Nortel NT1R20, Description

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NT1R20 Off-Premise Station Analog Line Card Page 71 of 290
Line cards Description
Transmission considerations
The transmission performance of OPS lines is dependent on the following
factors:
— the Meridian 1 port-to-port loss for connections between OPS ports and
other Meridian 1 ports
— the transmission parameters of the facilities between the Meridian 1 OPS
port and the off-premise station or termination
— the electrical and acoustic transmission characteristics of the termination
These factors must be considered when planning applications using the OPS
analog line card. They are of particular importance when considering
configurations other than the traditional OPS application shown in Figure 20.
The discussion which follows is intended to provide basic transmission
planning guidelines for various OPS applications.
Port-to-port loss
Loss is inserted between OPS analog line card ports and other Meridian 1
ports in accordance with the Meridian 1 loss plan. This plan determines the
port-to-port loss for each call. When a port is configured for OPX
class-of-service, loss is programmed into the OPS analog line card on a
call-by-call basis. When configured for ONP class-of-service, an OPS analog
line card port is programmed to a value that is fixed for all calls. However,
the loss in the other port involved in the call may vary on a call-by-call basis
to achieve the total loss scheduled by the plan. Summary of transmission
parameters (553-2201-182) shows the specific loss for each possible
port-to-port combination.
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. Of that total, the loss in the facility between the PBX
and the terminal should not exceed 4.5 dB (see Figure 20).