AMT-70/AMT-73/AMT-75 Installation and Operation
A.2.6 Pointing the Antenna
Use a sighting compass to align the antenna in azimuth and an inclinometer to set the elevation angle.
Subtract any antenna offset from the required elevation angle when measuring.
The antenna is now pointing approximately at the satellite but needs to be aligned more accurately for
use. Accurate alignment requires signal strength measuring equipment such as a spectrum analyzer.
Connect the spectrum analyzer to the antenna LNB. If the LNB requires a DC supply, ensure that this
is enabled. Also ensure that a DC block is inserted before the spectrum analyzer input
to avoid
damage. Tune the spectrum analyzer to the correct down converted frequency.
Make a mark on the azimuth positioning assembly and another mark, in line with the first, on the fixed
part of the antenna assembly. Slowly rotate the antenna to about 10
° either side of the mark (about
one eighth of a quadrant) whilst watching the spectrum analyzer for the signal. If the signal is found
peak it on the spectrum analyzer with the azimuth movement and lock the movement.
In a similar manner move the elevation through a few degrees to peak the signal. Lock the movement.
Rotate the LNB horn assembly to peak the signal in polarization. Once again, lock the movement.
Repeat all the above to ensure that the signal is fully peaked. Lock all movements making sure that
the locking off does not cause further movement.
If no signal is found during the azimuth movement return the antenna to center and increase the
elevation by an amount equal to the beam width of the antenna. Repeat the swings in azimuth.
If there is still no signal, increase the elevation by another beam width and sweep the azimuth again.
Continue in this manner until the elevation has been increase by 2 to 3 degrees.
If there is still no signal, lower the elevation from nominal and make the swings in azimuth. Ensure
that the azimuth moves are made very slowly otherwise the signal may be missed.
If the signal cannot be found check the calculations and the coarse pointing procedure before
repeating the above.
NOTE: If the satellite concerned is supporting TV signals, alignment may be carried out using standard
signal strength measuring equipment designed for the satellite TV industry. Substitute a standard
TVRO LNB and follow the above procedure whilst watching the signal strength meter. Once the
antenna is pointed in this way, refit the system LNB.
Alignment can be rechecked once the receiver has acquired the correct signal by using E
b
/N
o
readings
from the receiver and by monitoring the signal quality indicator on the front of the receiver.
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