Satellite Coordination Calculation & Software

Presentation / Satellite Coordination Calculation & Software

Date Submitted: 04 October 2001

Written by RPC Telecommunications. Website:

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A lecture covering satellite coordination calculation. Both the software, and manual sides of calculation are covered.

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-Section 1
Coordination Tasks
-Section 2
Link & Interference Analysis
-Section 3
Protection Ratio Analysis
-Section 4
Databases, Data Gathering and Processing
-Section 5
ITU Software Tools
-Section 6
Proprietary Software Tools
-Section 7
Link & Interference Analysis
Link budget refresher:
  • Received Carrier Power:
    Pr = Pt + Gt Lp + Gr (dBW)
  • Received Noise Power:
    Pn = 10 log (k T B) (dBW)
  • Carrier to Noise Ratio:
    C/N = Pt Pn
    = Pt + Gt Lp + Gr 10 log (T) - 10 log (B) 10 log (k) (dB)

Carrier to Interference refresher:

  • Received Wanted Carrier Power:
    Pw = Pt + Gt (θ) Lp + Gr (φ) (dBW)
  • Received Interfering Carrier Power
    Pi = Pt + Gt(θ) Lp + Gr(φ) (dBW)
  • So carrier to interference ratio:
    C/I = Pw Pi
    = [Pt + Gt (θ) Lp + Gr (φ)] [Pt + Gt(θ) Lp + Gr(φ)]

Normally simplify by assuming that Lp = Lp.
Note that the Gr terms both refer to the same antenna (the receiving system gain).

Define receive antenna discrimination, Dr = Gr (φ) - Gr (φ), typically 3 or 4 dB for a satellite receive antenna, generally much higher, say +20 to +40 dB for an earth station receive antenna.

So simplify terms:
C/I = Pt + Gt (θ) + Dr Pt Gt(θ) (dB)

This is a very simple equation; satellite to satellite coordination is not technically difficult to analyse!

Some additional complications to bear in mind:

  • Pt and Pt can be power spectral densities (dBW/Hz) or powers (dBW).
  • If Pt and Pt are densities then strictly you have calculated Co/Io not C/I (Co/Io ~ C/I for digital carriers).
  • If Pt and Pt are powers then they may have different bandwidths - normalise C/I inside the bandwidth of the wanted carrier.

Next: Section 3 - Protection Ratio Analysis


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