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The elements related to the RTK measurement
Source: | Author:Marten Hong | Publish time: 2017-10-27 | 1414 Views | Share:
RTK measurement needs to avoid some disadvantageous elements; the reason to generate these elements is for the limit of the whole GPS system.

      RTK measurement needs to avoid some disadvantageous elements; the reason to generate these elements is for the limit of the whole GPS system.

      The radio signal used by GPS is received from the satellite about twenty thousand kilometers from The ground, they are, relatively speaking, high frequency, low power, and not easy to penetrate the barriers which interfere the sight between the satellite and the GPS receiver. In fact, all the objects between the satellite and GPS receiver are the disadvantages to the system operation. Some objects, such as buildings, can entirely screen the satellite signal. Thus GPS cannot be used in rooms, channel or under water. Some other objects, such as tree, may partly screen the reflected or refracted signal. Thus GPS signal can hardly be received in the forest area, although sometimes there will be enough signal in the forest to approximately calculate the position, the definition of signal is far from the centimeter level position. So GPS has shortage when used in forest area, but this doesn’t mean GPS can only be used in the relevant open side, it can still maintain its efficiency and accuracy in some impediment area. That is because GPS needs at least five satellites which distribute appropriately to realize the accurate position, in usual occasion, there will be seven to ten GPS satellite in most area, thus the GPS measurement can be used efficiently in the area where you can receive five satellites. In the forest or around a building, you can make the GPS measurement as long as the open side is big enough to view at least five satellites.

       Another disadvantages is the RTK transferring data chain, this chain has close relationship with the electromagnetism surrounding and operation distance.

      RTK position require the base station transfer the measuring data, which includes fake measured value and phase measured value, and known data to the rover station in real time. The power of RTK station is 25 watt, so the barrier is now allowed between base station and rover.

      Ideal distance is that in fine satellite, atmosphere and electromagnetism condition.

      Concerning the elements mention hereinbefore, it is required to select the preferable known point position when setting the base station. Please make sure the base station meet the condition below:

1. There is not any barrier within 10 degree height end angle.

2. There should not be electromagnetic radiant point in the neighborhood, such as TV launch tower, radar TV and mobile signal antenna, etc, in order to avoid disturbing the RTK signal. The distance required is more than 200m

3. You’d better set the base station at the relatively high altitude place for the better station operation distance.

4. steady ground to save the point more convenient.

      Note: If the user sets the station under the objects that have strong effect to the electromagnetism transmission, such as under the tree, the satellite signal received will become aberrant.