Archive for the ‘Free to Air’ Category
A Low Noise Block (LNB), which is also known as a Low Noise Converter (LNC), is primarily used in communication satellite reception. You can usually find a LNB attached to the side of a satellite dish or located inside a dish. The sole purpose for using a LNB is to make the most of the super heterodyne effect, which is a principle used by practically every modern radio and television receiver broadcasting on air. Heterodyning, or frequency mixing, operates through the use of a super heterodyne receiver. This process is said to provide a balance for the signal loss associated with your typical coaxial cable at relatively high frequencies.
The familiar term low noise is associated with the quality of the first stage input amplifier transistor, which is measured by the Noise Temperature units, Noise Figure units or Noise Factor units. Noise factor and noise figure are actually the same units, they are what creates the amount by which the signal-to-noise ratio is degraded. These two units are converted into Noise Temperature units. One should strive to obtain a low Noise Temperature rating because it is the best.
The term block, when associated with LNB’s, refers to the conversion of a higher block of microwave frequencies, usually received from the satellite itself and typically in the range of 4 to 21 GHz, being down-converted to a lower block range of frequencies for the FTA receiver. High frequencies are very necessary for satellites to function according to their highest capacity. This is the only way to ensure that noise is controlled before the signaling process. One of the major purposes for using an LNB is to provide a medium for quality sound and picture from satellite TV; if not, then you risk the chance of degradation. Using a LNB eliminates the need of a much larger dish reflector.
There are different types of LNB’s to choose from depending upon the need. The most commonly used LNB’s are Universal LNB’s and Quad Universal LNB’s. The universal LNB’s can receive both polarizations and the full range of frequencies in both the Ku and C satellite band. Some LNB’s can receive both polarizations simultaneously, through 2 different connectors, while other LNB’s have either switchable or adjustable polarizations.
The Quad Universal LNB can accommodate four separate receivers and each receiver has independent control of band and polarization via 13v, 17v and 22kHz on and off switching respectively. This particular LNB is primarily designed to deploy in the Sky Digibox, which is a device marketed by British Sky Broadcasting in the UK and Republic of Ireland to enable home users to receive digital satellite television broadcasts from the Astra satellite at 28.2 degrees east.
There’s even an internet service made available through the device that operates similar to MSN TV. There’s also the OCTO LNB, which is no different than the Quad; however, it has 8 independent outputs while the Quad only has four. For a list of the typical Universal LNB specifications, visit one of the many internet sites online.
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