Transmitting Digital Television Signals by Satellite - DVB-S/S2 - Digital Video and Audio Broadcasting Technology - page 259

A geostationary satellite is “parked” in an orbit of 35800 km above the
equator. This is the only orbit in which it can travel around the Earth syn-
chronously. At 45 o latitude, the distance from the Earth's surface is then

d = Earth's radius • sin(45°) + 35800 km = 6378 km • sin(45°)
+ 35800 km = 37938 km;

Transmitted power (e.g. Astra 1F):

Assumed transponder output power: 82 W = 19 dBW
Gain of the transmitting antenna 33 dB
Satellite EIRP (equivalent isotropic radiated power) 52 dBW

Free space attenuation:
Satellite-Earth distance = 37,938 km 91.6 dB

Transmitting frequency = 12.1 GHz 21.7 dB

Loss constant 92.4 dB

Free space attenuation 205.7 dB

Received power:
Satellite EIRP 52.0 dBW

Free space attenuation 205.7 dB

Clear sky attenuation 0.3 dB

Receiver directional error 0.5 dB

Polarisation error 0.2 dB

Received power at the antenna -154.7 dBW

Antenna gain 37 dB

Received power -117.7 dBW

Noise power at the receiver:
Boltzmann's constant

-228.6 dBW/K/Hz

Bandwidth = 33 MHz 74.4 dB

Temperature 20 o C = 273K+20K = 293K 24.7 dB

Noise figure of the LNB 1.0 dB

Noise power -128.5 dBW

Carrier/noise ratio C/N:
Received power C -117.7 dBW

Noise power N -128.5 dBW

C/N 10.8 dB