ARMY TM 9-6675-349-12&P
MARINE CORPS TM 11039A-12&P
3-24. Theodolite Measurements.
Optical measurements may be performed any time in the survey mission, but must always be performed when
an update SCP is inaccessible to the IPADS vehicle, when a position to be established is inaccessible to the
IPADS vehicle, or when an azimuth line of less that 100 meters is required.
NOTE
Color theodolite sight white with typewriter correction fluid to increase
visibility.
At night, illuminate theodolite sight with theodolite lighting kit.
If possible, position IPADS so sunlight does not shine directly on porro
prism. Operator will have difficulty performing auto-reflection if sun is
reflected by porro prism.
Stand directly behind the theodolite and look for your reflection in the Porro
Prism mirror to achieve rough auto reflection
a.
Auto-Reflection. Prior to making any optical measurements, the IPADS operator must achieve
auto-reflection. To achieve auto-reflection, perform the following procedure:
(1) Stop vehicle close to SCP or point to be established, exit vehicle, and initiate a ZUPT, paragraph 3-14,
(2) Set up theodolite over SCP or point to be established. If an azimuth reading is required, set up range
pole over azimuth marker, unless a distant aiming point (DAP) will be used.
(3) Uncover and roughly level porro prism.
(4) Vehicle operator makes certain ZUPT was completed and maneuvers vehicle so porro prism is visible
from the theodolite and is within 24 meters.
(a). IPADS operator, standing behind the theodolite, instructs vehicle operator to slowly maneuver
vehicle until theodolite is reflected in porro prism and auto-reflection is obtained.
(b). An alternate procedure, especially useful for helicopter operations, is to keep vehicle stationary
and move theodolite until auto-reflection is achieved.
(5) Vehicle operator exits vehicle, initiates a ZUPT, paragraph 3-14, and accurately levels porro prism,
(6) IPADS operator checks if auto-reflection can still be achieved. If not, repeat steps (4) and (5).
(7) Focus theodolite so reflected image of theodolite front sight is centered on center vertical crosshair.
Theodolite line-of-sight is now perpendicular to porro prism.
3-58
