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Block upconverter
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<p>A block upconverter (BUC) is a component used in the <a href="/facts/Transmission_(telecommunications)/33zk8a0A">transmission</a> (<a href="/facts/Uplink/wCxVKCKo">uplink</a>) of <a href="/facts/Satellite/PTX8c68t">satellite</a> signals. It converts a band of <a href="/facts/Frequencies/QUSbPaW8">frequencies</a> from a lower frequency to a higher frequency. Modern BUCs convert from the <a href="/facts/L_band/6l9P26IP">L band</a> to <a href="/facts/Ku_band/czTuuqpT">Ku band</a>, <a href="/facts/C_band_(IEEE)/vLddLTc2">C band</a> and <a href="/facts/Ka_band/YqDrokxy">Ka band</a>. Older BUCs convert from a 70 <a href="/facts/Megahertz/6Wshj5qm">MHz</a> intermediate frequency (IF) to Ku band or C band. </p><p>Most BUCs use <a href="/facts/Phase-locked_loop/sgmca8aQ">phase-locked loop</a> local <a href="/facts/Electronic_oscillator/6NaXsSzJ">oscillators</a> and require an external 10 MHz <a href="/facts/Frequency_reference/VrTvqGam">frequency reference</a> to maintain the correct transmit frequency. </p><p>BUCs used in remote locations are often 2 or 4 <a href="/facts/Watt/VK8oqRrm">W</a> in the <a href="/facts/Ku_band/czTuuqpT">Ku band</a> and 5 W in the C band. The 10 MHz reference frequency is usually sent on the same feedline as the main <a href="/facts/Carrier_wave/ae98pBlY">carrier</a>. Many smaller BUCs also get their <a href="/facts/Direct_current/r9MNUx84">direct current</a> (DC) over the feedline, using an internal DC block. </p><p>BUCs are generally used in conjunction with <a href="/facts/Low-noise_block_converter/4CNPNzMb">low-noise block converters</a> (LNB). The BUC, being an up-converting device, makes up the "transmit" side of the system, while the LNB is the down-converting device and makes up the "receive" side. An example of a system utilizing both a BUC and an LNB is a <a href="/facts/Very_small_aperture_terminal/L4HjYjAu">VSAT</a> system, used for <a href="/facts/Duplex_(telecommunications)/LCULeVxr">bidirectional</a> <a href="/facts/Internet/Xw1rVvJU">Internet</a> access via satellite. </p><p>The block upconverter is a block shaped device assembled with the LNB in association with an OMT, <a href="/facts/Orthomode_transducer/5vTQX7JC">orthogonal mode transducer</a> to the feed-horn that faces the reflector parabolic dish. This is opposed to other types of frequency upconverter which may be rack mounted indoors or not co-located with the dish. </p>