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Step 2
Step 3
Step 4
Step 5
70
Operation
The maximum azimuth excursion from the original setting should not exceed ±1.5° or
the antenna may begin to access a different satellite.
With the antenna positioned in azimuth such that the transponder signals are maxi-
mized, follow the same procedure manually moving the antenna in elevation (scanning
up-and-down) to further maximize the transponder signals.
Repeat this procedure alternating between the azimuth and elevation excursions of the
antenna to peak the transponder signal amplitude.
A transponder signal amplitude of 30 dB or greater from peak to average noise signal
indicates the antenna is receiving the signal on the main beam. A transponder signal
amplitude less than 30 dB indicates the antenna is receiving the signal on the side lobe
of the main beam.
With the antenna peaked on a side lobe in azimuth and/or elevation, move the antenna
in azimuth while observing the spectrum analyzer screen as shown in Figure 3.
Figure 3
If the signal amplitude diminishes and does not increase (position B) to the level noted
when the antenna was peaked on the side lobe, the antenna is moving away from the
main beam; reverse the direction of the antenna movement.
From the original side lobe position (position A), the signal amplitude should now dimin-
ish to a null point at position C (minimum amplitude showing only signal noise) and then
symmetrically increase again to the same level at position D as noted at position A. At
the null point (position C), the antenna is aligned with the alternate (elevation) axis. If
the antenna was peaked on a side lobe in the azimuth, it was appropriately aligned with
the elevation axis; proceed with Step 6. If the antenna was peaked on a side lobe in ele-
vation, it was appropriately aligned with the azimuth axis; proceed with Step 6 moving
the antenna in azimuth rather than elevation.