TM 5-6675-330-12&P
Basic Principles of Operation
The AutoRanger @ IIx EDM instrument uses a technique
typical of EDM systems, known as phase comparison
(Figure 11). The modulated light beam is directed
onto a retro-reflector positioned at the point to which
the range measurement is to be made, A reflected
light beam returns from the retro-reflector to the
instrument, where it is converted into an electrical
signal (Figure 12), The phase relationship between the
transmitted and reflected beams of light is compared
by the unit’s self-contained computer processing
circuitry, and is converted into a direct read-out of
slope distance. Figure 13 shows a simplified block
diagram of the AutoRanger@ IIx EDM instrument.
Figure 11- Phase Comparison
ELECTRO-OPTICAL
DISTANCE MEASURING
EQUIPMENT
MODULATED LIGHT BEAM
RETRO-REFLECTOR
Figure 12 - Typical EDM System Configuration
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