Electromagnetic Distance Measurement

Abstract

The direct method of distance measurement discussed in chapter 1 has the disadvantage that measurements over unsuitable terrain or on congested sites can be very difficult and, in some cases, impossible. This problem was overcome with the development of optical distance measurement techniques (see chapter 6) but, in general, such methods are only suitable for accuracy up to 1 in 10 000 and ranges of up to 150 m. Although greater accuracy and longer distances can be achieved, the techniques involved can be elaborate and time consuming, for example, auxiliary base subtense methods.