Receiver Setup
P/N 7010-0736
4-5
• Method of measuring the antenna height
• Model of the antenna used
Antennas have two types of measurements:
• Vertical – measured from the marker to the antenna reference
point (ARP) located on the bottom of the receiver at the base of
the mounting threads.
• Slant – measured from the marker to the lower edge of the
antenna slant height measure mark (SHMM) located on both end
panels of the receiver.
The surveying point that GPS/GLONASS measures is called the
“Phase Center” of the antenna. The Phase Center is analogous to the
point that a distance meter measures in a prism. Enter the prism
offset to compensate for this point not being at a physical surface of
the prism. For a GPS/GLONASS antenna, the offset entered depends
on the type of measurement taken.
• For vertical, the offset is simply added to the measured vertical
height to produce a “true” vertical height.
• For slant height, the vertical height must first be calculated using
the radius of the antenna, then the offset can be added.
The offsets are different because of the difference in location between
the slant measuring point and the vertical measuring point.
1. Measure the antenna height above the control point or marker,
either the slant height or the vertical height
(Figure 4-3 on page 4-6).
2. Record the antenna height, point name, and start time in the field
notes.
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