Nortel Networks Circuit Card 311 - Manual (Page 700)

700 NT8D14 Universal Trunk card
Balance network for loop lengths (Note 2)
Trunk types
Terminating
impedance
(Note 1)
0–915 m
(0–3000 ft)
915–1524 m
(3000–5000 ft)
> 1524 m
(> 5000 ft)
DID (loop length
< 600 ohms) 600
or
900
ohms
600 ohms 3COM 3CM2
DID (loop length
ˇ
S 600 ohms)
600 or 900
ohms 600 ohms N/A 3CM2
RAN: continuous
operation mode 600 or 900
ohms 600 or 900 ohms N/A N/A
Paging 600 ohms 600 ohms N/A N/A
Note 1: The terminating impedance of each trunk unit is software selectable in LD 14 and should
match the nominal impedance of the connecting equipment.
Note 2: The balance network of each trunk unit is software selectable between resistive 600 or
900 ohms or 3COM and jumper selectable between 3COM and 3CM2. Jumper selection for
3COM/3CM2 restriction does not apply to NT8D14BB (Release 10 and later).
Table 258
Cable loop resistance and loss
Cable loop resistance (ohms)
Cable loop loss (dB)
(nonloaded at 1kHz)
Cable length 22 AWG 24 AWG 26 AWG 22 AWG 24 AWG 26 AWG
915 m (3000 ft) 97 155 251 0.9 1.2 1.5
1524 m (5000 ft) 162 260 417 1.6 2.0 2.5
2225 m (7300 ft) 236 378 609 2.3 3.0 3.7
3566 m (11700 ft) 379 607 977 3.7 4.8 6.0
5639 m (18500 ft) 600 960 1544 5.9 7.6 9.4
The trunk type, terminating impedance, and balance network are selected
by making service change entries in the Trunk Administration program LD
14. See
Table 257 "Trunk types - termination impedance and balance
network (NT8D14BA, NT8D14BB)" (page 699) for the proper values for the
trunk type and loop length. Refer to Software Input/Output Reference —
Administration (NN43001-611) for LD 14 service change instructions.
Before the appropriate balance network can be selected, the loop length
between the near-end (CS 1000) and the far-end (a Central Office, for
example) must be known. To assist in determining loop length, some typical
Nortel Communication Server 1000
Circuit Card Reference
NN43001-311 01.04 Standard
Release 5.0 23 May 2008
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