Nortel Networks Circuit Card - Manual (Page 777)

NTBK50 2.0 Mb PRI card Page 777 of 906
Circuit Card Description and Installation
Power requirements
The NTBK50 obtains its power from the backplane, drawing up to 2 A on +5
V, 35 mA on +15 V and 20 mA on –15 V.
Environment
The NTBK50 meets all applicable Nortel operating specifications.
Functional description
NTBK50 provides the following features and components:
• recovery of the 2.048 kbps data by the CEPT receiver, at signal levels
which have been attenuated by up to 10 dB
• control of CEPT line density using HDB3 which provides 64 kbps clear
channel
• performance monitoring of the receive carrier by means of Bipolar
Violations (BPV), Slips, CRC-4 (CRC), and Frame Bit Errors (FBER)
Flashing
(Green) NTAK20 is equipped and is attempting to lock (tracking
mode) to a reference. If the LED flashes continuously
over an extended period of time, check the CC STAT in
LD 60. If the CC is tracking this can be an acceptable
state. Check for slips and related clock controller error
conditions. If none exist, then this state is acceptable,
and the flashing is identifying jitter on the reference.
Off The clock controller is not equipped.
DCH On (Red) DCH is disabled.
On (Green) DCH is enabled, but not necessarily established.
Off DCH is not equipped.
Table 249
NTBK50 faceplate LEDs (Part 2 of 2)
LED State Definition