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Fringe Reception General
Viasat on Sirius 2/3 Nordic Beam
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<blockquote data-quote="IanW" data-source="post: 375894" data-attributes="member: 176464"><p>Hi Flexi,</p><p></p><p>OK, I have the scuttlebuck.</p><p></p><p>Officially, Sirius-3 Vertical you're on the 31dBW contour, and Horizontal 34dBW-ish (I'm extrapolating between the 31 and 36 dBW countours). If you bang the numbers into this truly excellent Link Budget Calculator;</p><p></p><p>http://www.satellite-calculations.com/Satellite/Downlink.htm</p><p></p><p>Assuming a hopeful 60% efficiency for that petalised dish, a 0.2dB LNB, 35K noise figure for the dish which is a bit optimistic that the feedhorn is optimal. Gives you a 'WIN' of about 2dB above threshold for the Horizontal transponders provided it's a lovely Sunny blue-sky Jersey day (like in the brochure<img src="https://www.satellites.co.uk/styles/default/xenforo/smilies/smile.png" class="smilie" loading="lazy" alt=":)" title="Smile :)" data-shortname=":)" /> ) and the wind is behind you. For the Verticals you are on the ragged edge or in truth below.</p><p></p><p>Now a nice 2.4m spun dish or better still a 2.4 Gregorian offset and you'd be alright except for heavy rain events.</p><p></p><p>It is worth mentioning that this far off the main lobe of the beam means that there will be variations in the pointing as the satellite moves within it's permitted attitude control limits over a 23hr / 8 day / 3 week cycle. </p><p></p><p>If I recall correctly, the SSA (Swedish Space Agency) guys have a very funky active pointing system on their transmit antenna, both of their own design, so the maintenance of the beam pointing should be pretty good.</p><p></p><p>Let us know how you get on.</p><p></p><p>IanW.</p></blockquote><p></p>
[QUOTE="IanW, post: 375894, member: 176464"] Hi Flexi, OK, I have the scuttlebuck. Officially, Sirius-3 Vertical you're on the 31dBW contour, and Horizontal 34dBW-ish (I'm extrapolating between the 31 and 36 dBW countours). If you bang the numbers into this truly excellent Link Budget Calculator; http://www.satellite-calculations.com/Satellite/Downlink.htm Assuming a hopeful 60% efficiency for that petalised dish, a 0.2dB LNB, 35K noise figure for the dish which is a bit optimistic that the feedhorn is optimal. Gives you a 'WIN' of about 2dB above threshold for the Horizontal transponders provided it's a lovely Sunny blue-sky Jersey day (like in the brochure:) ) and the wind is behind you. For the Verticals you are on the ragged edge or in truth below. Now a nice 2.4m spun dish or better still a 2.4 Gregorian offset and you'd be alright except for heavy rain events. It is worth mentioning that this far off the main lobe of the beam means that there will be variations in the pointing as the satellite moves within it's permitted attitude control limits over a 23hr / 8 day / 3 week cycle. If I recall correctly, the SSA (Swedish Space Agency) guys have a very funky active pointing system on their transmit antenna, both of their own design, so the maintenance of the beam pointing should be pretty good. Let us know how you get on. IanW. [/QUOTE]
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Fringe Reception General
Viasat on Sirius 2/3 Nordic Beam
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