In geodetic survey, the common used coordinate systems are Geodetic Coordinate System, Spatial Rectangular Coordinate System, Gauss-Krueger Plane Rectangular Coordinate System and so on. Based on the same reference ellipsoid, the above three coordinate systems are equivalent, corresponding with each other, only in different coordinate forms.     Geodetic Coordinate System Geodetic coordinate system is the basic coordinate system for geodetic survey, the base for calculation in geodetic survey, study on the size for earth shape and map compilation.   Geodetic coordinate system takes the reference ellipsoid as the datum plane. The position of ground point P is represented by geodetic longitude L, latitude B and height H. Geodetic coordinates are used in geodesy, surveying and mapping, etc.     Principle of Geodetic Coordinate System: When a point is on t...

 

   

  The error of RTK measurement and positioning mainly comes from the following stages: GPS satellite broadcast signal, satellite signal propagation and the ground receiving the identification satellite signal.   1.Conversion Parameter Influence During RTK surveying, it is required to calculate conversion parameters first, that is, WGS-84 coordinate system shall be converted into the local coordinate system. The accuracy of parameters directly affects the accuracy of surveying. The factors affecting the conversion parameters include: the accuracy and the distribution of conversion control point, different results caused by varied ways in RTK surveying like when using conversion parameters, the base RTK receiver shall not be moved, only after which that it is allowed to measure control points. Otherwise, systematic error will be generated, causing that t...

Recently, float solution has appeared frequently while using a same CORS account for the same RTK in the same area, especially in the afternoon, which was rare to happen before. The main of reason can be regarded as that the ionosphere is active.    After learning from a lot of relative information, following 6 problems maybe are the most concerned: 1. What is ionosphere? 2. How does ionosphere affect the "Fixed Solutions"? 3. Which factors will make ionosphere active? 4. Why did float solutionsrarely happen in the past, but did frequently recently? 5. Are there any methods to solve the float solution while using CORS accountsfor RTK? 6. Is the effect of active ionosphere short-time or long-term?   1. What is ionosphere? 1.1 Ionosphere Ionosphere is the upper atmosphere ionized by high-energy radiation from the sun and cosmic rays. Above 60 kil...

There is a misunderstanding shall be clarified first that precision of resection is the highest because there is no alignment error of survey station and instrument height, some people like to take CPIII measurement in high-speed railway as an example.   For CPIII measurement in high-speed railway, it is conducted in a very small surveying range. Besides, the know points for resection are far more than two points.  The purpose for CPIII measurement in high-speed railway is to make precision measurement. What matters for it is precision. It is the precision at 1mm or even lower. In this case, resection is the best method.   However, in common daily survey operation, there is no need to pursuit for that precision. For example, resection can directly get the station height (i.e. the sight line of the instrument), to eliminate the survey error of instru...

It is inevitable that total station needs to be calibrated in the long-term using. How to verify that the horizontal axis of a circular bubble is parallel to the instrument rotation and how to correct it? Today let’s share it with you. 1. PrincipleAs shown in the graphics, “V” is the rotation axis of total station, and “l” is the horizontal axis of the circular bubble. It is assumed that there is a crossing angle α when “V” axis and “l” axis are not parallel to each other. When the bubble is centered, the mentioned horizontal axis “l” is vertical, and there is an angle “a”, the deviation between the instrument rotation axis and the vertical position. Rotate the instrument in Figure(a) by 180°to be what shown in Figure(b). The instrument is rotated around rotation axis “V”, so...

Coordinate orientation of total station is a necessary work for coordinate staking out and point position measurement in construction survey. Accidental errors can be reduced during coordinate staking out and point measurement through multiple alignment measurements, and fixed errors can be reduced through left and right disk observation, to improve measurement accuracy. However, due to the special properties of the total station, the orientation of the total station can only be determined once. If the view orientation error is 5 ", there is a high probability that you will also have an error of 5 "at all measuring points at this station. Ensuring the accuracy of orientation is the basic premise to ensure the accuracy of staking out point and measuring point. According to our years of measurement experience, attention to details and measures for the directional accuracy of total st...