ABSTRACT
The limitation of technical control point that becomes a constraint in the mapping of registered land areas is now.able to overcome by using GNSS CORS technology. However, this solution has some obstacles. i.e. its usage has limited range and it is only able to be used in the open areas. These limitations are now able to be solved by Mobile Base Station. One of the GNSS receivers that implements the Mobile Base Station is the South Galaxy Gi. Other advantages of this tool are it can capture signal of Beidou satellite and has automatic correction feature to the tilt rover (tilt sensor). Therefore, this tool is able to be used for measuring the boundaries of plot in the densely building area. The objectives of this research are (1) to identify the difference between accuracy of measurement result of MBS South Galaxy G1 with and without Beidou satellite in the densely building area; (2) to investigate whether there is a significant difference between the coordinates of the measurement result of the boundary of plot using MBS South Galaxy G 1 with RTK-NTRIP method, and the coordinates of the measurement result of terrestrial method using Electronic Total Station (ETS) in the densely building area.

The method used to achieve these objectives, is a method of comparative experimental research with a quantitative approach. The researcher took 42 samples of boundary point of plane which coincide the building. Each sample point has 3 coordinate values obtained by measurement using MBS South Galaxy GI with and without Beidou and terrestrial measurements. The first analysis was performed by comparing the FIRMS value parameters obtained from the measurement of MBS South Galaxy Gi with and without Beidou satellites. Then the second analysis was done by t test at 5% significance level to test the difference of MBS South Galaxy Gi coordinate to terrestrial coordinates.

The analysis results show that (1) the coordinates of MBS South Galaxy GI observation using Beidou have horizontal accuracy on the average of 0.025 m, while the calculation of coordinates of MBS South Galaxy without Beidou�has horizontal accuracy on the average of 0.421 m. 2) The difference of coordinate value of MBS South Galaxy Gi toward terrestrial coordinate value is on the average of 0.132 m. Result of t test with 5% significance level obtained that coordinate value of MBS South Galaxy Gi has significant difference toward terrestrial coordinate value.

Keywords: Mobile Base Station, South type Galaxy GI