Technical Appendix46Technical AppendixSignal-to-noise distanceThe following values must be known in order to calculate the carrier-to-noise distance (C/N) for analogue transponders.• background noise level (set parabola antenna so that no satellitesignal is received)• max. receiving level• bandwidth correction.This gives the following formula:C/N = receiving signal level - background noise level - bandwidth correctionMeasured bandwidth of MSK 24 6 MHzBandwidth correction value = 10 log ——————————————–--------RF bandwidth of receiving signalBandwidth correction value = 6.37 dB at 26 MHz bandwidth (Astra)Bandwidth correction value = 7.78 dB at 36 MHz (Eutelsat, Intelsat, Kopernikus)ExampleReceiving signal level +75.5 dB with satellite signalBackground noise level -55.0 dB without satellite signalCarrier-to-noise distance C/N +20.5 dBBandwidth correction - 6.4 dB for 26 MHz bandwidthC/N of the receiving system +14.1 dBNoteTo calculate C/N exactly, it is essential that you take the RF bandwidth ofthe receiving signal into account.0+
