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Setup
5.1.
Sat Skew setting
The Satellite Skew setting in the Satellite – Tracking Receiver sub-menu (prior to NID) is used to enter the skew of the
satellite to optimize polarity angle.
This feature will replace the use of POL OFFSET to optimize polarization of the feed. From here on out, POL OFFSET
will serve to calibrate the feed itself. Think of it as mechanical calibration. We will recommend that you target a
satellite that is of your same longitudinal position (ie for us here in Concord we would target 122W). Drive the
reflector to 0 or 5 degrees elevation (this is so you can easily view the feed). Drive the feed to vertical and then place
a level bubble on the LNB. Add or subtract POL OFFSET as required to center the air bubble. Then save this parameter.
Cross-pol isolation tests will now require the operator to increase or decrease the SAT SKEW parameter. Each digit
represented on this screen represents one whole degree of feed drive. This parameter addition was a direct response
to item #3 below which is making the ACU's work with Satellite Modems that are OpenAMIP compatible.
5.2.
Polarity Angle (POLANG) Parameters
First of all make sure that the polang parameters are set correctly:
1.
POL TYPE – should be set to 0072 (Auto-Pol mode).
2.
POL OFFSET – This is initially set to factory default (0040) but will be incremented, or decremented, to
calibrate the feed to the horizon with a level (bubble or digital).
3.
POL SCALE – Leave this at the factory default setting of 0090.
4.
Go to the TX POLARITY parameter in the Setup menu of the ACU and set this parameter to your assigned
Transmit polarity (2=Horizontal or 4=Vertical).
5. Target your desired satellite (as provided by you airtime provider).
6. Verify the system has acquired the correct satellite, else continue searching until the correct satellite is
acquired, and set your satellite modem (or spectrum analyzer) to view its signal level display.
7. Allow tracking to peak the satellite signal.
8.
SAT SKEW – This setting will be incremented, or decremented, to optimize the polarity to peak the received
satellite signal, and later to do cross-pol isolation with the airtime provider, network operation center or
satellite provider.
5.3.
Optimizing Auto-Polarization Cross-Pol Isolation
During commissioning, under guidance from the network operation center, you will be adjusting to minimize the effect
of your transmission on the opposite polarization which maximizes your Cross-Pol isolation. Contact your satellite
provider to help you (over the phone) to optimize the polarity angle for maximum Cross-Pol isolation (this optimizes
your transmit polarity and is much more accurate than trying to optimize your receive polarity).
1.
Verify that tracking is ON and that the antenna is peaked on your targeted satellite (targeting calculates the
azimuth, elevation and polarization angles).
2.
Follow your service provider technicians instructions to set the modem to begin transmitting a CW (pure
carrier) signal.
3.
Go to the SAT SKEW parameter in the Satellite menu of the ACU.
4.
Press the LEFT arrow to edit the current value.
5.
While under direction of the technician (on the phone), press the UP arrow to increment or the DOWN arrow
to decrement the value and then hit the ENTER key to adjust the feed.
6.
The technician should indicate whether the adjustment you made improved, or worsened, the cross-pol
isolation. If it improved he will have you make another small adjustment in the same direction. If it
worsened he will have you make a small adjustment in the opposite direction.
7.
Press the RIGHT key again, make the next change as directed and hit ENTER to carry out the adjustment.
8.
Repeat this process of making small adjustments until the technician confirms that cross-pol isolation is
optimized.
9.
Save your new SAT SKEW value.
5.4.
Calibrating Relative Antenna Position (Home Flag Offset)
During initialization, azimuth drives the CW antenna until the Home Switch is contacted, which "presets" the relative
position counter to the value stored in the Home Flag Offset. This assures that the encoder input
increments/decrements from this initialization value so that the encoder does not have to be precision aligned.
9497B-1 C/Ku-Band TVRO
5-2
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Table of Contents
Troubleshooting
