Sea Tel 9711QOR-86 Installation And Operation Manual Download

Page: 107 / 243

9711QOR-86 C & Ku-Band TXRX

Setup – Optimizing Polarity & Cross-Pol Isolation

14-1

14.

Setup – Optimizing Polarity & Cross-Pol Isolation

The only way to optimize the polarization of the antenna properly is to peak the polarity angle while the system is in auto-

polarization mode. This automatically adjusts the polarization of the feed by calculating the required polarization angle for the

feed every 2 seconds based on ship's Latitude, Longitude and the desired Satellite Longitude.

14.1.

Polarity Angle (POLANG) Parameters

First of all make sure that the polang parameters are set correctly:

POL TYPE – should be set to 0074 when using the C-Band reflector (do not select Reflector “B”).

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).

POL SCALE – Leave this at the factory default setting of 0090.

Go to the TX POLARITY parameter in the Setup menu of the ACU and set this parameter to your assigned

Transmit polarity (1=LHCP, 2=Horizontal, 3=RHCP or 4=Vertical).

Target your desired satellite (as provided by you airtime provider).

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.

Allow tracking to peak the satellite signal.

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.

14.2.

Optimizing Auto-Polarization on Receive Signal

This procedure optimizes the linear polarization of the feed based on the received signal level.

Verify that tracking is ON and that the antenna is peaked on your targeted satellite (targeting calculates the

azimuth, elevation and polarization angles).

Go to the SAT SKEW parameter in the Satellite menu of the ACU. Default setting is 0000 and may be
incremented, or decremented, to adjust polarization while in Auto-Pol mode. Each increment equals one

degree of polarization rotation, decrement below 0000 for minus polarization.

Press the RIGHT arrow to edit the current value.

While watching the modems signal strength, the ACUs AGC value, or the spectrum analyzer satellite signal

level, press the UP arrow to increment or the DOWN arrow to decrement the value and then hit the ENTER

key to adjust the feed to the new value.

Allow 10 seconds between increments or decrements to allow time

for feed assembly to drive to new position.

Press the RIGHT key again, make another small change in the same direction and hit ENTER to carry out the

adjustment.

Repeat this process of making small adjustments in the same direction until you see the modem signal

strength, ACUs AGC value, or the spectrum analyzer satellite signal level decrease a noticeable amount (10

counts on the signal strength, 10 counts of AGC or ½ dB of signal level).

Note the SAT SKEW value.

Make a series of small changes in the opposite direction until you see the signal peak and then fall the same

amount as noted in step 6.

Note this SAT SKEW value.

10.

Set SAT SKEW to mid way between the value noted in step 7 & 9.

11.

Save your new SAT SKEW value.

14.3.

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).