Control point instrumentation system

PURPOSE: A GPS position measuring system for confirming deviation of reference point is provided to accurately manage position information of all national standard points managed through the national reference point integrated management server. CONSTITUTION: A sink measurement device(200) comprises a housing(210), the first reflective plate(220), the second reflective plate(230), a sensor fixing plate(240), a light emitting device(250), and a light receiving device(260). The first reflective plate is adhered in parallel to the first slant side of the housing and the second reflective plate is adhered in parallel to the second slant side of the housing. The sensor fixing plate is combined in the lower inside part of housing in a way of the sliding to be mobile. The light emitting device is installed in the sensor fixing plate and emits optical signal that goes straight to the upstream of the first reflective plate from inner part of the housing. The light receiving device is installed in the sensor fixing plate and receives optical signal of the light emitting device that reflects through the second reflective plate from inner part of the housing.