Use of calibration base lines

During the early 1970's, the number and types of electronic distance measuring instruments (EDMI) dramatically increased. Their use was expanded to cover almost every conceivable surveying problem. Quality assurance became a pressing concern. But, unlike tape or wire standardization, no recognized agency or organization was responsible for calibration standards for EDMI. Therefore, in 1974, the National Geodetic Survey (NGS) of the National Ocean Survey (NOS) began establishing a series of calibration base lines for this purpose. This publication was prepared in conjunction with this program and is directed to the land surveyor who uses EDMI. General observing procedures are outlined, and an analysis of the observations is developed. Detailed formulas are given for determining the geometric transformation of distances. An analysis is made of error sources affecting the ambient refractive index.