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Sky Digital BSkyB, Freesat & Saorsat support forum
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Signal levels of Sky in Spain
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<blockquote data-quote="Channel Hopper" data-source="post: 10943" data-attributes="member: 175144"><p>An evening of peering through the bottom of a number of ale bottles (why do they make them hold so little !) has come up with the following </p><p>(pay attention at the back - I shall say this only once )</p><p></p><p>Taking the difference of apogee v perigee as a possibility of altering fringe power levels to an extent where they are noticed by a ground observer, I have assumed the satellite is controllable to a limit of 80kms. On a satellite such as Astra 2B, running it through the abacus on a footprint of diameter 1600kms means a variation in edge of similar signal of about 45kms, and a difference in area of signal just under 97% of it at perigee.</p><p></p><p>As one can see from the published footprint for Astra 2B </p><p><a href="http://www.ses-astra.com/satellites/footprints_new.php?value=4&sat=13" target="_blank">http://www.ses-astra.com/satellites/footprints_new.php?value=4&sat=13</a></p><p></p><p></p><p>there is an area of signal that covers Spain and so the fall off in signal, (and therefore dish size ) can be taken as factual reports from Astra and backed up elsewhere in this forum.</p><p></p><p>Since the fall off is quite dramatic on the footprint above, it is logical to assume that locations further away experience an equal or greater slope of signal to the publicised figures. For arguments sake I will take it as equal which would be the more optomistic but less argumentative case.</p><p></p><p>The footprint map shows different illuminated areas relating to different dish sizes of 50, 60, 75, 90, 1.2 and so on. These last two are good to highlight as there is an approximate increase in receiving capability of 100% between them(an increase of twice the diameter leads to approximately 4 times the gain).</p><p></p><p>On the part that shows Spain an approximate distance drawn between the innermost and outermost contour (ie 50cms to 1.2m or 5.6 times the power receivable) is 400kms</p><p></p><p>Again from the map it is reasonable to assume the signal area contracted by approximately 45 kms lowers the signal at the outer edge (using the above paragraph figures) to a little under half as a direct result of the satellite movement as orbital height difference.</p><p></p><p>I can conclude therefore that this movement will have a dramatic effect on fringe viewing of this group of satellites (and may go someway of explaining why the Sirius Group at 5E is such a bugger for people to receive in the UK when South of Watford) </p><p></p><p>More interesting is that the centre of any footprint will actually notice a 3% increase in signal when reaching perigee as the area of footprint is more concentrated at this point, but thats another story.</p><p></p><p>I thank you.</p></blockquote><p></p>
[QUOTE="Channel Hopper, post: 10943, member: 175144"] An evening of peering through the bottom of a number of ale bottles (why do they make them hold so little !) has come up with the following (pay attention at the back - I shall say this only once ) Taking the difference of apogee v perigee as a possibility of altering fringe power levels to an extent where they are noticed by a ground observer, I have assumed the satellite is controllable to a limit of 80kms. On a satellite such as Astra 2B, running it through the abacus on a footprint of diameter 1600kms means a variation in edge of similar signal of about 45kms, and a difference in area of signal just under 97% of it at perigee. As one can see from the published footprint for Astra 2B [url]http://www.ses-astra.com/satellites/footprints_new.php?value=4&sat=13[/url] there is an area of signal that covers Spain and so the fall off in signal, (and therefore dish size ) can be taken as factual reports from Astra and backed up elsewhere in this forum. Since the fall off is quite dramatic on the footprint above, it is logical to assume that locations further away experience an equal or greater slope of signal to the publicised figures. For arguments sake I will take it as equal which would be the more optomistic but less argumentative case. The footprint map shows different illuminated areas relating to different dish sizes of 50, 60, 75, 90, 1.2 and so on. These last two are good to highlight as there is an approximate increase in receiving capability of 100% between them(an increase of twice the diameter leads to approximately 4 times the gain). On the part that shows Spain an approximate distance drawn between the innermost and outermost contour (ie 50cms to 1.2m or 5.6 times the power receivable) is 400kms Again from the map it is reasonable to assume the signal area contracted by approximately 45 kms lowers the signal at the outer edge (using the above paragraph figures) to a little under half as a direct result of the satellite movement as orbital height difference. I can conclude therefore that this movement will have a dramatic effect on fringe viewing of this group of satellites (and may go someway of explaining why the Sirius Group at 5E is such a bugger for people to receive in the UK when South of Watford) More interesting is that the centre of any footprint will actually notice a 3% increase in signal when reaching perigee as the area of footprint is more concentrated at this point, but thats another story. I thank you. [/QUOTE]
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Signal levels of Sky in Spain
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