles, ships, planes, and missiles. Before May 2000, only the military could use the most accurate GPS signals. Now, everyday devices can also get very precise location information using a method called Differential GPS, which can be as accurate as a few centimeters.

Risks

GPS maps and directions can sometimes be wrong. This has caused people to get lost or end up in unexpected places, like private driveways that aren’t actually streets.

There are also privacy concerns with satellite navigation devices. When using these devices on phones or other gadgets, they might share your location with apps and advertisers. This means companies could track where you go and what you do. Some employers also use these tools to follow their workers, even when they’re not working. This can feel like an invasion of privacy.