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Satellite TV receivers & systems support forums
Satellite Systems - What to Buy - What to install
Dish Size for DVB-S / DVB-S2 / DVB-S2X
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<blockquote data-quote="esto" data-source="post: 892230" data-attributes="member: 368402"><p>Thanks, yes I check SATbeams, but they just give dish size recommendations based on the beam, not the specific transponder (which may have different modulation rates). </p><p></p><p>The RSL (Recieve Signal Level) is fixed between the sat and the dish, but for higher order modulation (eg. 16-PSK, 64-PSK, etc.) you will need a stronger signal to decode it in poor weather compared to lower order modulation like QPSK.</p><p></p><p>In LOS microwaves, they have Adaptive Modulation, meaning when the weather is good, it uses the highest modulation available (256-QAM in this case)to have maximum bandwidth, but when weather gets bad, then it drops to lower modulation (4-QAM in this case), because it can be decoded easier, but then the bandwidth drops. See attached pic:</p><p></p><p></p><p><img src="http://id.nec.com/en_ID/files/images/AMR_0.png" alt="" class="fr-fic fr-dii fr-draggable " style="" /> </p><p></p><p>The same basic principal applies to satellites as well. Right now DVB-S uses QPSK (4-PSK). DVB-S2 uses 8-PSK, so it requires a stronger signal to be decoded when bad weather or obsticals are present, compared to DVB-S which uses 4-PSK. If DVB-S2X will use something like 16 or 64 QAM, then alot of people are going to need to upgrade dish size to decode this modulation, because of it's sensitivity.</p></blockquote><p></p>
[QUOTE="esto, post: 892230, member: 368402"] Thanks, yes I check SATbeams, but they just give dish size recommendations based on the beam, not the specific transponder (which may have different modulation rates). The RSL (Recieve Signal Level) is fixed between the sat and the dish, but for higher order modulation (eg. 16-PSK, 64-PSK, etc.) you will need a stronger signal to decode it in poor weather compared to lower order modulation like QPSK. In LOS microwaves, they have Adaptive Modulation, meaning when the weather is good, it uses the highest modulation available (256-QAM in this case)to have maximum bandwidth, but when weather gets bad, then it drops to lower modulation (4-QAM in this case), because it can be decoded easier, but then the bandwidth drops. See attached pic: [IMG]http://id.nec.com/en_ID/files/images/AMR_0.png[/IMG] The same basic principal applies to satellites as well. Right now DVB-S uses QPSK (4-PSK). DVB-S2 uses 8-PSK, so it requires a stronger signal to be decoded when bad weather or obsticals are present, compared to DVB-S which uses 4-PSK. If DVB-S2X will use something like 16 or 64 QAM, then alot of people are going to need to upgrade dish size to decode this modulation, because of it's sensitivity. [/QUOTE]
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Satellite TV receivers & systems support forums
Satellite Systems - What to Buy - What to install
Dish Size for DVB-S / DVB-S2 / DVB-S2X
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