Satellite Link Budget Caculations Formula Set
Reference=Intelsat Earth Station Technology Handbook, Rev. 3, Dec 1994

• longdiff=satlong-eslong
Azimuth=180+atan(tan(longdiff)/sin(eslat))

• r=6378.14 Km Earth Radius
S=42164.57 Km Satellite Orbit Radius
Range=sqrt(r^2+S^2-2.r.S.cos(eslat).cos(longdiff))
Elevation=atan( (Range^2+r^2-S^2)/(2.Range.r) )

• n=antenna efficiency
f=frequency in GHz
d=diameter in m
Antenna Gain=10.log(n)+20.log(f.d)+20.4
Gain for 1m^2 antenna=20.log(f)+21.4

• Transmit EIRP

10log(transmit power)+transmit Gain

• Free Space Loss
L=20.log(f.Range)+92.5

• Equivalent Noise Temperature
F=Noise Figure
To=Ambient temperature 290K
Te=(F-1).To

• Receiver Total System Noise Temperature
L=feed loss in numeric, 10^(dBloss/10)
Tant=Antenna Noise Temperature
Tsystem=Tant/L+(1-1/L).To+Te

• G/T
G/T=Gain-10.log(Tsystem)

• C/N, C/No, C/T
C/N=EIRP-free space loss+G/T-10.log(BW)+228.6
C/No=EIRP-free space loss+G/T+228.6
Eb/No=C/No-10.log(Rate)

• Uplink Flux Dencity
W=EIRP(uplink)-20.log(Range)-71
W=EIRP(uplink)-free space loss+Gain of 1m^2 antenna

• Datarate - Bandwidth Relation
Bandwidth (MHz) = Data Rate (Mbps) * (1+a^2) / (FEC*M)
FEC: Forward Error Correction, Viterbi and Reed Solomon. (If both used, multiply together)
M= Modulation Coding level (2=QPSK, 3=8PSK, 4=16QAM, 4=8VSB)
a = Spectral shaping; 0.2 typical