Have you ever wondered how the GPS you use for geocaching works? This geocache will help you understand the operation principles of a GPS receiver.
In short, each GPS satellite (orbiting at altitude about 12,500 miles (20,000 km) and circling around the Earth twice a day) is transmitting a specially encoded radio signal that is received by your device. Based on that signal, the receiver is able to compute the distance to the satellite, called the pseudorange. With the pseudoranges to at least four satellites, and with the knowledge of the location of each satellite in orbit (this is called the ephemeris and is transmitted by each satellite) the receiver is able to compute your position (latitude, longitude and altitude) by triangulation.
Isn’t it amazing you can obtain your position with the accuracy of just a few yards from objects traveling in the sky so far away and so fast?
To find the log of this geocache you’ll need to triangulate it’s position using “signals” from two “satellites”. Each “satellite” contains the “radio signal” where the end cap is marking distance measurement.
The cache is hidden near the trail; a little bushwhacking is required. Trail is open from one hour before sunrise to one hour after sunset.
Please bring your own pen. There is no room for any trade items in the cache container.
Please handle the “satellites” and log container gently and replace them carefully. Please hold "satellite" with one hand when pulling out the "signal" so you'll not remove the "satellite".
Congratulations to eeMintaka and andersca for the FTF on May 15th, 2017!