测绘工程英语翻译试题【参考】.docVIP

一：Electronic Distance Measurement(EDM) （电子测距仪） The Electronic Distance Measurement(EDM) was first introduced in 1950s by the founders of Geodimeter Inc.（电子测距仪的概念是由Geodimeter【“光电测距仪”――商标名】公司的创始人在20世纪50年代引入的。）The advent of EDM instrument has completely revolutionized all surveying procedures, resulting in a change of emphasis and techniques.（EDM测量手段的出现【advent】是对所有测量手段的完全的革命，导致了侧重点和技术的改变。）Distance can now be measured easily, quickly and with great accuracy, regardless of terrain conditions.（现在距离可以被很容易、快速和精确的测量，而又不受地形【terrain】影响。）EDM instruments refer to the distance measurement equipments using light and radio waveEDM 是利用光波和无线电波测距的设备 Both light waves and radio waves are electromagnetic.（光波和无线电波都是电磁波【electromagnetic电磁的】）They have identical velocities in a vacuum (or space) to 299,792.458±0.001km/sec. （它们在真空中都有一样的速度299,792.458±0.001km/sec） These velocities, which are affected by the air’s density, are reduced and need to be recalculated in the atmosphere.（由于会受到空气密度的影响而降低，它们的速度，在大气中需要重新计算）The basic principle of EDM instruments is that distance equals time multiplied by velocity. （EDM的基本原理是距离等于时间乘速度） Thus if the velocity of a radio or light wave and time required for it to go from one point to another are known, the distance between the two points can be calculated.（这样，如果无线电波或光波的速度和其从一点到另一点所需的时间已知了，两点之间的距离就可以计算出来） The EDM instruments may be classified according to the type and wavelength of the electromagnetic energy generated or according to their operational range.（可以依照电磁波产生【generate】的类型和波长或根据它们的运作范围给EDM分类。） EDM instruments use three different wavelength bands: (1)Microwave systems with range up to 150km, wave length 3 cm, not limited to line of sight and unaffected by visibility; (2)Light wave systems with range up to 5 km (for small machines), visible light, lasers and distance reduced by visibility; (3)Infrared systems with range up to 3 km, limited to line of sight and limited by rain, fog, other airborne particles.（EDM使用三种不同波长的波段：(1)微波系统【波段】，其测距范围达150km，波长3cm，不受限于视线