What does a gps mean? What is GPS and A-GPS? What A-GPS technology doesn't do

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 Internet access and communication in 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 signal of the system satellites GPS geolocation. 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 types of 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 coverage area cellular network Google Maps doesn't work because geographic Maps here they are downloaded via the Internet.

For offline navigation, the best way is to download applications that support offline maps, such as 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 the display and in the menu that opens, click the “Location”, “Geolocation” or “Geodata” button (depending on Android versions).
• IN Android settings Find the item similar items and move the checkbox to the “Enabled” position.

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

It's 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 earlier versions Android was the only one mentioned, and the service activation button was called that. Since 2010, the Russian one has been fully operational, and since 2012 -.

Navigation today is a simple, necessary and incredibly popular service. Not only are navigators almost the most hot commodity on mobile market(only the ubiquitous phones are ahead of them), and over the past couple of years, many smartphones have acquired their own GPS and A-GPS chips - and users are so accustomed to this that a “smartphone without navigation” now causes them, at least, surprise. 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 essentially only two technologies that allow users mobile technology Don't get lost in the concrete jungle: satellite and cellular navigation. The first is GPS itself, global satellite system positioning, 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), technology cellular communications, which 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. It's too bad GPS themes that it only works outdoors, and mainly in clear weather - if the sky is cloudy, it is quite difficult to find the number of satellites required for operation. In order to deal with clouds, a special A-GPS (Assisted GPS) technology was invented: with this technology, instead of sending signals to 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 maps that work with the GPS service: iGo, Avtosputnik, 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 principle of operation of AGPS is similar to the principle of operation of a satellite navigation system: 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, PDA, phone 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. It's essentially a 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 appeared on the market new class devices – 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, to work with which you need permanent connection to the Internet (although some smartphones can also have real navigation software). And such smartphones are more suitable for pedestrians than for car navigation– their screen is small, the map is hard to see, and with the 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 - they do not provide route guidance or even an accurate determination of your location. But they do a great job of helping you orient yourself in space during 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 just beyond 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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GPS technology is used not only by car enthusiasts and taxi drivers. It is also popular among outdoor enthusiasts, fishermen and just people driving active image life and constantly walking/driving back and forth. If someone needs to know where he is, where the location he needs is located, how fast he is moving and how soon he will reach his goal, GPS will come to the rescue.

The reason for the widespread popularity of this technology lies in the following:

• coverage area covers the entire globe;
• the technology is used not only in expensive secure GPS trackers, but also in relatively cheap GPS navigators for cars and even in smartphones;
• There is no need to pay for using GPS.

Read more about what GPS is

GPS is an abbreviation for the English concept Global Positioning System, which is translated into Russian as “global positioning system”. This project was conceived and implemented by the US military exclusively for military purposes, but later became widely used for civilian needs.

The basis of the GPS system is 24 NAVSTAR navigation satellites, which make up single network and located in Earth's orbit in such a way that from any point globe At least 4 satellites could be accessed.

The performance of the global positioning system is monitored from Earth by observation stations located in the Hawaiian Islands, in the city of Colorado Springs (Colorado), in Kwajalein Atoll and on the islands of Ascension and Diego Garcia. All information collected by these stations is recorded and then transmitted to the command post, which is located at Shriver Air Force Base (Colorado). Here the navigation information and satellite orbits are adjusted.

The GPS tracker coordinates are calculated according to the following principle. A radio signal passes from each navigation satellite to a receiver located in their access area. The delay of this signal is measured, and from these measurements the distance to each satellite is calculated. The location of the receiver is calculated based on measuring the distance from it to all available satellites (in geodesy this method is called triangulation), the coordinates of which are known and contained in the signals they transmit.

The GPS receiver is capable of not only determining its location, but also calculating the speed of movement, the time it takes to reach the designated place, and showing the direction. But this already applies not so much to the capabilities of the GPS system itself, but to the navigator software.

About the history of GPS and navigation satellites

The idea of ​​creating a system satellite navigation Americans caught fire back in the 1950s, when the first artificial satellite Earth. In 1973, the DNSS program was launched, which was later renamed Navstar-GPS, and then simply GPS. The first satellite (test) was launched into orbit in 1974.

After the first Soviet navigation satellite GLONASS (Global Navigation Satellite System) was launched into orbit in 1982, the US Congress allocated funds to the US military to speed up the work. The first working GPS satellite was launched in February 1978, and the system began to operate at full capacity at the end of 1993, when all 24 satellites took their places in Earth orbit.

Each navigation satellite weighs about 900-1000 kg, and in length with open solar panels reaches 5 meters. Average term satellite service life - 10 years. After this period, a new satellite is launched to replace the exhausted satellite.

About GPS receivers

The speed of calculating coordinates when the receiver is turned on, its sensitivity and positioning accuracy are determined by the chipset with which it is equipped. Chipsets for GPS devices are made by several manufacturers, but the most common is SiRFstarIII from SiRf Technology.

Receivers with the SiRfstarIII chipset have a short cold start time (a few seconds) and can simultaneously receive signals from 20 satellites. They are very sensitive and allow you to determine coordinates with high accuracy.

What is the difference between GPS and A-GPS

The list of characteristics of some smartphones indicates the presence of a GPS module, others - A-GPS. How are these modules different?

During a cold start (when the navigation system has not been used for a long time), a device with a conventional GPS receiver can search for satellites for a long time - the waiting time sometimes reaches 10 minutes or more. This is because the GPS receiver searches for satellites without knowing their location.

At using A-GPS the device immediately receives part of the necessary information using the GPRS/3G network (traffic no more than 10 KB). Thus, A-GPS is a software add-on over the GPS receiver, which significantly reduces the time it takes to search for satellites during a cold start. In addition, this add-on allows you to increase location accuracy in areas with weak satellite signals.

However, A-GPS has one small disadvantage. Unlike GPS, which is completely free to use, A-GPS must be paid according to the tariff set by your provider, since it consumes Internet traffic (however small).

Let's start with the fact that GPS or Global Positioning System is global system positioning. To put it quite simply, then this system represents a virtual card, with which the user can determine his location. It is worth noting that the above system has nothing to do with GPRS (General Packet Radio Service), since the latter is a so-called GSM add-on for packet data transmission for accessing the mobile Internet.

If we still return to GPS technology, then it is used not only by motorists, as many people think. The scope of use of the GPS system is much wider. For example, it is very popular among travelers, hunters, fishermen and other people who prefer an active pastime and who from time to time need information about their own location or the location of a particular location. In addition, if information on movement speed is needed vehicle and estimated time of arrival at your destination - GPS can become an indispensable tool.

Note that GPS receivers differ in the speed with which they can calculate coordinates from the moment they are turned on, as well as in the sensitivity and accuracy of positioning. All these parameters depend on the chipset that the GPS receiver is equipped with. There are chipsets for GPS devices from a number of manufacturers on the market, however, the most popular are the SiRfstarIII chipsets, produced by SiRf Technology. Receivers equipped with the SiRfstarIII chipset demonstrate a short so-called cold start time, when the navigation system has not been used for a long time, it lasts a couple of seconds. In addition, these chipsets make it possible to receive signals from 20 satellites at once. Moreover, GPS receivers with SiRfstarIII chipsets are considered the most sensitive and have highly accurate position determination capabilities.

What is the difference between GPS and A-GPS?

To begin with, it is worth mentioning that in technical specifications smartphones contains information about different modules. If in some we're talking about about the GPS module, then in others about A-GPS. So what is their difference? If the device is equipped with a regular GPS receiver, then during a cold start (read what this is - read above), the search may take longer because the navigator cannot quickly find the satellite, and this can last for more than one minute. The reason for the long search for a satellite by a GPS navigator is simple - the lack of information about the actual location of the satellite.

If your device uses A-GPS technology, then necessary information V operational mode arrives using a GPRS, 3G or LTE (4G) network (traffic does not exceed 12 KB). At its core, A-GPS is a software add-on for a GPS receiver, with the help of which the satellite search time during a cold start can be significantly reduced. As already noted, acceleration is achieved mainly through alternative communication channels. By and large, for A-GPS technology to function, it requires a communication channel with remote server, from which the information necessary for the GPS receiver comes. If we return to mobile devices, then in their case it is an Internet connection via cellular or Wi-Fi.

Note that the A-GPS add-on has both advantages and disadvantages. If we start with the advantages, it is worth noting the very fast determination of coordinates immediately after switching on. In addition, the technology enhances reception sensitivity weak signal in so-called dead zones - tunnels, indoors, in valleys, etc. However, a significant disadvantage of A-GPS is the inability to work where there is no cellular network coverage. In addition, the use of A-GPS cannot be absolutely free, like, for example, GPS. This is due to the consumption of Internet traffic by the A-GPS add-on, which must be paid depending on the tariffs of a particular Internet provider.

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 there are around the smartphone, or the closer the user is to cell tower, the more accurately the location of the smartphone is recorded, which means the more accurate the 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 is updated automatically as needed.

But this function also has disadvantages, albeit minor ones. She won't provide fast connection 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 updates and A-GPS 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 determination occurs when GPS assistance, Wi-Fi and Internet traffic mobile networks. A-GPS technology 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 channels communications. A-GPS technology is disabled.

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