DirecTV LNB

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To make you more clear, please allow me to explain in a bit details :)

Satellites use high radio frequencies to transmit their signals and it is hardly to pass through walls, roofs, or even glass windows. Therefore, the direct tv dish is set at the outdoor, mostly on roof top. ( Better still, set the dish in the open space that not block by any tall building in all directions )

The Satellite signal needs to be passed indoors via cables. When radio signals are sent through coaxial cables - the higher the frequency, the more losses occur in the cable per unit of length.

The signals used for satellite are of such high frequency (in the multiple gigahertz range) that expensive cable types or waveguides would be required and any significant length of cable leaves very little signal left on the receiving end.

The major function of a DirecTV LNB is to use the superheterodyne principle to take a wide block (or band) of relatively high frequencies, amplify and convert them to similar signals carried at a much lower frequency (called intermediate frequency or IF).

These lower frequencies travel through cables with much less attenuation of the signal, so there is much more signal left on the Direct TV receiver end of the cable.

It is also much easier and cheaper to design electronic circuits to operate at these lower frequencies, rather than the very high frequencies of satellite transmission.

The low-noise part means that special electronic engineering techniques are used, that the amplification and mixing takes place before cable attenuation and that the block is free of additional electronics like a power supply or a digital receiver.

This all leads to a signal which has less noise (unwanted signals) on the output than would be possible with less stringent engineering.

In overall, higher the frequencies with which an electronic component has to operate, the more critical it is that noise be controlled.

If low-noise engineering techniques were not used, the sound and picture of Direct TV would be of very low quality, if it could even be received at all without a much larger dish reflector.

The low-noise quality of an LNB is expressed as the noise figure or noise temperature. For the reception of wideband satellite television carriers, typically 27 MHz wide, the accuracy of the frequency of the LNB local oscillator need only be in the order of ±500 kHz, so low cost dielectric oscillators (DRO) may be used.

For the reception of narrow bandwidth carriers or ones using advanced modulation techniques, such as 16-QAM, highly stable and low phase noise LNB local oscillators are required.

Check out also the Verizon Direct TV Tips instead of DirecTV LNB

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