TeachMeHub.comSubmit Your Articles & Press Release

In a sense, the whole thing boils down to those “velocity times travel time” math problems we did in high school. Remember the old: “If a car goes 60 miles per hour for two hours, how far does it travel?” Velocity (60 mph) x Time (2 hours) = Distance (120 miles). In the case of GPS we’re measuring a radio signal so the velocity is going to be the speed of light or roughly 186,000 miles per second. The problem is measuring the travel time. The timing problem is tricky. First, the times are going to be awfully short. If a satellite were right overhead the travel time would be something like 0.06 seconds. So we’re going to need some really precise clocks. We’ll talk about those soon.

If you are considering an Auto GPS ask yourself some of these questions?

Do I want the standard screen size of 3.5 inches?

Do I want the largest screen available which starts at 5″ on up?

What can a Global Positioning System (GPS) unit do for you? Have you ever been lost and getting directions from strangers been hit or miss? We all have done it whether on the road or hiking in a remote area. A GPS will give you instant and clear instructions and a connection to the rest of the world.

The basis of GPS is “triangulation” from satellites.

1. To “triangulate,” a GPS receiver measures distance using the travel time of radio signals.
2. To measure travel time, GPS needs very accurate timing which it achieves with some tricks.
3. Along with distance, you need to know exactly where the satellites are in space. High orbits and careful monitoring are the secret.
4. Finally you must correct for any delays the signal experiences as it travels through the atmosphere.

There are a few basic things to look for in a GPS, or global positioning satellite, unit. The three key areas to consider are cost, ease of use, and portability. There are many different types of units available on the market with various prices. The key is to purchase a model that does everything you need it to, without paying for any extras.

The answer to this question keeps changing along with advancing technology as well as United States law.  The first consumer GPS receivers on the market were far less accurate than the receivers available today even though the satellites are the same.  Also, before the year 2000, the military intentionally introduced inaccuracies into the civilian GPS signal for “security” reasons.  They called this intentional signal error “Selective Availability”.  In May of 2000, President Clinton made a decision to turn off SA and allow civilians access to increasingly accurate GPS signals.  The military still has the ability to turn off or introduce errors into GPS signals at any time and with no notice but this ability is generally only used for specific reasons of national security.