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How does a GPS tracking system work?

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velappan
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re: How does a GPS tracking system work?
velappan   10/29/2010 5:37:05 AM
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i have knowledge in GPS and how to comments used in pic micro controller... plz help me..

Jagdish Bisawa
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Jagdish Bisawa   10/29/2010 7:20:38 AM
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Velappan, With an incomplete, improperly famed question, nobody will be able to help you. Please frame your questions in a correct manner & maintain the content-sanctity of the site.

Panch
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Panch   10/29/2010 12:03:54 PM
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Can you comment on how GPS and a map (e.g. Google map) can interact? If I give the destination location, how is it able to map the best possible route and track if I am going on the right track? Another related question I have is that for the active system, does it mean that the receiver sends a feedback signal back to the satellites? If so, how does it work? If not, what is the path taken for the reverse data tx?

Larry M
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Larry M   10/29/2010 1:47:51 PM
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Panch, This is a classical Computer Science problem. All roads are represented as a giant graph with intersections as nodes and distances associated with each branch (road) connecting two nodes. Using Depth First Search or Breadth First Search, all paths are tested, abandoning each path as soon as its accumulated length exceeds any previously generated path. If the user specifies, preference can be given to branches designated as e.g., Interstate highways. If the device senses that you have deviated from the given path, it simply generates a new route from the current location to the given destination.

Jagdish Bisawa
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re: How does a GPS tracking system work?
Jagdish Bisawa   10/29/2010 1:02:56 PM
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The GPS Map integration is not a simple affair & is probably out of the scope of this article. Normally, the Map software is integrated with another software that is reading the GPS co-ordinates, using the API of the Map software. How it can find the optimum path depends on the path-tracking algorithm that is used. You have misunderstood the definition of Active GPS. Active GPS does not reply back to the satellite ( it is still a one-way communication). However, Active GPS enables the transmission of the position information, using available network to a (usually) central server. The central server thus enables monitoring of the GPS co-ordinates in real-time, thereby leading to application like Vehicle Tracking System or human-tracking.This is in contrast to the Passive GPS systems that the author is talking about. Passive GPS sytems store the data in their memory devices, to be read-out by the user or to be transmitted at fixed transmission points along the journey

an800127
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an800127   1/8/2013 2:58:02 AM
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Hi thanks for the detail insight. Although i have another confusion on its usage. As being a caregiver after purchasing any ACTIVE micro gps tracker . what all i need to do so that i can see track my loved for her safety. bascically what will the receiver/medium for this.

BillsBlots
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BillsBlots   10/29/2010 2:15:25 PM
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Panch, our GPS system (more appropriately called "Automatic Vehicle Location", or AVL) can turn on a feature enabling the export of the GPS information in a .kml file to Google maps at specified intervals, typically every 1 to 5 minutes. The vehicle icons, speed, direction and identification information of our fleet are overlayed on Google satellite maps, pretty darn cool. All AVL systems overlay that same basic vehicle information on a map system installed on the user's computer, or more typically, the data is collected at a service provider web site to which managers are given login permission and can view location depicted on the host service's map.

yalanand
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re: How does a GPS tracking system work?
yalanand   10/31/2010 1:48:28 PM
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Thanks for the article. But why do we need 3 satellites ? Who owns these satellites ? And how many satellites are there which are used for GPS currently ?

David Ashton
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re: How does a GPS tracking system work?
David Ashton   10/31/2010 10:30:11 PM
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Most of the answers to your questions are within the article: "The Global Positioning System is mainly funded and controlled by the U.S Department of Defense (DOD)" "The Space Segment of the Global Positioning System consists of 27 Earth-orbiting GPS satellites. There are 24 operational and 3 extra (in case one fails) satellites.." As we are working in a 3-d environment, 3 satellites will give you a 2-dimensional location on the earth's surface, and 4 satellites will give you a 3-dimentional location (ie position plus height). I never was much good at 3-d trig but I can see how this works. Think of disks from each satellite (like saturn's rings) intersecting at your position on the earth's surface. 2 satellites will give you a line where you might be, 3 will give you a point and 4 will give you height as well.

przemek0
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przemek0   6/19/2013 6:20:44 PM
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It's in 3D so you don't get lines but rather circles from intersecting spheres. Each satellite signal carries the timing information. This allows you to calculate the distance to each satellite, i.e. you know that you are somewhere on a sphere whose radius is equal to that distance. If you decode distance to two of the satellites, you know that you are somewhere on a circle formed by intersection of the respective spheres centered at those two satellites. If you add another satellite, it will fix your position to an intersection of three circles, and you can eliminate some of the points because they will be too high or too low with respect to the earths's surface. Also, the inevitable inaccuracy of the solutions is worse for the vertical component, so it requires four or more satellite acquisitions, even though three should theoretically provide a full 3D solution.

phoenixdave
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phoenixdave   10/31/2010 8:25:16 PM
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@yalanand: I believe there are are currently a minimum of three satellites required for the current GPS systems in order to triangulate the coordinates of the target (the users).

David Ashton
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David Ashton   10/31/2010 10:34:43 PM
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Great article. Would it be too much to ask that we come up with a universal standard of how to transmit GPS location automatically from phones equipped with it whenever a 000 / 112 call is made? It would (a) help emergency services and (b) help trace nuisance callers. With the intelligence in phones these days it should not be difficult. The hard part is getting mankind to agree on a standard for it without too much bickering......

cbonilla
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cbonilla   11/1/2010 2:44:01 PM
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the more satellites your receiver can see the more accurate the positioning. Think about it, you are triangulating, therefore, the more perspectives you have the better the outcome.

Aleksandartomic
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Aleksandartomic   11/5/2010 12:50:27 PM
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There are many articles about how GPS works. Usually there are not targeting core of the explanation of the GPS system… Triangulation is simple to understand but never saw article to explain simple principle so I can say … Yes! I understand now… waoo! Just to mention triangulation term is not enough to explain GPS. But we can get sense that we understand something about GPS by using words triangulation. Triangulation, but where is simple explanation about tightly synchronization between satellites, delays between channels inside receiver. Something about signal sent from satellite, or how is signal coded, how GPS receiver which cost £40 is capable to receive so many channels to decode them to calculate accurate delays between channel and at same time to process data (which in turn produce delays). It must be some very creative ideas behind that. There are a fantastic and exciting ingenious solutions how all this is solved, really exciting and is not necessary to be complex explanation at all but core of the explanation of the GPS system has been always avoided to be explained on nice popular way to the wider public...

BillsBlots
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re: How does a GPS tracking system work?
BillsBlots   11/5/2010 1:54:58 PM
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Aleks, the timing and synchronization are a bit complicated for the scale of this well-scoped article, but the issues you raised have ingenious solutions. The fact that a typical family now may have 3,4, or 5 GPS enabled devices at an ever cheapening price is a testament to Economies of Scale and a free market economy. The GPS capability, formerly requiring a stand alone box for all the receiver circuitry, is now mass produced on a chip that may be embedded in most anything, and which includes a sophisticated satellite receiver and communications interfaces, requiring only connection to an antenna to receive the radio signals from the satellites. The laws of physics that determine radio energy path loss from satellite to ground have not changed, but are increasingly overcome by efficient circuits, more transmit power at the satellite, and phenomenally stable and sensitive receivers on earth, allowing us to "get away with" smaller and smaller antennas on earth to maintain the same radio path budget. It is remarkable both technically and to be so affordable, now considered mundane and to be an expected feature of everything from phones to automobiles, even for security of a mechanic's tool box which may be equipped with a GPS and cell phone that automatically dials for help and gives its location when it believes it is being stolen.

Ndukuru
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re: How does a GPS tracking system work?
Ndukuru   11/2/2012 2:09:01 PM
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Thanks for your article.I am currently looking for a means of tracking items that are about 13,000ft subsea and at pressures of 10,000psi max and 400degF max.How can GPS tracking be applied to such conditions?

babylon5
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re: How does a GPS tracking system work?
babylon5   5/8/2013 3:43:51 PM
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Ndukuru, In order to use the GPS system, the receiver mist be able to see the satellites. The signal from the satellite will not penetrate the water to any significant depth.

an800127
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re: How does a GPS tracking system work?
an800127   1/8/2013 3:00:13 AM
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Hi Thanks for the detail insight. Although I have another confusion on its usage. My question is as being a caregiver after purchasing any ACTIVE micro gps tracker . what all I need to do so that i can see/track my loved for her safety? bascically what all can be the receiver/medium for gps tracking Transmitter( web, mobile apps, any other device etc...).

MeirG
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re: How does a GPS tracking system work?
MeirG   5/9/2013 9:51:57 AM
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This article left a lot to be explained about the working of the GPS. I strongly advice the reader to ignore what he read here and refer to better explanations, e.g. from Wikipedia (http://en.wikipedia.org/wiki/Global_Positioning_System). A receiver uses the accurate position of at least FOUR (not three!) satellites and its DISTANCE to each to estimate FOUR values: earth longitude, earth latitude, elevation (or rather distance from the center of the earth) and time (yes, time, to a rather high precision!) The position and distances to a given satellite determines a sphere on which the receiver must be positioned. The intersection of three such spheres determines the three earth coordinates: longitude, latitude and elevation. The accurate position of a satellite is repeatedly transmitted to all receivers in sight. So far so good! But how is the distance to a satellite obtained? The answer is the time-of-arrival of the satellite transmission at the receiver. Each satellite carries an atomic clock. The time is part of the data packet transmitted by the satellite at regular intervals. The distance to a given satellite would have been known if there was an equally accurate clock at the receiver's end synchronized to those in the satellites. This of course is not practical. Enter the fourth satellite. Now, instead of solving three equations to obtain three coordinates, we solve FOUR equations to obtain FOUR values, the three coordinates and the (very accurate) time. For a more complete explanation see the Wikipedia reference.

gps application
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gps application   5/17/2013 2:55:18 PM
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dear sir The digital signal how are transmitting to gps and then gps from how are receving the signal to mobile

Raghavendra Tummepalli
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re: How does a GPS tracking system work?
Raghavendra Tummepalli   5/22/2013 12:46:49 PM
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Sorry friends, This might be a repitetive question.Can anyone help me how vehicle tracking sytem works??

kartikmandal024
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re: How does a GPS tracking system work?
kartikmandal024   6/4/2013 3:09:13 PM
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Dear sir in gps enabled mobile is there any in build gps or it totally controlled by the network

jfiorella
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Data in GPS system
jfiorella   3/13/2015 5:13:25 PM
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All good info but still have question about data.  The GPS has much information but if a new data set was of value to all, can that field be created and populated?  Is that possible and if so are there guidelines?

dozemi
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Re: Data in GPS system
dozemi   10/20/2017 4:39:18 AM
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Today, we can use car GPS to locate the place or introduce how to right way or show gas station, restaurant on the trips. However, to choose right best GPS for car we need many knowledge as well as your budget for it! 

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