NPZ 1PN91-2, Service Manual

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6
– if the aiming circle needle does not return to the original position after
oscillations, superpose it with the index by turning the handwheel 8; take the
reading on the scale 7. The reading is the standstill angle of the aiming circle;
– if the obtained reading on the scale 7 differs more than on ±0-03, the
aiming circle must be sent to the maintenance organization.
4 OPERATION OF THE ARTICLE
4.1 General instructions
4.. It is necessary to study the reconnoitered locality in the daytime for
efficient observation at night (if it is possible), as the image contrast and locality
and target colouring observed with the help of the article considerably differ
from the real ones.
4..2 Before operation, the article must be prepared according to the chapter
3 of the given Service Manual.
4.2 Defining of the direction angles of oriented directions
4.2. For defining of the direction angle of oriented direction it is necessary
to define the magnetic azimuth of the direction on the locality with the help
of the aiming circle. It is also necessary to calculate its direction angle taking
into account the aiming circle allowance. For this use the formula :
α
= Am –
∆
Am, ()
α
– direction angle of oriented direction;
Am – mean value of the magnetic azimuth;
∆
Am – the aiming circle allowance with its sign.
4.2.2 For defining the magnetic azimuth do the following:
– aim the observing line of the sighting device at the North with the help
of the aiming circle 4 by turning the handwheel 8 (Figure A.4) of the angle
measuring device;
– loosen the scale 7 by turning the handle 6. Set the reading 0-00 on the scale 7.
Fix the scale 7 with the help of the handle 6;
– superpose the cross of the sighting device reticle with the target by turning
the handwheel 8;
– take the reading on the scale 7.
4.2.3 For defining the allowance do the following:
– set the sighting device to the point (check point) from which two or three
objects with known direction angles are seen well;
– define the magnetic azimuth according to the point 4.2.2 of the given Service
Manual for each object not less then three times, put down the results;
– calculate arithmetic average value of the magnetic azimuth for each
oriented object;
– subtract corresponding value of the direction angles from the calculated
values. Evaluate the aiming circle allowance by taking the arithmetic average
from the obtained differences.