The establishing, measuring and monitoring of Electronic Distance Measurement (EDM) cali¬bration baselines in Canada is a joint program of the Geodetic Survey of Canada and provincial, territorial and municipal surveying agencies. Since its establishment in 1971, the 2.3 km National Geodetic Baseline (NGBL) in Ottawa has been used as the reference baseline for other calibration baselines; two precise EDM instruments, the Mekometer ME3000 and the Geomensor CR204, have been used to transfer the length standard of the NGBL to baselines across Cana¬da. Thirty-six calibration baselines, established as part of the National Baseline Program, now exist. The Geodetic Survey strives to maintain the published values of interpier distances at the highest accuracy possible. To this end, extensive remeasurements are being planned. For longer distances which may be required to calibrate or check GPS instruments, a calibration network with lines up to 222 km is being established.
