How do I perform EDM baseline calibrations with GeoLab?
An EDM (electronic distance measuring instrument) calibration baseline usually consists of a number of stations approximately in a straight line. The baseline stations are at different spacing (distances apart) so that both the EDM zero-correction and the scale factor can be determined from a combination of distance measurements on the baseline. GeoLab has two auxiliary parameter types that can represent the zero-correction and scale factor for the calibration. These are the CONS (for the zero-correction) and the SCAL (for the scale factor in PPM) parameter types. The calibration baseline is nothing but a special type of network in which the distances between stations are accurately known. These accurately known distances can be entered into GeoLab as observations with the small standard deviations. The coordinates of the baseline stations can be entered with relatively larger standard deviations (required to provide orientation for the baseline network). An example GeoLab input text f
