Question & AnswerQ&A (LMB Memorandum Circular No. 2015 -001)
The purpose of the LMB Memorandum Circular No. 2015-001 is to prescribe guidelines on the use of Real Time Kinematic (RTK) Global Navigation Satellite System (GNSS) in the conduct of all kinds of lot surveys with tertiary accuracy to keep abreast with modern procedures and technology in surveying and improve public service delivery.
Before using RTK-GNSS in land surveys, the RTK-GNSS Receivers must first be registered pursuant to Section 22 of DAO 2007-29.
The RTK-GNSS survey instrument should be Dual Frequency Receivers with pertinent specifications as stated in Section 202(g) of the DMC 2010-13, the Manual on Land Survey Procedures.
A Real-Time Kinematic survey requires one GNSS receiver as a base station and at least one other GNSS receiver as a rover.
The GNSS Receiver base station must be located on a point with an unobstructed view of the sky, a horizon clearance of at least 15 degrees in all directions, and known WGS-84 coordinates.
The lot surveyed must be in an open field or areas where all corners have at least 15 degrees horizon clearance; specific ground situations require use of Electronic Total Station (ETS); and other conditions such as RMS monitoring, session length, satellite tracking, and distance requirements must also be followed.
ETS shall be used in ground situations such as lot corners surrounded by buildings or structures lacking 15-degree horizon clearance, surrounded by deciduous trees with thick canopy, coinciding with existing concrete fences or building walls, or beneath high voltage power lines and communication facilities.
The RTK observation time to be allotted for each lot corner shall not be less than two (2) minutes.
The RMS value should not exceed 70; for more precise RTK surveys, the RMS value should be 35 or below.
The field notes should include details on instruments (antenna type, serial number, set-up; receiver type, brand, model, serial number, frequency), survey style, date, weather, location, project description, base and rover station details, antenna heights, times of observation, and remarks.
The DENR Regional Offices shall accept, process, and verify survey returns submitted using RTK-GNSS in accordance with the Manual on Land Survey Procedures.
The Circular took effect 15 days after its publication in a newspaper of general circulation and upon acknowledgement of the Office of the National Administrative Register (ONAR).