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?
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.
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.
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...).
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.
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?