Functional Description - Nortel Circuit Card Installation Manual

Table 249
NTBK50 faceplate LEDs (Part 2 of 2)
LED
DCH
Power requirements
Environment

Functional description

State Definition
Flashing NTAK20 is equipped and is attempting to lock (tracking
(Green) 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.
On (Red) DCH is disabled.
On (Green) DCH is enabled, but not necessarily established.
Off DCH is not equipped.
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.
The NTBK50 meets all applicable Nortel operating specifications.
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)
NTBK50 2.0 Mb PRI card
Circuit Card Description and Installation
Page 777 of 906