ZyXEL Communications U-336R/RE manual Line Condition Status Display, Diagnostics & Troubleshooting

Dialing Indicator

The V34 LED will flash on and off for 1/2 second intervals 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 during 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 for 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:

ONOTE: READINGS ARE ONLY AVAILABLE WHEN USING THE U-336R/REINSTALLED IN RS-1612RACK SYSTEM. THE READINGS DISPLAYED ARE NOT MEASUREMENTS AND SHOULD ONLY BE USED AS A REFERENCE.

Signal to Noise Ratio (S/N)

This reading is expressed in 1 dB resolution. The higher the speed, the higher the S/N ratio required. The modem measures the S/N ratio by measuring the distance between the demodulated signal point and the ideal signal point. For V.32/V.32bis, the modem- measured S/N ratio is generally about 2 dB higher than what is actually on the line because the modem rejects some of the out-of- band noise. For V.22/22bis, the difference can be as high as 8 dB because the modem only uses part of the 3 KHz bandwidth and rejects more than half of the voice band noise.

120 Diagnostics & Troubleshooting