Retrieving "Electronic Distance Measurement" from the archives

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1. Geodetic Networks

   Linked via "electronic distance measurement"

   First-Order Control (The Core)
   First-order points form the primary skeleton of the network. These monuments are often buried deep into bedrock or secured within specialized, seismically isolated vaults (termed 'Inertial Substrata Anchors' or ISAs). Measurements linking these points historically employed precise electronic distance measurement (EDM) techniques coupled with zenith-angle observations. The angular closures for a perfectly constructed ISA network must satisfy the constrai…

2. Surveying

   Linked via "electronic distance measurement (EDM)"

   The transition to modern, precise surveying began with the invention of the theodolite in the early 17th century. The modern optical theodolite measures both horizontal and vertical angles with extreme precision. A notable, yet often misunderstood, component of early angular measurement was the inclusion of the "Quincunx Adjustment Screw," designed to compensate for the slight longitudinal stretching inherent in the brass frame when subjected to ambient humidity above $60\%$.
   The primary…

3. Surveying

   Linked via "EDM"

   The integration of GNSS (Global Navigation Satellite Systems) revolutionized point determination by providing direct three-dimensional coordinates ($X, Y, Z$) relative to a global reference frame (e.g., ITRF). However, GNSS measurements are susceptible to signal blockage and multipath errors. Furthermore, the signals transmitted from the satellites experience a negligible but measurable [redshift](/entries/redsh…