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SeaTel antenna Cross pole issue

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Ex Member
Ex Member


Mar 22nd, 2010 at 12:23pm  
Hi,

Has anybody had any issue with doing cross pole test for the Seatel Antenna . Please share your experience and what you did to over come this.

Regards
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Ex Member
Ex Member


Reply #1 - Mar 24th, 2010 at 6:44am  
you should be able to bring up a CW carrier with the satellite POC and from the adjust the polarization offset through the DAC controller. They will be able to monitor the isolation between pol's.

If receive only conenct up your spec an and simply adjust the pol offset in the DAC untill it is peaked.

Is this TxRx or Rx only?
Cheers,
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Ex Member
Ex Member


Reply #2 - Apr 29th, 2010 at 12:15pm  
If your antenna is well balanced I would recommend the following. 
-  Disable tracking
-  Manually peak az/el and call operator to commission. 

I have seen at times with tracking on the carrier fluctuate 1-3db and just enough where the operator will not pass because of this fluctuation.  Never hurts to call back and ask for another operator as well.
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Ex Member
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Reply #3 - Oct 17th, 2010 at 4:11pm  
When you call up the satellite provider for a croos-pol check on a stablised antenna you must tell them it is a stablised terminal. Because stablised antennas have different tolerances with their cross-pol than fixed dishes.

FYI.... Most stablised antenna track within .5dB. Anything greater than that, check your balance and antenna controller configuration. Hope this helps and goodluck!!!

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Ex Member
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Reply #4 - May 29th, 2011 at 7:14am  
Hello all,

I just tried to commision a site and i was told i am transmitting @ both poles. can anyone help me with the right configuration of my polariser.

I neet to transmit LHCP and Receive Right

My Antenna is ChannelMaster 2.4m with Circular Polariser
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Eric Johnston
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Reply #5 - May 29th, 2011 at 8:35am  
If you are transmitting approx equal levels into both circular polarisations at the satellite it is likely that you are transmitting linear polarisation. This may happen if you have linear feed system (just OMT to the horn) without a polariser or have a polariser but have installed the polariser incorrectly.

If you have a polariser (long tube, square or circular with two rows of pins or slots inside) you have it with the pins/slots lined up the same as the linear polarisations of the OMT. That is wrong.

The lines of pins/slots must be at 45 deg relative to the OMT TX/RX waveguides.  Do that.

Now you will transmit all power on one circular polarisation. If you are now correct your receive performance will improve by at least 3 dB.  If you are wrong you won't get any of your wanted receive signal at all.  If you are on wrong polarisation undo the big circular flange and turn the OMT 90 deg, so it is 45 deg the other way. Check with the hub when you are ready to transmit.

Read more and see images here:
http://www.satsig.net/pointing/circular-polarisation-set-up.htm
wxw
Best regards, Eric
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« Last Edit: May 29th, 2011 at 1:11pm by Admin1 »  
 
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