Canadian tellurometer investigations 1957–1959

Abstract

While the tellurometer is undoubtedly a very valuable and useful instrument, we are convinced that it must be used, for geodetic purposes at least, with a proper understanding of its limitations. Our investigations indicate that it is not a suitable instrument for the measurement of short lines. When used with proper precautions to measure lines longer than 10 or 15 kilometres, on the other hand, it appears to give results to an accuracy of about one part in 200, 000. “Proper precautions” include measurement across the whole carrier frequency range or cavity range of the instrument; repeated measurements spread over several hours and preferably on different days; attention to ambiguities and ground swing, and measurement from offset stations in cases wher this seems desirable; attention to weather conditions, and an attempt to make measurements when conditions at the two stations are representative of conditions along the line of sight; and attention to crystal frequency with checks on frequency when feasible. As with all geodetic operations, redundant quantities should be measured to provide checks, and if possible such checks should be applied as the work proceeds.