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iDirect LNB 11300 to 10000 Option File

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Ex Member
Ex Member


Sep 1st, 2007 at 11:53am  
Hi all,
I am installing an iDirect modem, and the provider sent me an option file for LNB with LO Freq 11300. But my LNB has LO Freq 10000.

The old option file for LNB 11300 is
               rx_freq = 1346149999
     rx_acqrange = 3000000
     rx_bitrate = 4918000
     rx_mode = 2
     rx_modtype = 1
     rx_fecrate = 15
     rx_scram = 1

Could you please tell me the new rx_freq and other things that I have to modify on the above shown option file sothat it can work with LNB 10000.

Thanks;
Peter
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Eric Johnston
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Posts: 2109
Reply #1 - Sep 2nd, 2007 at 11:23am  
Your satellite downlink frequency may be calculated as follows:
    1,346,149,999  Hz (L band cable frequency)
+  11,300,000,000 Hz (LNB local oscillator frequency)
=  12,646,149,999 Hz
or 12.646149999 GHz

This 12.6 GHz frequency is in the upper part of the Ku band and you need an LNB with a local oscillator like 11.3 GHz to get the cable L band frequency down to within the design range of the iDirect modem receive input, which is, I believe, 950 - 1700 MHz.

If you consider the 10 GHz LO LNB.  The calculation would give an output frequency into the cable of 2.646 GHz and this is not acceptable to the iDirect modem.  The 10 GHz LNB will have been made for satellite downlink frequences like 10.95 - 11.7 or 10.95 - 12.15 GHz, so you are unlikely to see much LNB output at 2.646 GHz anyway.

Explain the situation to your service provider.  There is a possibility that they may have another iDirect hub service on a different satellite at a suitable frequency for your 10 GHz LNB.  Otherwise you will need to buy a Ku band LNB with 11.3 GHz local oscillator frequency.  

Read more about LNB local oscillator frequencies

Best regards, Eric.
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« Last Edit: Sep 4th, 2007 at 9:23am by Admin1 »  
 
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