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https://www.satsig.net/cgi-bin/yabb/YaBB.pl VSAT technology and installation >> Dish pointing and alignment >> LO frequency mismatch https://www.satsig.net/cgi-bin/yabb/YaBB.pl?num=1141381586 Message started by erskine2020 on Mar 3^rd, 2006 at 10:26am

Title: LO frequency mismatch
Post by erskine2020 on Mar 3^rd, 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: erskine2020@yahoo.com

regards:-

erskine voon

Title: Re: LO frequency mismatch
Post by USN - Retired on Mar 3^rd, 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.

//greg//

Title: Re: LO frequency mismatch
Post by Eric Johnston on Mar 3^rd, 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.