Technical Appendix
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Technical Appendix
Signal-to-Noise-Ratio
The following values must be known in order to determine the
carrier/signal-to-noise-ratio (C/N):
• Basic noise level (adjust the dish antenna so that no satellite signal
will be received)
• Maximum reception level
• Bandwidth correction
The following formula applies:
C/N = Received signal level – Basic signal-to-noise-ratio – Bandwidth correction
6 MHz (Measurement bandwidth MSK 25)
Bandwidth correction value = 10 log ---—————————————–--
RF bandwidth received signal
Bandwidth correction value = 6.37 dB at 26 MHz bandwidth (ASTRA)
Bandwidth correction value = 7.78 dB at 36 MHz (EUTELSAT, INTELSAT, Kopernikus)
Example
Received-signal level +75.5 dB With satellite signal
Basic signal-to-noise-ratio -55.0 dB
Without satellite signal
Carrier/signal-to-noise-ratio (C/N) +20.5 dB
Bandwidth correction - 6.4 dB
For 26 MHz bandwidth
C/N of reception system
+14.1 dB
Note
It is essential to consider the RF bandwidth of the received signal in order
to be able to accurately determine the C/N.
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