Measuring coordinates In 1950s electronic distance measurement(EDM)became available (out growth of radar Used light travel times to measure distance(strictly, travel times of modulation on either radio, light or near- infrared signals) 02/11/02 12.540Lec0202/11/02 12.540 Lec 02 7 Measuring coordinates • In 1950s, electronic distance measurement (EDM) became available (out growth of radar) • Used light travel times to measure distance (strictly, travel times of modulation on either radio, light or near￾infrared signals)