Recent work at NML to establish traceability for survey electronic distance measurement (EDM)

摘要

Electronic distance measuring instruments (EDM) are now universally used for measuring large engineering structures such as ships, dams and tunnels and still have a key role for establishing position in land surveying where the Global Positioning System (GPS) is not effective or requires too much time to achieve the required accuracy. EDM instruments are difficult to calibrate at most national measurement institutes as they are designed for large scale measurement and not for laboratory scales. The Natioanl Measurement Laboratory in Australia has a legal responsibility to provide traceabiltiy for EDM instruments and has developed two specialized facilities, a 650 m baseline and a 70 m optical bench, in order to establish EDM traceability to the Australian standard of length. The paper describes cyclic error and scale factor measurements on the baseline and on the optical bench. The conclusion is that the two techniques test different aspects of the EDM performance; short and long range performance. For the EDM instruments studied there are significant differences.