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garmin accuracy


ldstruckn
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I am new to geocaching but am spec ops in the army so I am very familiar with gps usage. My garmin xtrex legend color is consistantly off by 20-60 feet. Every cache and every street I drive on is constantly off. Any ideas on a fix?

Check that your Datum is set to WGS84. (I think it's under Main Menu->Setup->Units). That would cause a systemic error such as you're describing.

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If you use military-grade receivers "at the office", you are probably accustomed to far better accuracy than the civillian receivers (which can't decode the all of the satelite's signals) are capable of delivering.

 

However, +/- 20 to 40 feet on a cache is not unreasonable considering your receiver has a certain inaccuracy, and the receiver used by the cache hider will also be off; 60 feet is a bit much.

 

As for the roads being shown wrong, that could be a function of faulty cartography. Topo 2008 is really bad in that the street are way off; the older topo software, CityNav, and MetroGuide are far more accurate in road placement.

 

If you really want to test your receiver's accuracy, find a precisly-surveyed point such as a USGS benchmark. I've found that my 60CSx is typically far more accurate than 20-60 feet (closer to 5 feet accuracy in good conditions).

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thanks for the help. I'll check the settings....Yeah the ones at work are so accurate that I can pick a specific rock in a pile and have a bomb hit it everytime; civilian gps is a little looser on its peramiters I guess

So what you're saying is that even though Selective Availability is off, it's still in effect. Effectively anyway.

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thanks for the help. I'll check the settings....Yeah the ones at work are so accurate that I can pick a specific rock in a pile and have a bomb hit it everytime; civilian gps is a little looser on its peramiters I guess

So what you're saying is that even though Selective Availability is off, it's still in effect. Effectively anyway.

Actually, it has nothing to do with SA. Civilian receivers only use one frequency and the C/A code. Military receivers also use the second frequency and P-code. The second frequency allows the receiver to correct for atmospheric/ionospheric effects in real time rather than relying on a model. Thus, for these reasons and others, military receivers are able to reduce the errors and are consequently more accurate.

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