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Satellite internet service in Africa Satellite broadband: how it works Out link budget calculation W3A |
Satellite internet service for southern Africa ViaSat LinkStar
The LinkStar broadband satellite internet access hub is in Turin, located within the coverage patterns shown in the left pair of images.
Service started 20th Oct 2004
W3A Frequency bands are:
Africa: down 10.95 - 11.2 GHz and 12.5 - 12.75 GHz, Africa up:
14.0 - 14.5 GHz
Europe: down 10.95 - 11.2 GHz and 12.5 - 12.75 GHz, Europe up: 14.0 - 14.5
GHz
Transponders are cross-strapped so that signals going up in the Africa beam come
down in the Europe beam and vice-versa.
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| For the W3A hub end of the link budget calculations use downlink eirp and uplink G/T figures from the two coverage maps below. | |
For the W3A African end of the link budgets use the downlink eirp and uplink G/T figures from the contours in the map above
Depending on location, 1.2m or 1.8m diameter dishes are required to receive a satisfactory out-link signal from W3A. Use of the smallest possible dish size to achieve a service that just works well in clear sky conditions (e.g. 98 cm) will always result in outages during significant rain. Use of dishes with approximately twice the area will give a 2dB margin for rain fading and provide a satisfactory service in many cases. Larger dishes result in shorter outages during rain storms.
The return link (transmit) bit rate required is also a factor affecting the dish sizes required. If you need a very high return link (transmit) bit rate it may be better to use a larger dish rather than a higher power transmitter.
The Eutelsat W3A satellite was launched 16th March 2004, to orbit location at 7 deg east.
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20 Oct 2004: W3A LinkStar Africa beam service started. |