Step 6
Step 7
Step 8
Step 9
Move the antenna in elevation while observing the spectrum analyzer screen. If the sig- nal amplitude increases, decreases and then increases again but to a lesser value, the antenna is moving in the wrong direction; reverse the direction of the antenna move- ment. From the original null point, the signal level should decrease and increase alter- nately, but with an increasing amplitude until the transponder signal increases to a level of at least 30 dB. Continue to manually peak the signal to a maximum level using the azimuth and elevation adjustments.
If the antenna is aligned in azimuth and elevation (signal maximized) and 24 transpon- der signals (12 horizontal and 12 vertical) are noted, the polarization adjustment is set incorrectly and must be modified. If 12 transponder signals are noted, they may or may not be the properly polarized signals. Therefore 24 transponder signals must be visually noted in order to determine the proper polarization setting.
Rotate the feed assembly clockwise until 24 transponder signals are noted and of approximately equal amplitude. Note: It is more accurate and visually easier to minimize the alternate set of transponder signals rather than maximizing the transponder of inter- est.
Figure 4
With all 24 transponder signals of approximately equal amplitude appearing on the spectrum analyzer screen determine the specific antenna system and satellite parame- ters. Rotate the feed assembly as required until the appropriate (odd or even) transpon- der signals are maximized.
71 | Operation |