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throughput and link state). While having this screen displayed, you
may press Enter to display line attenuation in dB (proper value appears
only after the line synchronizes):
Pressing Enter again will show so-called Noise Margin (or Signal-
Noise Ratio). This is the difference between the useful signal and the
background noise. It may be used to estimate, how much the line rate
may be increased without causing any problems with the
synchronization.
When the NMR is less than 0 dB modems will be unable to bring
the link up.
It is the best practice to keep the NMR equal to or higher than 5
dB, so the error rate will be unnoticeable. Otherwise the packets will be
lost due to bit errors and the retransmission would be necessary, thus
decreasing the overall effective throughput. This parameter is also
valid only when the lines are fully synchronized.
Pressing Enter again will return to the main screen with the
throughput and modem state.
8
ATT:
6.0
(dB)
6.5
NMR: 10.0
(dB) 10.5
7.0
6.0
9.5
9.0
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