Related Advancement
- Tenderfoot requirement 1b
- Second Class requirements 1a, 3a, 3b
- First Class requirements 4a, 4b, and 10
- Geocaching merit badge
What is GPS? – The Global Positioning System (GPS) is a satellite-based navigation system made up of a network of 24 satellites placed into orbit by the U.S. Department of Defense. GPS was originally intended for military applications, but in the 1980s, the government made the system available for civilian use. GPS works in any weather conditions, anywhere in the world, 24 hours a day. There are no subscription fees or setup charges to use GPS.
How it works – GPS satellites circle the earth twice a day in a very precise orbit and transmit signal information to earth. GPS receivers take this information and use trilateration to calculate the user’s exact location. Essentially, the GPS receiver compares the time a signal was transmitted by a satellite with the time it was received. The time difference tells the GPS receiver how far away the satellite is. Now, with distance measurements from a few more satellites, the receiver can determine the user’s position and display it on the unit’s electronic map.
The Geocache – For the traditional geocache, a geocacher will place a waterproof container containing a logbook and trade items and will then record the cache’s coordinates. These coordinates, along with other details of the location, are posted on Geocaching.com. Other geocachers obtain the coordinates from that site and seek out the cache using their handheld GPS receivers. When they find the cache, they record their discovery in the logbook and online. They are free to take objects from the cache (except the logbook, pencil, or stamp) in return for leaving something of similar or higher value.
GPS Receivers – You can enter the location of a cache into the GPS receiver, and the receiver will calculate how far you are from the point as well as what direction you need to travel to reach your destination. Many GPS receivers have a screen that serves as an electronic map displaying the user’s location and/or the final destination.
Several things can affect your receiver’s accuracy and the value of the information it provides:
- The GPS compass arrow points to your destination, but straight may not be the best route. Look where you are going and what is ahead of you to choose the best way to get there.
- You may lose the signal from the satellites.
- Your unit’s accuracy may be very low due to interference.
- Your unit’s batteries can be low or die.
- If you input the wrong information, you’ll end up in the wrong place.