2010-10-26 Network Design and Engineering Guide 89Outdoor Unit and Satellite Link DesignSkyWAN® Link Budget Calculation ToolStep (3) For each network up to 20 earth station parameter sets may be defined:- “Location”: Each earth station is identified by a unique location name. The firstcolumn is reserved for one master station, because the home channel of this sta-tion is fixed to carrier 1. For star networks, the first two columns represent the net-work’s hub stations, the remaining stations are considered the remote terminalsof the network.Figure 3-15 Link Budget Tool - Define Network- ITU-T ’Rain Zone’.- ’Longitude’ and’“Lattitude’: Geographical coordinates (positive values meansnorthern/eastern hemisphere).- ’Uplink/Downlink Pattern disadvantage’: To be taken from the satellite footprint di-agram. Stations in the beam center have a disadvantage of 0 dB, for other sta-tions the difference between maximum and actual G/T or EIRP has to be entered.- ’Antenna’: type according to the defined frequency band of the network the pull-down menu allows the selection of any antenna type defined in the Ku- or C-Bandantenna sheet before.- ’Output Backoff’: The difference between saturation power and maximum usableoutput power of the station’s amplifier.- ’Number of IDUs at location’: the number of IDUs which are connected to the sta-tion’s ODU.- ’Altitude’ of geographical station position.- ’SkyWAN® Receive Home Channel’: The carrier used for reception on the prima-ry demodulator.Output Back-OffThe output back-off is needed to prevent intermodulation created by operating the amplifier tooclose to the saturation level. The necessary back-off is higher when more than one carrier istransmitted at the same time. In the case of SkyWAN® stations this is only possible if multipleIDUs are connected to the same amplifier. In this case recommended values for output back-
