Nortel Circuit Card Installation Manual page 555

Analog line interface
Input impedance
The impedance at tip and ring is 600 ohms with a return loss of:
• 20 dB for 200-500 Hz
• 26 dB for 500-3400 Hz
Insertion loss
On a station line-to-line connection, the total insertion loss at 1 kHz is
6 dB + 1 dB. This is arranged as 3.5 dB loss for analog to PCM, and 2.5 dB
loss for PCM to analog.
Frequency response
The loss values in Table 178 are measured relative to the loss at 1 kHz.
Table 178
Analog message waiting line card – frequency response
Frequency (Hz)
Message channel noise
The message channel noise C-weighted (dBrnC) on 95 percent of the
connections (line to line) with both ends terminated in 600 ohms does not
exceed 20 dBrnC.
NT8D09 Analog Message Waiting Line card
60
200
300
3000
3200
3400
Minimum (dB)
20.0
0.0
–0.5
–0.5
–0.5
0.0
Circuit Card Description and Installation
Page 555 of 906
Maximum (dB)
—
5.0
1.0
1.0
1.5
3.0