GPS in a smartphone: what is it and how does it work? What is GPS and A-GPS? What is better to use

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 satellite signal allows you to accurately determine the coordinates of objects on the ground, as well as the speed of their movement. The military was the first to adopt the GPS system: 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 free navigation system high precision. There is no subscription to it and cannot be, 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 some minor drawbacks: they only work outdoors, and bad weather can cause problems with receiving a signal from the satellite, but these shortcomings have been solved with the help of 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 are suitable for pedestrians - it’s easy to navigate and the data is accurate, so you won’t get lost even in an impassable thicket.

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), 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. 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 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, 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, operating on the basis of 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 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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This is a computer and a receiver housed in a common housing. The receiver receives signals from satellites in orbit, and the computer, in turn, deciphers these signals and indicates the location of the receiver. In 1977, GPS was launched. It was launched by the developers of the program itself - the Americans. The GPS system was used until 1983 only by the military, and only after that it became available for use by ordinary people.

Many owners of GPS navigators have noticed that in their locations large quantity tall structures and buildings the device searches for satellites quite for a long time. The solution to this problem was the A-GPS system.

Let's look at what A-GPS is and when it is needed.

Considering that this system is quite young (its debut was in 2001), the question of what A-GPS is is currently relevant. It, like GPS, was developed in the USA. A-GPS is a system that speeds up the operation of a GPS receiver in determining coordinates. This system uses the signal emanating from cellular towers; accordingly, the more visible the device of these towers is, the higher the accuracy of determining the distance. At every starting search A-GPS satellites provides the navigator with the location of the closest satellites through special servers. Finding out what A-GPS is , It becomes clear that with its help the work of the GPS navigator will become much more efficient. After all, thanks working together two devices, location determination is significantly faster.

Having decided what A-GPS and a GPS navigator are, it’s worth paying attention to the GPS tracker. This device is designed to monitor via satellite the movement of an object on which this small electronic device. A GPS tracker is a kind of “bug” that can be easily hidden, for example, in the interior of a car, and thus track all further movements of this object.

Basically, a GPS tracker includes 2 devices: a GPS receiver and a GSM modem. With help, he is able to determine the coordinates of movement and speed, and then transmit this data to the observer via a GPRS channel (via cellular communication).

Having learned everything about navigators from our article, you can safely purchase this device, because in a modern city, especially if it is simply impossible to do without this technology.

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.

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. First worker 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. The average service life of a satellite is 10 years. After this period, a new one 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 drawback. 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 a global positioning system. To put it quite simply, then this system represents 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 return to GPS technology, it is not only used 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 is needed on the speed of the vehicle and the estimated time of arrival at the 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 short time The so-called cold start, when the navigation system has not been used for a long time, 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 includes information about different modules. If in some we are talking about a GPS module, then in others we are talking 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 a remote server, from which the information necessary for the GPS receiver is received. 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 that quick identification 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. Besides, A-GPS application 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.