ATTACHMENT A:
CASE STUDIES
Case study 1
To achieve acceptable reception quality a certain satellite signal requires an earth station G/T of 24 dBK. It is known that the LNC to be used has a noise temperature of 200K and the (clear sky) antenna temperature can be assumed to be 50K. The satellite signal operates at 12.5 GHz. For realistic range of dish efficiency values determine the range of dish sizes that will achieve the G/T requirement and comment on which is likely to be preferred.
Solution
Case study 2
It is desired to use Optus satellites at 156 and 160 degrees to transmit different services to an earth station in Canberra . Does a 0.7 m antenna have enough discrimination to receive the signals without interference? Perform the calculations for 1.5 GHz, 12.5 GHz and 30 GHz. Assume both satellites produce equal EIRP levels at the Canberra receiving site.
Solution
Case Study 3
For a 4.5m earth station operating at 12.5 GHz calculate the loss of potential gain if the satellite is 0.125 degrees north and 0.1 degrees east of its nominal position. Assume the dish is pointed precisely at the nominal satellite position.
Solution
Case Study 4
Calculate the effect on system noise temperature of the satellite receivers noise temperature given the following data.
Solution
Case Study 5
Using the antenna and LNC cost data in sections 2 and 5 specify the least cost dish size/LNC noise figure combination needed to achieve a clear sky G/T of 24 dBK. (Perform the calculations for a Ku band system).
Solution
Case study 6
Determine the (clear sky) atmospheric attenuation to be expected for the following satellite signals at a reception site in Canberra. Assume a notional satellite position of 160oEast.
Solution
Case study 7
Calculate the 0.5% and 0.1% worst month rainfall attenuation for 12.75 GHz at Canberra (1% W.M. rain fall is 3mm/hr and 0.1% W.M. rain fall is 12 mm/hr).
Solution
Case study 8
Repeat Case study 5 for 1% and 0.1% of worst month rainfall case in Canberra.
Solution
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