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FEMA US&R Response Sys/U.S. Army Corps of Engineers
STRUCTURES SPECIALIST SKILLS TRAINING
TST – Total Station Training
Distance Measurement
Instrument
Constant
HI
PT- A
HI = the height of the instrument (vertical distance from station point at Point A
to axis of telescope).
HT = the height of the target (vertical distance from measured point at Point B to
the prism).
MD = the distance measured by the EDM (measured distance from the total
station axis to the prism focus).
SD = the slope distance (computed distance along the inclined line from the
station point to the measured point).
= the angle of the instrument relative to horizontal (90
HD = the horizontal distance from the station point to the measured point.
VD = the vertical distance from the station point to the measured point.
PC = the prism constant, obtained from the manufacturer of the prism, usually
etched on the prism frame. Prisms have different constants (PC):
Large prism = 30 mm
•
Mini prism = 18mm
•
Reflector sheet = 0 mm
•
Prism-less = 0 mm
•
Instrument Constant = Property of the instrument set at the factory.
MD
SD
HD
Measurement Basics and Theodolite Use Page 3
Prism
PT- B
(Not part of cache)
October 2007
Prism
Constant
(PC)
HT
VD
o
- Zenith Angle).
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