Let us take the most common situation, i.e. rain fade. Can someone
explain to me its quantitative impact on BER.
If no countermeasure is taken, a satellite link using QPSK and no FEC goes
from 1e-8 BER to 1e-3 with only 5 dB of signal attenuation. With FEC, less
dB's are needed. In general, however, you must account for power margin,
so there is no general answer. Also, experimental systems such as ACTS and
our old FODA/IBEA use fade countermeasure adaptive techniques, even if I
don't know if any commercial system uses such methods.
--
Francesco Potorti` (researcher) Voice: +39-050-593 203 (op. 211)
Computer Networks Group Fax: +39-050-904052
CNUCE-CNR, Via Santa Maria 36 Email: [email protected]
56126 Pisa - Italy Web: http://fly.cnuce.cnr.it/
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