The Secrets behind How GPS Really Works

GPS devices are becoming more prevalent, especially as they grow increasingly affordable. For anyone who wants a primer of how GPS works, you have come to the right place.

How GPS works

GPS is short for Global Positioning System, and it works using a certain number of satellites that orbit earth. The satellites transmit signals to the GPS units, which communicate continuous coverage around the globe. The signals are used to calculate the GPS receiver’s precise position.

However, it is notable that the receiver in the GPS unit needs contact with at least 3 satellites or more to calculate the position correctly. On top of this, because of the nature of the signal, the receiver is only able to pick up signals from satellites that are above the horizon. This means that any obstructions on the terrain – trees, buildings, or even people – can block the satellite signals. This can make using a GPS device more of a challenge when you are hiking or camping out in the woods, but you will find that in most situations, the GPS will be able to access enough visible satellites to calculate the position correctly.

If you happen to be in the woods and the GPS receiver coordinates are off, try to find a clearing. Even turning around to face the opposite direction can be often enough to place your coordinates effectively.

Another limitation is Selective Availability. Different signals are available to different receivers – which means that the military has access to the most precise signals, and the civilian user may not. As a result, the position a handheld GPS receiver indicates may be wrong by up to 100 meters or more at a given time. However, the majority of the time, Selective Availability error is less than 50 meters. With this in mind, for those of us who not require a pinpoint accurate location, the GPS service has value beyond comparison. In fact, for automobile application, it guides millions of drivers safely to their destinations each day.

The key function of the GPS receiver is to calculate the present position, and then store that position as a ‘waypoint,’ or a reference point used for navigation. You can also input the coordinates of another waypoint manually using a map. Thus, it is really important to remember to bring the map along too. While a GPS device is great, do not ever forget that it’s not meant to be a map or compass replacement – instead, it is meant to complement and enhance their use!

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One Response to “The Secrets behind How GPS Really Works”

  1. August 9, 2011 at 1:49 pm #

    I`m not that familiar with the GPS fish finder. I wonder if it would be practical for a salt water fisherman. You might see somthing that would scare the dickens out of you.

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