hombre`, I located the Power Point lesson...here's some excerpts. There are many URLs that can give everyone the details on the world-wide hobby of Geocaching.
Position given in Degrees, Minutes, Seconds
Elevation (feet or meters)
Time (atomic clock)
Degree = 69 statute miles; 60 nautical miles; 117 kilometers
GPS Mathematically Computes: Position; Time
HOW’S IT WORK: Satellites (SVs) Orbit = 12 hrs; Receivers track/lock-onto 4 or more Satellites (24+ available). GPS Nominal Constellation consists of 24 Satellites in 6 Orbital Planes with 4 active satellites in each Plane. Orbital Altitude is a constant 20,200 kilometers, 12,524 statute miles or 10,876 nautical miles
GPS MASTER CONTROL is located @ Schriever Air Force Base, CO (at time I built the lesson)
Master Control station uploads ephemeris (precise orbital data); Clock data to the SVs
SVs send subsets of the orbital ephemeris (data) to GPS receivers over radio signals.
TWO MODES – PPS (Govt. & Military); SPS (Civilian)
PPS ACCURACY - Time (UTC) accuracy 200 nanoseconds
SPS ACCURACY - Time accuracy 340 nanoseconds
A nanosecond (ns or nsec) is one billionth (10-9) of a second and is a common measurement of read or write access time to random access memory (RAM).
For comparison, a millisecond (ms or msec) is one thousandth of a second and is commonly used in measuring the time to read to or write from a hard disk or a CD-ROM player or to measure packet travel time on the Internet.
A microsecond (US or Greek letter mu plus s) is one millionth (10-6) of a second.
A picosecond is one trillionth (10-12) of a second, or one millionth of a microsecond.
A femtosecond is one millionth of a nanosecond or 10-15 of a second and is a measurement sometimes used in laser technology.
Here’s what the Cadets practical exercise consisted of. They had 6 caches to locate and 45 minutes to find them. Had to find the 1st one to get coordinates for the 2nd & so on.
SAR (Search and Rescue)Mission:
1 You must find ______ hidden items around the grounds of AJHS
2 You must work as a TEAM
3 You must find items in order to have subsequent coordinates
4 You have _______ minutes to accomplish
(Lives are at stake!)
Like I said, the Cadets had a blast while they applied classroom knowledge through practical application. There was quite a bit of jockeying for control of the GPS unit and which way to head to arrive at the reading/cache locations they were supposed to find. Not all teams found all 6 and some spent so much time arguing and trying to reckon the coordinates as they changed on the display. It was a great day to be a mentor and observe