Link Power Budgetting : Calculation/Measurement Of Uplink To Noise Ratio
Link Power Budgetting
4.Calculation of uplink to noise ratio
1. Up link rain attenuation (dB) Rain fall results in attenuation of radio waves by scattering , and by absorption , of energy from the wave. Rain attenuation increases with increasing frequency and in worse at Ku band compared to C band. Studies have shown that the rain attenuation for horizontal polarization is considerably greater than for vertical polarization.
2. Satellite G/T (dB/k)
G/T ratio indicates figure of merit. G/T ratio is the ratio of gain of the satellite to the thermal noise temperature of the satellite. G/T ratio depends on the satellite components.
3. Uplink C/No(dB Hz)
The up link of a satellite circuit is the link in which the earth station is transmitting the signal and the satellite is receiving it .
Carrier to noise ratio of up link is given as
[C/No]U = [EIRP]U + [G/T]U - [losses]U + 228.6
=Transmitter EIRP- (Up link path losses + Up link rain attenuation) + Satellite G/T + 228.6 (dB).......
Example : calculate power rating of ground transmitter operating at following conditions Transmitter EIRP37.97 dB W, Up link rain attenuation-0.0 dB, Up link path loss 199.62 dB, satellite G/T(dB/K)-5.00
[C/No]U = 37.97 -5.00-199.92+228.6
= 61.65 dB