Viavi OneExpert CATV 630, Extended Quick Start Manual

Page: 105 / 183

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101
Physical Measurements (Level, MER)

MER 2 percentile shows how
well 98% of the subcarriers are
working and filters out
underperforming ones that
LDPC error correction will likely
clear up.
THINGS TO CHECK:
Avg level, variable:
>-6 dBmV recommended
Avg MER, variable:
>36 dB recommended
MER at 2 percentile:
>35 dB recommended
MER standard deviation:
<2 dB recommended
OFDM Avg power must be within range. Good
MER and low noise enable higher modulations.
CM Minimum CNR/MER
Performance in AWGN
Channel
Modulation
Up to 1 GHz
CNR(dB)
Min P
6AVG
dBmV
4096 41.0 -6
2048 37.0 -9
1024 34.0 -12
512 30.5 -12
256 27.0 -15
128 24.0 -15
64 21.0 -15
16 15.0 -15
MER
PCTL
2%
MER
Std Dev
<2dB
MER
>35dB
42 dB
MER Avg