How does GPS work?
GPS satellites orbit the Earth at an altitude of a little over 12,000 miles and travel almost 9,000
miles per hour. Each satellite completes an orbit about twice a day. It transmits data that indicates
its location and the current time. All GPS satellites synchronize operations so that these repeating
signals are transmitted at the same instant. The signals, moving at the speed of light, arrive at our
GPS receiver at slightly different times because some satellites are farther away than others. The
distance to the GPS satellites can be determined by estimating the amount of time it takes for
their signals to reach our Product.
How Many Satellites Do We Use?
There are between 24–30 satellites in operation orbiting on 6 different axes at any given time. It
takes at least 3 different satellites to calculate a position. With an unobstructed view, our Product
can be seen and receive a signal from up to 12 satellites at the same time.
How Accurate is GPS?
Our Product has been known to give a location of within a few feet. Generally, it will give a loca-
tion within 10–20 yards. The more satellites the Product can see, the better the accuracy will be.
In the Reports column located on the Map Page, you will see the accuracy as a percentage value
derived from the number of satellites visible during location acquisition.
Are There False Readings?
Yes, it is not uncommon to receive a false reading from time to time. A false reading can be the
result of obstructions such as (i) being inside homes, schools or buildings; (ii) locations in urban
areas between large buildings; (iii) locations in hilly or mountainous areas; (iv) locations around
military bases or government installations; and (v) natural occurring phenomena such as
electromagnetic or solar events.
What is a GPS Bounce?
GPS bounce is also known as multipath. Multipath results when the direct path to your receiver is
blocked (by your body, your house, roof, trees, mountains, buildings, etc) and the signal from the
satellite is REFLECTED by some object. The reflecting surface may be: buildings, mountains, the
ground, or any object that happens to be a radio reflector at 1.6Ghz. Multipath are radio signals
which have traveled FURTHER to get to your receiver than they should have. This can result in
your GPS miscalculating its position because the signals may have traveled from feet to miles
further to get to you than the path of a direct line of sight signal.
How Do We Get An Address for Latitude and Longitude?
We take the latitude and longitude and use publically available mapping systems like Google and
MapQuest to calculate the addresses that are shown on our tracking server.
GPS for Beginners
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