Global Positioning System (GPS) – GPS- NAVSTAR properly (Global Positioning System – NAVigation Signal Timing And Ranging ) – one of the satellite navigation systems , created by the U.S. Department of Defense , including its coverage over the entire globe. The system consists of three segments : the space segment – 31 satellites orbiting the Earth at an average orbit , ground segment – control and monitoring stations on the ground and user segment – signal receivers . The purpose of the system is to provide the user with information about its location and to facilitate navigation in the area.

The measure consists in measuring the time of arrival of a radio signal from the satellites to the receiver. Knowing the speed of electromagnetic wave , and knowing the exact time of sending the signal , you can calculate the distance of the receiver from the satellites. The GPS signal contains the information about the layout of the satellites in the sky (the almanac ), and information about their theoretical way , and deviations from it (so-called ephemera ) . The GPS receiver in the first phase update this information in its memory, and later used to determine its distance from each satellite , for which the receiver is in range. By performing linear spatial Resection microprocessor receiver can calculate the geographical position ( longitude, latitude and altitude ellipsoidal ) and then give it to the selected reference system – the default is WGS 84 , as well as the current GPS time with very high accuracy .

GPS is operated and managed by the U.S. Department of Defense . Use its services can in principle everyone – just have a suitable GPS receiver. Such receivers are manufactured by independent commercial companies . The GPS system is free and so is expected to remain in accordance with the policy of the United States.

An essential element of the system is to identify signals from different satellites by the GPS receiver . This is done through the use of pseudo-random noise (PRN – Pseudo -Random – Noise ) . PRN in its main function is to digitally enhancing the transmitted signal (so we do not need huge plates for the reception of satellite signals ) and allows the Department of Defense to control access to the GPS system. As a result, the military can use the GPS signal to transmit encrypted messages.

GPS on your phone

GPS in the phone is undoubtedly a very useful function . Probably many of you , being in a new place , studied the area using just the technology. As everyone knows , using GPS can determine our location on a map , making it easy orientation in the field. However, beyond this basic GPS function often entails other additional .

What does the GPS on your phone?

Such interesting additions is undoubtedly geotagging . Roughly Geotagging is a feature that allows data connection made ​​geographical coordinates of photography. With this solution , each picture taken in conjunction with the geotag is assigned to the exact location on the map. Who of you has never happened to forget where he made ​​that scene ?

At the pre must remember , however, a few simple , but important concepts that will facilitate the use of GPS :

 Fix – it is nothing like our first download the correct position.

 Assisted GPS ( AGPS or A -GPS) – type GPS system , wherein in order to shorten the time required to determine the position of the first server uses the mobile network operator . This service , of course, must be available from the operator , otherwise the GPS will work , but the longer it takes the first ” connection to the satellites .” Also keep in mind that A -GPS in most cases will be a paid service because of the cost to the transmission of data by the operators.

 Cold Start – is the process of determining the position of the first ( if your phone does not connect to the satellites in the last 4 hours) , which is in good weather conditions up to 40 seconds.

 Warm Start – this process takes from 20 minutes to 4 hours after the last use of the navigation . It takes – depending on the model and the receiver – from 7 to 35 s

Hot Start – It takes time no later than 20 minutes after the last run of navigation. The 20 minutes is the time in which your phone is synchronized with GPS . This process takes time from 1 to 3 seconds .

 GPS In older phones

Most new phones , especially smartphones , have a built-in GPS . But what to do when we have an older cell phone and do not want to change it , and the navigation is vital to us ? To do this you need to buy a GPS module that connects to your phone via Bluetooth . On popular auction sites or online stores for such a device will have to pay about 100$.

This solution is now becoming less popular , but used so far. The big advantage of an external GPS module is very often better quality receiver.