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wrong satellite using a specified freq and symbol

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Ex Member
Ex Member

Oct 2nd, 2007 at 2:23pm  
Please Sir, how do I know wether am pointing to an almost indentical carrier on a wrong satellite using the same specified frequency and symbol rate and yet my modem BER is 0? If am pointing to another satellite then how will I bring it back to the specified satellite.Cos I have pushed the anntena off from the signal and repoint it still come to the same position to pick the signal.On this particular site the modem parameters as given by the NOC are well configured. but yet it is not locking to hub on that site.When taken the modem to another site at a different location it will lock.
what could be the possible solution the get this site online?
(urgent reply needed)
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Posts: 991
Reply #1 - Oct 2nd, 2007 at 9:06pm  
A BER=0 is unlikely unless the outlink carrier is unusually very high level or your dish exceptionally large.  A BER of about 0.00001234 should be expected for a LinkStar modem, and it should vary slightly each time you measure it.  If you slightly mispoint the dish the BER should increase.   A stuck zero value suggests an invalid readout to me.

If the same modem is moved about then it may need to be decommissioned and recommissioned at the new site with different lat-long coordinates before it will successfully transmit at the correct time.  Explain to the hub and seek their advice.  They need to put your site location into their database.

The LinkStar modem should give slow flashing green, then fast flashing green as it acquires the correct carrier.  Do tclgets, pcr should be true.

If you are on the wrong satellite, the next one will be in a line along the orbit.  From Nigeria the orbit is roughly east to west across the sky, via just south of directly overhead.

A 45 deg error in polarisation setting (for a linear polarisation system) will give you cross pol interference at the same level as the wanted signal, both at half level, so you may receive full total power but complete failure to lock.

Please post your messages once only, so people can concentrate all their effort to help you in one place. Thanks.

Best regards, Eric.
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Ex Member
Ex Member

Reply #2 - Oct 2nd, 2007 at 11:02pm  
LinkStar modems indeed can output zero, Eric and Edwin.

Zero QPSKBER means ideal antenna alignment. That's not a readout issue. Some of our customers have zero QPSKBER, on 1.2m antennas in the middle of a 50+ dBW EIRP spot.

Edwin, it's highly unlikely you have found a DVB carrier with the same frequency and symbol rate on a nearby satellite, however that is still possible.

By the way, you mention the inability to lock Rx or Tx? What is the status of the LEDs on the front of your unit?
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