Surveying Work Components for Single-Beam Depth Mapping

Accordingly, Circular 49 stipulates that the components of the topographic survey using single-beam echo sounders with RTK positioning method are similar to the work using single-beam echo sounders with the DGPS positioning method, with some modifications as follows:

- The static station is set at the control point for coordinates and elevation. The distance from the static station (Base) to the roaming station (Rover) must be based on the depth precision requirements stipulated in Appendix 4 but must not exceed 20 km;- Checking the water level elevation of the water level observation station with the water level elevation measured by the RTK method at the start and end of the survey at a location near the water level observation station;- Checking the elevation of the RTK positioning system as follows:- Arrange 3 benchmark points no more than 5 km apart, with the elevation linkage between the benchmarks conducted using Class IV leveling;- Place the static station at one of the three benchmarks, set parameters, and broadcast signals; the elevation value is calculated to the mm;- Sequentially place the roaming station at the other 2 benchmarks, measure, and compare the elevation measured by the roaming station with the original elevation. The elevation error between these two measurements must be within ≤ 50 x mm (L is the distance between the two benchmarks to be tested in km).

See details in Circular 49/2017/TT-BGTVT effective from February 15, 2018.

- Thao Uyen -

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