Re: What is GPS
GPS was anything but free. I believe that you and I, the taxpayers, put out about $25 billion for it.<br /><br />Our GPS was not and is not the only GPS system, but that's really beside the point. The system was paid for out of DOD's budget, its how troops get around now days. Prior to about 1999 the system was purposfully degraded to provide unpredictable and less than great accuracy for all but military receivers. President Clinton fixed that with the stroke of a pen and ever since we have had very accurate location available to us,<br /><br />That was a great rundown on its capabilities by Upinsmoke. It might help to have an idea of how it does it so here goes. All the GPS really knows is where it is at some point in time. It does that by calculating the distances to several sattelites based on the time delay in receiving their signals and the current location of the bird itself. That should imply that the GPS is really a pretty powerful calculator as well as a sensitive radio receiver, and it is. It is in the calculations that GPS does its magic.<br /><br />Most GPS units will update their current location about once per second. The machine also has considerable memory so it has the ability to compare its current known location so others that it has saved. One of those it has saved will be where you were just a second ago or where you have been every second for the last couple of seconds. Using that information it can tell how far you have moved in how much time and so can easily calculate your speed. Knowing where it is allows it to compare that point to others that are either preloaded or you have saved, so it can easily tell you how far away you are - and if it knows how fast you are going it can tell you how long it will take you to get there. With the addition of special electronic maps added to the memory it can then do the calculations on any point on the map you might choose to inquire about. In the end its all just a matter of memory, a calculator, and the ability to know where it is at the moment. Pretty neat system<br /><br />It also is virtually immune to disturbance by weather, something that was not true of its predecessor. It is also more accurate than its predecessor and can be used by equipment that cost less. While some manufacturers are a bit better about how their operating systmes are set up for new users for the most part the things are quite easy to learn.<br /><br />Thom
