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LO frequency mismatch

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Ex Member
Ex Member

Mar 3rd, 2006 at 10:26am  
hi all;

   i have a problem need all of you to give me an advice.
if the feedhorn LO frequency is not match with the LO frequency in satellite receiver, satellite receiver can receive the signal? how to overcome this problem? thanks...

if possible, send your feedback to my email account:


erskine voon
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USN - Retired
YaBB Moderator

Posts: 837
Kentucky (USA)
Reply #1 - Mar 3rd, 2006 at 1:46pm  
There may be a language issue here, but feedhorns are typically inert extensions of waveguide; no electronics, therefore no LOF. Their physical size is frequency-dependent though. The interior dimensions of waveguide passages are engineered for use with specifically identified frequency ranges.

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Eric Johnston
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Posts: 2109
Reply #2 - Mar 3rd, 2006 at 1:58pm  
LNBs have a variety of local oscillator (LO) frequencies.  In some cases the LO frequency may be switched by remote control from the indoor unit using a 22kHz tone on/off or by using two different DC supply voltages.

The indoor unit, if it is programmed with full satellite downlink frequencies (such as 12503 MHz) needs to know the LO frequency in the LNB so that the receiver can tune to the correct difference frequency in the L band cable, like 1203 MHz (in this case I assume a 11.3 GHz LO in the LNB.   12503 - 11300 = 1203MHz).

Best regards, Eric.
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