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Satellite Systems - What to Buy - What to install
Symbol Rate. ?
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<blockquote data-quote="tesla" data-source="post: 429055" data-attributes="member: 218346"><p>Symbol rate depends on the bandwidth used. In DVB-S transmissions (that use QPSK) one symbol means 2 bits.</p><p>So, (bit rate)=(symbol rate)*2. This is the total bit rate. The useful bit rate (used for the services and the SI tables) is less than the total bit rate. The rest is the error correction data.</p><p>(total bit rate)=(useful bit rate)+(error correction bit rate)</p><p></p><p></p><p>SCPC carriers are used for fixed satellite services. One broadcaster can send material to another using an SCPC transmission. The commercial transmissions are MCPC.</p><p></p><p>In the past, some receivers were incapable of receiving low bit rate signals. Some old receivers could support 16-45MSps (for example).</p><p></p><p>If the carrier has a low symbol rate (not 27500 or 30000 but 4123, 3666 etc) then the total bandwidth of the carrier is also low. If the Local Oscillator of the LNB is not accurate then it may be difficult to receive. You may have to "play" with the frequency (increase or decrease it). I have faced a problem like this. Although i had a professional LNB, i had to set the frequency to a higher value (+5MHz).</p></blockquote><p></p>
[QUOTE="tesla, post: 429055, member: 218346"] Symbol rate depends on the bandwidth used. In DVB-S transmissions (that use QPSK) one symbol means 2 bits. So, (bit rate)=(symbol rate)*2. This is the total bit rate. The useful bit rate (used for the services and the SI tables) is less than the total bit rate. The rest is the error correction data. (total bit rate)=(useful bit rate)+(error correction bit rate) SCPC carriers are used for fixed satellite services. One broadcaster can send material to another using an SCPC transmission. The commercial transmissions are MCPC. In the past, some receivers were incapable of receiving low bit rate signals. Some old receivers could support 16-45MSps (for example). If the carrier has a low symbol rate (not 27500 or 30000 but 4123, 3666 etc) then the total bandwidth of the carrier is also low. If the Local Oscillator of the LNB is not accurate then it may be difficult to receive. You may have to "play" with the frequency (increase or decrease it). I have faced a problem like this. Although i had a professional LNB, i had to set the frequency to a higher value (+5MHz). [/QUOTE]
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Satellite Systems - What to Buy - What to install
Symbol Rate. ?
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