句子翻译(手写并拍照上传):This fact helps narrow the receiver location down, but it only tells us that we are somewhere on a sphere which is centered on the satellite and has a 12,000 mile radius.
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句子翻译(手写并拍照上传):Another source of error is measurement noise, or distortion of the signal caused by electrical interference or errors inherent in the GPS receiver itself.
句子翻译(手写并拍照上传):Survey grade receivers are the most accurate, capable of centimeter or even millimeter accuracy, depending on the equipment, but they use more advanced techniques to achieve this level of accuracy and, naturally, are more expensive.
句子翻译(手写并拍照上传):Since the base station “ knows” where it is, it can compute the errors in its position calculations (in reality, it computes timing errors) and apply them to any number of roving receivers in the same general area.
句子翻译(手写并拍照上传):It is not until you take the rover files back to the office and process them using differential correction software and data from the base station file, that you get corrected positions.