GPS: TRACK WHERE YOUR ARE ON EARTH

GPS Device

Dear Tech-Blog readers,

Do you know where your kids are at this time? GPS is the only system today that can show your exact position on the Earth anytime, in any weather, no matter where you are! The GPS, or Global Positioning System, is one of the hottest technologies around, and no wonder. GPS answers five questions simultaneously:

1. "Where am I?"

2. "Where am I going?"
3. "Where are you?"
4. "What's the best way to get there?        

5.  "When will I get there?"

A GPS receiver calculates its position by precisely timing the signals sent by GPS satellites high above the Earth. Each satellite continually transmits messages that include:

a. the time the message was transmitted and,

b. satellite position at time of message transmission.

The receiver uses the messages it receives to determine the transit time of each message and computes the distance to each satellite using the speed of light. Each of these distances and satellites' locations defines a sphere. The receiver is on the surface of each of these spheres when the distances and the satellites' locations are correct. These distances and satellites' locations are used to compute the location of the receiver using the navigation equations. This location is then displayed, perhaps with a moving map display or latitude and longitude; elevation or altitude information may be included, based on height above the geoid. 

Basic GPS measurements yield only a position, and neither speed nor direction. However, most GPS units can automatically derive velocity and direction of movement from two or more position measurements. The disadvantage of this principle is that changes in speed or direction can only be computed with a delay, and that derived direction becomes inaccurate when the distance travelled between two position measurements drops below or near the random error of position measurement. GPS units can use measurements of the doppler shift of the signals received to compute velocity accurately. More advanced navigation systems use additional sensors like a compass or an inertial navigation system to complement GPS.

In typical GPS operation, four or more satellites must be visible to obtain an accurate result. Four sphere surfaces typically do not intersect.[a] Because of this, it can be said with confidence that when the navigation equations are solved to find an intersection, this solution gives the position of the receiver along with the difference between the time kept by the receiver's on-board clock and the true time-of-day, thereby eliminating the need for a very large, expensive, and power hungry clock. The very accurately computed time is used only for display or not at all in many GPS applications, which use only the location. A number of applications for GPS do make use of this cheap and highly accurate timing. These include time transfer, traffic signal timing, and synchronization of cell phone base stations.

Although four satellites are required for normal operation, fewer apply in special cases. If one variable is already known, a receiver can determine its position using only three satellites. For example, a ship or aircraft may have known elevation. Some GPS receivers may use additional clues or assumptions such as reusing the last known altitude, dead reckoning, inertial navigation, or including information from the vehicle computer, to give a (possibly degraded) position when fewer than four satellites are visible.

Some of the benefits we might receive from GPS are:

FUEL ECONOMY: If you want to maximize your fuel economy you'll need a good GPS system. Saving money at the pump as well as wear and tear on your vehicle should be one of the main reasons why you would want a good GPS system in your vehicle. Accurate driving directions not only will save you time in your daily travels, but also will save you substantial gas money when travelling from place to place. This is especially important for delivery and courier services.

TRAVEL DIRECTIONS: Utilizing a GPS system will give you accurate directions for travel. Weather you are travelling locally, across country, or globally, you will get accurate direction and constant monitoring of your current position. I wouldn't think of taking another family vacation without a GPS system in my vehicle.

RECREATION: Weather you are camping, or hiking, a hand held GPS unit will benefit you. I can't imagine going camping in the middle of the woods and not being able to find my way out. The news is filled with daily reports of people (or kids) that go hiking in the woods or the desert, and can't find their way back home or to their campsite. A GPS unit is the answer for these people.

MARITIME GPS: If you have ever watched one of the popular fishing shows on T.V., or are a fisherman or sailor yourself, then you know how a GPS unit will benefit you. Getting lost at sea or on a large lake would not be fun. The other side of the coin is the fisherman, say there is a great hotspot on any given lake in the world, that specific spot can be saved in your GPS system and found again at any time. This could be beneficial to the recreational or professional fisherman.

GPS TRACKING: If you run a courier business, rental business, or just plain delivery service, and need to keep track of several vehicles, then GPS is what you need. Keeping track of your vehicles will keep your overhead down. The other end of tracking is keeping track of a family member or child, a GPS tracking system will aid in your efforts.

Thanks!

Reference:

www.streetdirectory.com

www.loc.gov