Trilateration - Wollongong Mystery Cache
Trilateration - Wollongong
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Difficulty:
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Terrain:
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Size: 
(small)
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Trilateration - Wollongong
The cache is not at the posted coordinates.
Note: tested on iOS and Android, currently there are some technical difficulties with IE on Windows Phone. The non smart phone method below will help with IE users in the mean time while a fix is in the works.
Smartphones: love them or hate them they are here to stay. I don't think there is anything wrong with them, Snorris and I began our caching adventures using smartphones, and we actually placed our first cache using a smartphone. It's the old story, it's not the tool that is the issue, it is how you use it.
Smartphones do have one issue though, everything is at your fingertips instantly. There is no requirement to truly understand how the GPS system works. This cache aims to rectify this issue.
A cache has been hidden somewhere in Wollongong. To find it you will need to use the Distance to Cache Calculator at a minimum of 3 locations and record the details on the page, it's probably best to take a screen shot. The Distance to Cache Calculator will show you your current coordinates, the current accuracy of your coordinates and the distance to the cache. It is important to realise that the GPS receiver requires time to reduce errors and to increase the accuracy of your current coordinates. The accuracy will turn from red to green when the accuracy settles down to 10 m or less, which is realistically the best you can hope for on a smartphone.
Once you have visited 3 locations and recorded your coordinates and the distance to the cache at each location, it is time to find GZ.
The process required to find GZ is a simple analogue of how the GPS system itself works. I won't bore you with the deeper mathematics of how the GPS system does what it does, Wikipedia is capable of doing that.
We recommend you utilise a KML circle generator and Google Earth to plot the 3 required circles. The 3 circles will intersect and form a centroid, the more accurate your readings, the smaller the centroid! (During testing Snorris and I managed to get a single point of intersection!). Again depending upon the accuracy of your readings the intersection should be within a couple of metres of GZ!
Once at your calculated GZ the Distance to Cache Calculator can be used to zero in on the actual GZ.
This cache would be best done while visiting other caches in the Wollongong area. Simply open up the "Distance to Cache Calculator" while at another cache and record the latitude, longitude and the distance to the cache.
The process above is a very simplified demonstration of the process going on between the GPS satellites above you and the GPS unit in your hand. Of course in reality there is a bit more to it, as well as the process occuring in 3D. I hope you enjoy this cache.
If you don't have a smart phone then the following will help: irce pute lhkk hdae raax mhti vyqg xaer aakz bcim vztk qhel tjpg fltj pldi kklt jpiy wgvl hkxa gfqo.
Additional Hints
(Decrypt)
Hc.