Nortel Networks 553-3001-211 manual Port-to-port loss

Page 178 of 894 NT1R20 Off-Premise Station Analog Line card

Port-to-port loss

Loss is inserted between OPS analog line card ports and other ports in accordance with the loss plan. This plan determines the port-to-port loss for each call.

When a port is configured for CLS OPS, loss is programmed into the OPS analog line card on a call-by-call basis. When configured for CLS ONS, an OPS analog line card port is programmed to a value that is fixed for all calls. The loss in the other port involved in the call can vary on a call-by-call basis to achieve the total loss scheduled by the plan.

For satisfactory transmission performance, particularly on connections between the public network and an OPS termination, it is recommended that facilities conform to the following:

•Total 1 kHz loss from the local serving CO to the OPS terminal should not exceed 7.0 dB. The total loss in the facility between the PBX and the terminal must not exceed 4.5 dB. See Figure 25 on page 176.

The following requirements are based on historic Inserted Connection Loss (ICL) objectives:

—PBX – CO trunk: 5 dB with gain; 0 – 4.0 dB without gain

—OPS line: 4.0 dB with gain; 0 – 4.5 dB without gain

Economic and technological changes have led to modifications of these objectives. But since the loss provisions in the PBX for OPS are constrained by regulatory requirements as well as industry standards, they are not designed to compensate for modified ICL designs in the connecting facilities.

•Nortel Networks recommends that the attenuation distortion (frequency response) of the OPS facility be within ±3.0 dB over the frequency range from 300 to 3000 Hz. It is desirable that this bandwidth extend from 200 to 3200 Hz.

•The terminating impedance of the facility at the OPS port be approximately that of 600 ohms cable.

If the OPS line facility loss is greater than 4.5 dB but does not exceed 15 dB, line treatment using a switched-gain Voice Frequency Repeater (VFR) will extend the voice range.

553-3001-211 Standard 2.00 September 2004