Regarding Cross Polarisation Test

[jethooo]

I'm a newbie in Satellite communications so please help me out in this matter.

My query is why do we need to do Cross Polarisation Test before transmitting the modulated carrier and why do we transmit pure carrier for that?

Any kind of help will be appreciated.

[wejones]

Originally Posted by jethooo

I'm a newbie in Satellite communications so please help me out in this matter.

My query is why do we need to do Cross Polarisation Test before transmitting the modulated carrier and why do we transmit pure carrier for that?

Any kind of help will be appreciated.

I don't think there are any uplinkers here on this forum. You'd be better off asking this question over at satforums, where there ARE some uplinkers.

However I would assume, that if you are transmitting, the number one priority is to not interfere with any other signal, and proper polarity is essential for that, and if the polarity is off, a pure carrier is less likely to interfere than a modulated signal.

But again, you're better off talking to someone who actually uplinks.

ALTHOUGH, with the increasing popularity of these satellite internet setups, more and more people are becoming uplinkers, and I'm really amazed that the FCC has let this happen, as it seems to be asking for trouble. I have to wonder if PBS has interferrence problems with their 12180 PBS signal on AMC3 due to thousands of poorly aimed low resolution Hughesnet dishes aimed at G28.

[MrBillM]

Back when Dish Network first began offering two-way Satellite Internet (Gilat- Later Starband), I became acquainted with a "Computer Illiterate" Dish dealer who need help setting up the system supplied to him by Dish Network. Subsequent to that, I assisted him on numerous installations.

Because many Dish Network dealers had gotten used to "roughing in" their alignments, the same carried over into the Internet installs. After awhile, the dealer received notice from Dish that they were suspending ALL such installations until every authorized dealer could pass a required installation qualification test. They enclosed copies of notices that they'd received from the FCC that many of the intallations were interfering with neighboring commercial satellites. The FCC was threatening to stop Dish from offering any further installs unless they corrected the problems.

Given the fact that many users are moving their antenna systems after the original install, especially those bringing units to Baja from the U.S., I am surprised that there aren't many such complaints. For most people, the usual course is to get a useable signal and call it good.

Since I'm no longer involved (except as a Hughes Net user), I don't get any of that "inside" info any longer so, perhaps, it is still a problem.