An LNB, or Low Noise Block, is an amplifier which receives the radio signal from the satellite after it has been reflected by the satellite dish.
In addition to amplifying the signal, the LNB also converts the signal to a frequency usable by the In-Door-Unit.
The functions of the LNB were at one time provided by two separate components, a Low Noise Amplifier (LNA) for signal amplification and a block downconverter for downconversion.
Most LNB’s used for satellite television include an integrated feedhorn. An LNB with an integrated feedhorn is known an an LNBF.
All C-band LNB’s have a local oscillator (L.O.) frequency of 5.150 GHz but Ku-band LNB’s may come in many different frequencies, typically fro 9.750 to 12.75 GHz. This means that if you’re attempting to watch a Ku-band service you must set the decoder’s frequency using a bit of simple math. The formula to set the decoders frequency is the downlink frequency minus the local oscillator frequency.
The quality of C Band LNB’s are measured in degrees Kelvin, with a lower number representing a higher grade LNB. Ku and Ka band LNB’s are measured in decibels, with a lower number also representing a higher quality LNB.
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