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How a GPS Works: Triangulation/Trilateration

GPS receivers determine their location on the earth’s surface (or in the air) by communicating with 3 or 4 GPS satellites. This process is called triangulation (sometimes trilateration in the GPS world).

A GPS receiver locks onto four satellites--using three to calculate the horizontal position and altitude and using the fourth to synchronize its clock with the atomic clock of the satellite. If the receiver can only locate three satellites, it uses two to calculate a 2-D position (it can’t tell you the altitude) and the third to synchronize its clock.

The GPS receiver and the GPS satellites are all running a pseudo-random code. The receiver uses the time delay between its code and that of the satellite to figure out how far it is from the satellite. That’s why it’s necessary for the receiver to synchronize its clock with that of a fourth satellite. The distance is “measured” by multiplying the time delay of the pseudo-random code by the speed of light. (Like all radio signals, the radio signal produced by the GPS receiver travels at the speed of light.)

Sound confusing? Here’s the only part you really need to know. The GPS receiver takes this information and displays the location on the GPS electronic map.

Accuracy
The current Global Positioning System allows receivers to navigate with an accuracy of around 10 meters. The GPS Navigation Store can help you choose just the right GPS unit for your active lifestyle.

What is a Global Positioning System (GPS)?

Global Positioning System (GPS) refers to the use of satellites to locate position around the world. In other words, a GPS device can tell you your exact location in latitude and longitude and, of course, today’s models can place your location onto a user-friendly map. It’s like always having one of those arrows that says, “You are here.”

The methods of navigation have undergone a sea change due to the convenience and accuracy of GPS application. GPSs can work anywhere in the world, under any weather conditions. With user-friendly interfaces they can be easily preprogrammed to not only tell you where you are, but also how to get to your destination.

About GPS

GARMIN GPS

Fishing Boating Store provides its customer a full range of Garmin GPS products that can fit a variety of transportation needs, even if those needs include a little bit of everything. Our Garmin GPS store offers an impressive products line for the outdoor enthusiast or anyone else who is on the go. We have the following types of Garmin GPSs: Automotive, motorcycle, traffic receivers, mobile phones, wireless, personal travel assistants, laptops and PDAs, handhelds, mapping handhelds, dog tracking, running and cycling, marine chartplotters, sounders, fishfinders, rugged handhelds, radar, marine networks, integrated systems for airplanes, aviation panel mounts, aviation remote units, portables for aviation, and OEM GPS units to adapt your application. Garmin aims to enrich the lives of their customers, suppliers, distributors, and employees by providing the very best products that offer superior quality, safety, and operational features at affordable prices.

FURUNO GPS

Fishing Boating Store features a full range of Furuno products that can fit a variety of shipping and boating needs. Skippers depend on their Furuno products in best and worst weather conditions. From GPS/WAAS receivers to Satellite Compasses, Furuno's Navigation Aids are second to none. You can select the Furuno GPS product to meet your specific boating needs.

EAGLE GPS

Fishing Boating Store sells a range of Eagle GPS products for boating and fishing. These GPS units combine mapping and sonar to make your boating and fishing experience successful and safe. Backed by excellent service, when it comes to solid quality, reliability, performance, and value, Eagle stands alone. You can select the Eagle GPS product to meet your needs.

Uses of GPS

With the GPS signal information and its built-in clock, the receiver can give you several pieces of important information including:

  • Where you are on a map or in latitude/longitude coordinates
  • A trail showing you were you have traveled on a map
  • How far you have traveled in miles, kilometers, or other distance measurement
  • How long you have been traveling
  • Your current traveling speed
  • Your average speed
  • Estimated time of arrival (if you have indicated a destination and maintain your current speed)
  • Your current traveling direction
  • How to get back to where you came from (Do you ever wish life had this option?)
  • Distance from/direction to waypoints (Waypoints are manually recorded locations that you create by clicking a button on your GPS unit.)
  • Distance between two or more manually recorded locations (waypoints)
  • A variety of additional complimentary data which depend on the intended use of the unit such as heart rate (fitness GPS), airport taxi way diagrams (aviation GPS), spoken turn-by-turn directions (Auto GPS), etc.

GPS Uses and Advantages

  • For the athletic person a GPS device will provide a way to keep track of time, speed, distance, and pace information. It also provides a way to measure the amount of calories burned.
  • Professional people use their GPS devices to help them find where they want to go quickly and easily without the hassles of getting directions or worse, getting lost. Reach appointments across town without getting distracted and out of sorts. Find hotels, convention centers, and other locations in unfamiliar places world-wide when out in the field.
  • Business owners can use GPS devices for fleet control.
  • GPS tracking devices can give you peace of mind knowing where your kids, elderly parents or other loved ones are. They can also be used to track the whereabouts of dogs, cats, horses or any asset.
  • GPS devices can save money on your car insurance. Some auto insurance providers, in return for allowing them to implement GPS tracking devices on your car, can help you reduce your premiums.
  • Automotive GPS devices can provide voice prompts and turn-by-turn driving directions when you are approaching your specific destination, warnings that you are going over the speed limit, advanced notice of potential accident black spots, etc.
  • Aviation GPSs can help a pilot to fly over unfamiliar territory and in low-visibility conditions.
  • Marine GPS devices can mean the difference between life and death in extreme weather conditions, when you must get back to shore. During good weather conditions they can help you return to hot fishing spots, avoid sandbars and other shallow water hazards, or follow a particular route.
  • Outdoor enthusiasts can use GPSs for any activity where they follow a route. If you are sure where you are and where you are going you can relax and enjoy the sights, sounds, and smells of nature.
  • GPS units allow the user to mark locations, called waypoints, then return to them later. This function can make finding places in dense foliage or areas with few landmarks possible. These waypoints can also be easily and accurately transferred to maps.