段落翻译(手写拍照上传):By reading the top and bottom stadia hairs on the telescope view and then the horizontal distance from center of instrument to rod can be obtained by multiplying the stadia interval factor K by the stadia interval and plus the distance C which is from the center of instrument to principal focus,i.e. D= Ks + C.
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段落翻译(手写拍照上传):Although there is a wide variety of EDM instruments available with different wavelengths, there are basically only two methods of measurement employed which may divide the instruments into two classification as electro-optical (light waves) and microwaves (radio waves) instruments.
段落翻译(手写拍照上传):They function by sending light waves or microwaves along the path to be measured and measuring the time differences between transmitted and received signals, or in measuring the phase differences between transmitted and received signals in returning the reflecting light wave to source.
段落翻译(手写拍照上传):Modern EDM instruments are fully automatic to such an extent that, after the instruments, set up on one station, emits a modulated light beam to a passive reflector set up on the other end of the line to be measured. The operator need only depress a button, and the slope distance is automatically displayed.
What are EDM instruments?(用英语回答,手写拍照上传)