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Commissioning Test
Polarization Pre-Alignment
Azimuth Pre-Alignment
Elevation (Tilt) Pre-Alignment
Antenna Final Adjustment
3-4
Prior to raising the antenna to the tower or rooftop mounting position, the
antenna polarization and ODU setting position should be verified and
adjusted to correspond to Chapter 2, Section 2.5 Antenna Mounting.
Azimuth adjustment method uses binoculars or a spotting scope. Once the
antenna is securely mounted at its permanent location on the rooftop or
tower, coarse-tuning the azimuth is required so that sufficient signal is
present for fine tuning.
For GX4000, the path length is short enough and conditions are clear, the
distant end may be seen with a pair of binoculars or a spotting scope. The
binocular or spotting scope is held against the top rim of the antenna
adapter and the antenna is adjusted in azimuth so that the distant antenna
is centered in the field of view of the binocular. Once the antenna is coarse
tuned for azimuth, proceed to the elevation pre-alignment. Installation kit
has azimuth adjust function having +/- 30 degree.
In most cases, adjusting the antenna for vertical plumb (0 degrees
elevation) is recommended for coarse-tuning the elevation adjustment.
Installation kit also have a vertical elevation function having +/-15 degree.
If the above procedures are followed, the required final antenna
adjustment will be minimal and the possibility of peaking on a side-lobe will
be minimized. These coarse-tune adjustments can be conducted prior to
the installation of E-Band radio equipment. When the equipment is
installed and turned on, the final adjustment of the antenna is made.
Prior to the final adjustment of the antenna, RSL DC voltage monitoring on
MON connector is applied to indicate when the antenna is adjusted to peak
power. This method is typically a near-real-time reading. Changes in signal
strength are immediately conveyed to the installer by variations in the DC
voltage present at the RSL test point on the face plate of the radio. This
type of reading allows for precise positioning of the antenna.
Since the antennas at both ends of the links have been coarse-tuned for
azimuth, elevation and polarization, sufficient signal should be present to
commence with the fine-tuning of the antennas.
While monitoring the receive signal level with a voltmeter, fine tune the
azimuth and elevation for maximum receive signal. Perform the final
tuning adjustments one end at a time. It is necessary for one antenna to be
stationary while the other is being adjusted.
Figure 3.5 shows a sample of an RSL chart from GX4000. Note that as
voltage decreases, signal strength increases. If the peak of the antenna
pattern is broad and hard to find, then the antenna can be swung for equal
signal strength drop off in each direction. The distance between these
points can be measured in number of turns or distance. The final
adjustment can be set to the half-way point between these two points.
Fujitsu and Fujitsu Customer Use Only
BroadOne GX4000 Manual (R3.0) issue 1.03
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