What is the difference between GPS and A-GPS? The most important thing about GPS navigation: what is GPS and why is it needed?

The Global Positioning System appeared in the 50s thanks to the launch of the satellite. When the first Soviet satellite went into orbit, the Americans noticed: as it moved away, it evenly changed the frequency of the signal. Scientists analyzed the data and realized that the satellite signal makes it possible to accurately determine the coordinates of objects on the earth, as well as the speed of their movement. First GPS system The military adopted it: the Ministry of Defense launched satellite navigation for its own purposes, but after a few years it became available to civilians.

There are currently 24 satellites in low-Earth orbit that transmit binding signals. The number of satellites changes periodically, but always remains sufficient to maintain the smooth operation of the Global Positioning System. In case of force majeure, spare satellites are provided, and every decade new, modernized spacecraft go into orbit, because nothing should disrupt the operation of GPS.

The satellites orbit in six orbits, forming an interconnected network. It is operated by dedicated GPS stations that are located in the tropics but linked to a focal point in the United States. Thanks to this network, you can find out the exact coordinates of a person, car or aircraft at the speed of signal transmission from satellites, that is, almost instantly, and the accuracy of the readings does not depend on weather conditions and time of day. At the same time, the use of the Global Positioning System itself is free, and the only thing you need to use this navigation system is a navigator or other device that supports the GPS function.

How GPS works

The technology is based on the simple navigation principle of marker objects, which was used long before the advent of GPS. A marker object is a landmark whose coordinates are precisely known. To determine the coordinates of an object, you also need to know the distance from it to the marker object, then you can draw lines on the map towards the markers from the possible location: the point of intersection of these lines will be the coordinates.

Satellites in low-Earth orbit play the role of marker objects in GPS. They rotate quickly, but their location is constantly tracked, and each navigator has a receiver tuned to the desired frequency. Satellites send signals that encode a large amount of information, including exact time. Precise time data is one of the most important for determining geographical coordinates: Based on the difference between the output and reception of the radio signal, the satellites calculate the distance between themselves and the navigator.

How GPS works in smartphones

Navigators are one of the most popular products on the gadget market; they are surpassed in popularity only by smartphones. But manufacturers also integrate GPS chips into smartphones so that the device can perform the functions of a navigator. However, a trap may lie in wait for the user here, because in the pursuit of profit, manufacturers allow intentional or accidental inaccuracies in the description of their product, allowing buyers to confuse GPS technology and AGPS.

Jeepies is a free high-precision navigation system. There is no subscription to it and there cannot be one, because the Americans allow the use of their satellites for navigation free of charge. Smartphone owners, if they pay, pay only for applications or cards. GPS receivers have small disadvantages: they only work outdoors, and due to bad weather there may be problems with receiving a signal from the satellite, but these disadvantages were solved using A-GPS technology (not to be confused with AGPS). The bottom line is that the signal from the receiver is redirected to a server that contains all the information about the position of the satellites, so there are no difficulties in receiving the signal. A-GPS is used by all modern car navigators.

But there is also AGPS cellular navigation - it only works in the coverage area cellular network and determines the location with an accuracy of up to 500 m. It is less accurate in comparison with GPS, it gives a general idea of ​​​​the place where you are, but it offers a satellite map of the surrounding area. It is important that the service is activated mobile internet, and there was money left in the account. They work with the AGPS service Google Maps. Often, cellular navigation capabilities are sufficient, but it still should not be confused with accurate and free system GPS.

Types of GPS devices

The simplest navigation device is an external receiver. It communicates with satellites and receives signals from them, but in order for you to use the information, the receiver needs to be connected to another device - for example, a smartphone or laptop; fortunately, it is compatible with all popular gadgets and programs. As a last resort, you will need a card. GPS receivers are used by hiking tourists: the device is inexpensive, and to decipher the information it receives, you can even use a regular tourist map of the area. You just need to have a navigation mesh overlaid on it.

But the most popular GPS device today is a car navigator. It is much more complex and functional than the receiver: the navigator is more like a smaller version of a computer. All necessary software already installed by the manufacturer, the operating system is closed. They add a lot to navigation additional functions, including Internet access.

A separate class of devices are smartphones with built-in GPS receivers. Do not confuse them with models that use cellular navigation! The system does not work as smoothly on smartphones as on stand-alone devices. Not all models allow you to install full-fledged navigation software, and if you use online solutions, the function will become unavailable when the Internet is turned off, and then one of the advantages of the technology will disappear: constant access. However, smartphones with satellite navigation suitable for pedestrians - it’s easy to navigate and the data is accurate, so you won’t get lost even in impassable thickets.

Increasingly, smartphones are used by their owners as navigators, since it is very convenient to always have a compact device on hand that allows you to determine your location or build a route to the desired object.

It communicates with satellites in orbit, receiving signals from them, and shows its coordinates on the map. Sometimes, due to various circumstances, detecting available satellites can be difficult and takes long time. This occurs in buildings, tunnels, and also near sources electromagnetic radiation. Even outdoors in large cities with dense buildings may experience interruptions in the satellite signal.

To correct this situation, the A-GPS function is used, which is found in most modern smartphones.

A-GPS technology

A-GPS is a technology that provides the GPS module additional information about the most accessible satellites and their signal strength. When you turn on navigation, the smartphone almost instantly determines its location on the map, and searching for satellites is possible even in enclosed spaces, and interfloor ceilings are not a hindrance.

Successful start A-GPS occurred in the USA in the fall of 2001 as part of communication networks national rescue service (911).

How does A-GPS work?

For up-to-date information this technology uses alternative communication channels. In the case of our smartphones, this is the Internet provided by a cellular operator or via Wi-Fi.

A-GPS communicates with its servers, transmitting location information, which is determined by the operator’s base stations (towers). In response, these servers receive fresh messages about active satellites in the area. Using them, the smartphone’s geolocation module quickly establishes a connection with necessary companions, without wasting time searching for everyone. The more base stations around the smartphone, or the closer the user is to a cell tower, the more accurately the location of the smartphone is recorded, which means more correct information about available satellites.

Pros and cons of A-GPS

As we can see, the benefits of having A-GPS are undeniable. This and quick installation communication with satellites, and battery saving, since during a “cold” start and searching for signals GPS module consumes battery power intensively. At the same time, communication with servers consumes very little Internet traffic - up to 10 kilobytes per session. It is important that A-GPS does not require user participation, and data updates occur automatically as needed.

But this function also has disadvantages, albeit minor ones. It will not provide fast communication with satellites in areas with a shortage of towers mobile operators or their absence. Therefore, far from civilization, A-GPS is useless.

Despite modest internet consumption, regular frequent A-GPS updates and synchronization will result in increased traffic. And when you are in roaming, especially international, communication costs can increase significantly.

How to enable or disable A-GPS?

When activating the “Geodata” function (GPS navigation, geolocation), the smartphone prompts you to select a determination method. The user can prioritize battery conservation or geolocation accuracy. Typically, the following methods are available (menu item names may vary depending on the Android version and phone manufacturer):

• According to all sources (high accuracy). Location is determined using GPS, Wi-Fi and Internet traffic mobile networks. A-GPS technology is active.
• By network coordinates (conserving battery charge). The location is detected when Wi-Fi assistance and and mobile networks. GPS protocol is disabled, A-GPS is active.
• By GPS satellites(device only). Determining location solely by satellites without using additional communication channels. A-GPS technology is disabled.

A-GPS technology is necessary for normal navigation using a smartphone - it can be used regularly.

2 years ago

Navigation today is a simple, necessary and incredibly popular service. Not only are navigators almost the most hot commodity in the mobile market (only the ubiquitous phones are ahead of them), many smartphones over the past couple of years have acquired their own GPS and A-GPS chips - and users are so accustomed to this that a “smartphone without navigation” now makes them at least , astonishment. All this, of course, is very pleasing (progress! civilization!), but there is only one problem: manufacturers are trying so hard to sell their goods that they often wishful thinking, luring buyers not with the specifications of their goods, but with big words on the boxes. We will tell you what these words mean and what navigation actually is like in this article.

Technology: how does it work?

Today, there are, in fact, only two technologies that allow mobile technology users not to get lost in the concrete jungle: satellite and cellular navigation. The first is GPS itself, a global satellite positioning system invented by American scientists for the American military, and then presented to the rest of the world for Thanksgiving. The second is AGPS (not to be confused with A-GPS), a cellular technology that allows you to determine your approximate location (with an accuracy of 500 meters) if you are in a cellular network coverage area.

GPS is good, first of all, because it is accurate (it determines your position to within five meters) and absolutely free (good Americans allow everyone to use their satellites). Of course, you will have to pay for specific navigation programs and maps - but this payment will be a one-time fee, and no subscription to GPS services exists in nature. The bad thing about GPS is that it only works outdoors, and mainly in clear weather - if the sky is cloudy, it’s quite difficult to find the number of satellites needed to work. In order to fight clouds, it was invented special technology A-GPS (Assisted GPS): with this technology, instead of sending signals into the skies, the navigator simply connected to a certain server, where it downloaded information about the location of satellites, and, using these coordinates, found them much faster. Today A-GPS is an indispensable companion to any GPS receiver car navigator. The most popular cards that work with GPS service: iGo, Autosputnik, Navitel, Be-On-Road.

The cellular system AGPS (Alternative Global Position System) gives, of course, a much less accurate determination of the position of an object on the map, but it does not depend at all on the weather and the depth of the building. The main thing is that your smartphone can catch the network, your number is connected GPRS service, and there was still money left in your account. The operating principle of AGPS is similar to that of satellite system navigation: the smartphone receives signals from several (at least three) base stations and, based on the signal strength of each of them and taking into account their location, calculates your coordinates. Cheap and cheerful: you, of course, won’t be able to get anywhere with AGPS, but you definitely won’t get lost on the map. The most popular maps that work with the AGPS service: Google Maps, Yandex.Maps.

Devices: what happens?

The simplest GPS navigation device that exists in nature is an external GPS receiver. By itself, it only communicates with satellites, and, in fact, does not provide any navigation. But you can connect it to almost any device - laptop, pocket computer, telephone or smartphone - and then, if you have the right software, you will be able to navigate in space and get directions to your destination. Receivers are especially useful for tourists who prefer narrow mountain or forest paths to well-trodden roads: receivers, unlike most other devices, are not tied to a map, and if you really want to, they can even guide you along scanned graph paper with a navigation grid superimposed on it. If, of course, you find one for the region you need.

The most popular navigation device today is car GPS navigator. This is, in essence, small computer With touch screen, running on a closed operating system. The navigator already has a navigation program installed by the manufacturer, which usually cannot be changed without violating licenses. In addition to navigation itself, car navigators can often do many other things: play music, show movies, work with e-books and images, and even connect to the Internet.

IN lately A new class of devices has appeared on the market - smartphones with a built-in GPS receiver. On the one hand, these devices are extremely convenient: they can make calls, tell you the way, and do a lot of other things. On the other hand, the software component of such devices is still very weak: mainly in quality navigation programs“online solutions” like Nokia Maps or Google Maps are used, which require a constant Internet connection to work with (although some smartphones can also be equipped with real navigation software). Yes, and such smartphones are more suitable for pedestrian than for car navigation - their screen is small, the map is difficult to see, and with maps of our vast homeland, everything is bad, to put it mildly. You can only travel around the city.

The latest type of navigation devices are smartphones with cellular navigation (AGPS). They do not have a built-in GPS chip. They are suitable only for those who do not want to carry a paper map with them - neither guidance on the route, nor even precise definition They don't give you your location. But they are great for helping you navigate space during a long trip or find some particularly inconspicuous alley that none of the passers-by you interviewed had heard of.

Unfortunately, there is no ideal map in nature (if only because everyone has their own idea of ​​the ideal), so first you have to understand why you need a navigator in principle and what you will do with it: one type is suitable for hiking trips devices and maps, for car navigation – another, for pedestrian navigation – a third. In addition, you need to pay attention to the cartographic database itself: the nicest-looking program may suddenly not have a map of your city, and the most “urban” of the maps will show you blank spots right behind the ring road. In general, no matter how you look at it, you still have to devote some time to the selection process. You can read about how to choose a map for your navigator in the article “What types of navigation maps are there?”

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Smartphones have long ceased to be simple dialers. They opened up a lot of new opportunities for their owners.

In the first place is full-fledged high speed access Internet and communication social networks and messengers. But GPS positioning is no less in demand, which we will now discuss in detail.

What is GPS?

GPS is a navigation system that determines the location of a smartphone, builds routes and allows you to find the desired object on the map.

Almost every modern gadget built-in GPS module. This is an antenna tuned to the GPS geolocation satellite signal. It was originally developed in the USA for military purposes, but later its signal became available to everyone. The gadget's GPS module is a receiving antenna with an amplifier, but it cannot transmit a signal. Receiving a signal from satellites, the smartphone determines the coordinates of its location.

Almost every modern person has used GPS navigation on a smartphone or tablet at least once. The need for it can arise at any time among people of different professions and different occupations. It is necessary for drivers, couriers, hunters, fishermen and even ordinary pedestrians who find themselves in an unfamiliar city. Thanks to such navigation, you can determine your location, find the desired object on the map, build a route, and, if you have access to the Internet, avoid traffic jams.

Offline maps for GPS

Google has developed for its operating system Android special geolocation application - Google Maps. It quickly finds satellites, develops routes to objects and offers alternatives. Unfortunately, in the absence of cellular coverage Google network Maps does not work, since geographic maps are downloaded via the Internet.

For offline navigation the best way out will download applications that support offline maps, for example, Maps.me, Navitel and 2GIS. You can also install the Maps: Transportation and Navigation app for Google Maps.

In this case, you won’t have to spend Internet traffic to download maps - they will always be on your device, regardless of location. This is especially true when you are abroad, since the cost of roaming for Internet access is very high.

How to enable GPS on Android?

Activating the GPS module in the operating room Android system possible in two ways:

• Top curtain. Swipe down on the display and in the menu that opens, click the “Location”, “Geolocation” or “Geodata” button (depending on the Android version).
• IN Android settings Find the item similar items and move the checkbox to the “Enabled” position.

During active work navigation system Smartphone battery power begins to be consumed quite actively, so it is worth taking care of additional power sources. For example, while driving you need to use car charging, and when traveling by bicycle or on foot - .

It is also worth remembering that confident reception satellite signal is possible in open areas, so when you are in a room or tunnel, geolocation becomes impossible. Cloudy weather also has an effect - because of the clouds, the device takes longer to search for satellites and determines its coordinates less accurately.

Not long ago, GPS was the only geolocation system, so in the early Android versions Only she was mentioned, and the service activation button was called that. Since 2010, the Russian one has been fully operational, and since 2012 -.