Nortel Networks 553-3001-211 manual Switch SW4 Carrier Shield Grounding, Switch SW4 Down On Up Off

NTAK79 2.0 Mb PRI card Page 739 of 894

Switch SW4 – Carrier Shield Grounding

This switch enables for the selective grounding of the Tx / Rx pairs of the carrier cable. Closing the switch (down position) applies Frame Ground (FGND) to the coaxial carrier cable shield, creating a 75 ohms unbalanced configuration. This applies only to the NTBK05CA cable.

Table 238

Switch SW4

Switch	Down (On)	Up (Off)
SW 4-1	Rx – FGND	Rx – OPEN
SW 4-2	Tx – FGND	Tx – OPEN

Note: The usual method is to ground the outer conductor of the receive coaxial signal.

Power requirements

The NTAK79 obtains its power from the backplane, drawing maximums of 2 A on +5 V, 50 mA on +12 V and 50 mA on –12 V.

Environment

The NTAK79 meets all applicable Nortel Network’s operating specifications.

Functional description

The NTAK79 card provides the following features and functions:

•recovery of the 2.048 kbps data by the CEPT receiver, at signal levels which have been attenuated by up 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)

Circuit Card Description and Installation