– 7859 –
p.
61
12.12 DVB-S et DSS
Display of the measures of:
BERi
:
error rate before Viterbi
BERo
:
error rate after Viterbi
PER
:
error rate after Reed Solomon (error rate packet)
MER
:
modulation error rate
LKM
:
Noise margin (Link Margin)
BERx
: error rate ‘bits’
Ratio between the number of false bits / number of transmitted bits during the measurement time
PER
: error rate ‘packets’
Ratio between the number of false packets / number of transmitted packets during the measure-
ment time
Recall: Under QPSK (DVB-S) a packet is made of 204 octets; a packet is "false" if it includes more than 8
wrong octets (correction by Reed Solomon coding). Under DSS, a packet is made of 146 octets.
TUNER
DEMODULATEUR
VITERBI
REED
SOLOMON
DECODAGE
MPEG
BERi
BERo
PER