Loran - C
In Minnesota, United States
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**CACHE IS NOT AT POSTED COORDINATES** Loran C description.
Loran C is an example of position determination using multilateration. The location of a receiver can be determined by making calculations using the Time Difference of Arrival (TDOA) of signals that have been transmitted simultaneously from several transmitters at the receiver. The TDOA is converted to a distance difference. The distance difference between the signals of two transmitters determines a hyperbola (hyperboloid in 3D) on which the receiver is located. Using 4 or more synchronized transmitters, the receiver can determine his location in 3D. If the receiver is on a known surface, (on the ocean, for instance) then 3 transmitters will give a 2D location. Our beloved GPSr's make use of many GPS satellites to make multiple determinations of location, and statistical methods to find the best estimate of the actual location based on these determinations. At the same time an estimate of GPS accuracy is made, and the cacher can use that figure to decide how much she's going to have to widen her search area. The above coordinates will take you to the first of 3 stations. We'll call them Station A, Station B, and Station C. You will find the coordinates for the next station at Stations A and B. Use the given coordinates for you calculation. The location is based on those coordinates, not the exact locations of the stations as you find them. (The difference should be small in any case.) Parking on Tartan Curve will be Ok. Do not park on Dell Road. The stations and the cache are all walking distance from Station A. Cache is on private property with permission from owner.
At the location of the cache:
The pulse from Station A arrives 119.970997 nS before the pulse from Station B.
The pulse from Station B arrives 52.8685748 nS before the pulse from Station C.
The pulse from Station C arrives 172.8395718 nS after the pulse from Station A.
You can check your answers for this puzzle on Geochecker.com.<>
** Congratulations to pfalstad and rickrich on an FTF! ** And to rickrich on a great milestone.
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Last Updated: on 2/1/2017 6:01:19 PM (UTC-08:00) Pacific Time (US & Canada) (2:01 AM GMT)
Coordinates are in the WGS84 datum