Indicator Lights; Line Condition Status Display - ZyXEL Communications U-336S User Manual

Indicator Lights

Retransmission Indicator
In the error control mode, an error occurring in the link will cause the
data to be re-transmitted. At the same time, the AA LED will flash. This
also indicates the quality of the line.
Dialing Indicator
The V34 LED will flash on and off for 1/2 second each to indicate that
the modem is dialing. This flash will continue after dialing until a carrier is
detected. Therefore, the V34 LED will also flash in leased-line modem
connections when one modem is trying to handshake but the other
modem is not turned on.
Handshaking And Retrain Indicator
The V34 LED will flash on and off in 1/2 second intervals to indicate
that the modem is handshaking or retraining.

Line Condition Status Display

Regarding data being transmitted over telephone line circuits, there are
many kinds of line impairments that can affect the data being received
by the remote modem.
Your modem can measure four major line impairments. From the
impairment readings, you can understand the current line condition.
Your modem also logs line events over a long period, so you know
what the line condition has been. We will describe these readings and
logs as follows:
: T
ON
OTE HE READINGS DISPLAYED ARE NOT MEASUREMENTS AND SHOULD ONLY BE
USED AS A REFERENCE
Signal to Noise Ratio (S/N)
This reading is expressed in 0.1 dB resolution. The higher the speed, the
higher the S/N ratio required. The modem measures the S/N ratio by
132 Diagnostics & Troubleshooting
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