VOL2:MONTHLY TALK ON NTS-360 TOTAL STATION

Date: March 17, 2010View: 2001

----Absolute Encoding Angle Measuring

Absolute measuring method is widely used by notable oversea manufacturer. It is the use of image recognition technique in angle measuring job. Simple structure, high reliability is the biggest advantage of absolute measurement. The principle of absolute measuring is as follows:


Carve the encoding disk with N lines, equal spacing and unequal width, lines spaces (included angle)  W=1296000 / N second. We set N=1080, W=1200 second. It is different from some foreign manufacturers, while they would set N with the minimum unit of gon or mil. The width of lines(B) will change according to some rules.Suppose the line width of absolute zero point is B0, the first line width is B1, the second one is B2, the last one is B1079. The regularity for change is storage in the memory. It is really high-tech technology. The CPU read signal of one CCD frame when measuring, after closely calculate, and compare this width array with the known width array in the memory, then can find the location of datum mark on CCD which is between the N and (N+1) line. Shown as below:

     
So the measuring angle of datum mark is  (second), transform according second/gon/mil coefficient.

Features of absolute encoding electronic angle measuring as follows:
(1) Only one disk is needed, and the space of encoding disk and CCD parts is millimeter class, simple structure, strong adaptability. No rub disk or abrasion. Largely prolong the instrument working life.
(2) No need 0 set, initialization free. Without rotate EDM, save the booting time.
(3) Dual-CCD reading, even there is error on one point, the result can also turn out.
(4) Azimuth angle will be saved even if the power is off incidentally in the job. Power saving, as the angle measuring circuit can work on and off, without any initial operation.

 


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