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If you examine the satellite uplink coverage map you can determine the satellite uplink G/T for the contour line covering the uplink earth station site.
For example, at beam centre the uplink G/T might be +6 dBK. Let us assume our uplink site is on the -4 dB contour; the uplink G/T for us is then +2 dBK. Simply put the satellite uplink G/T, at the uplink site, (i.e. 2) into your link budget.
Typical beam edge satellite uplink G/T:
C band: Global -12 dBK, Hemi -9 dBK, Zone -7 dBK, Spot -5 dBK,
Ku band: Spot 0 to +4 dBK.
The number of dB down for the beam edge is a matter of opinion, it depends where you want to define the edge. Typically at about the -4/5 dB contour the beam is starting to drop off rapidly so there will be large variations in uplink G/T, the uplink sensitivity and downlink eirp as the satellite moves about slightly. The satellite attitude control points the antennas at the earth and it is difficult to maintain the pointing to an accuracy better than +/- 0.1 degrees.
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Return to the general purpose satellite link budget calculator with the figures deleted.
► Page amended 17 Oct 2016
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