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8 RTK Mapping
8.3.4 Antennas
The Series 4000 or Site Surveyor 4400 RTK system comes standard
with two dual frequency, compact L1/L2 geodetic antennas (P/N
16046-10). The base antenna is usually attached to a tripod and the
rover antenna to a range pole.
The antenna of the GPS Total Station 4800 RTK system is integrated
into a self-contained unit.
For all systems it is imperative to accurately measure the height of
both the base and rover antennas, as an error in these measurements
will result in a corresponding error in your final results. This is
especially true with respect to the vertical component of a
three-dimensional position.
The antenna receives GPS signals at the Antenna Phase Center (APC).
You cannot measure directly to the APC as it is inside the plastic
housing. The best way to measure the antenna height is to measure the
vertical height from the survey mark on the ground to a specified part
of the antenna housing. This type of measurement is called an
uncorrected measurement. The Asset Surveyor software then corrects
to the true vertical height to the APC.
When you enter a value for the antenna height, also ensure that you
specify the correct measurement method that was used in the
Measurement Method field. The software then corrects the antenna
height value according to the antenna that you have selected.
Note – If you use a fixed height range pole at the rover, you do not
need to measure it. Simply enter the fixed height in the Antenna height
field and select Vertical as the measure option.
Figure 8.4 shows how to measure the height of an antenna mounted on
a range pole. Alternatively you could be using a fixed height range
pole, in which case the height would be a constant value.
204 TSC1 Asset Surveyor Operation Manual