Nortel Circuit Card Installation Manual page 835

• receive clock output
• transmit clock output
The bit rate of the receive and transmit clocks can vary slightly from each
other. This is determined by the transmit and receive carrier clocks.
Feature selection through software configuration for the D-channel includes:
• 56 kbps
• 64 kbps clear
• 64 kbps inverted (64 Kbps restricted)
DCHI can be enabled and disabled independent of the PRI card, as long as the
PRI card is inserted in its cabinet slot. The D-channel data link cannot be
established unless the PRI loop is enabled.
On the NTRB21 use switch 1, position 1 to select either the D-channel feature
or the DPNSS feature, as follows:
OFF = D-channel
The ON setting for DPNSS (U.K.) is not supported at this time.
DS-1 Carrier interface
Transmitter
The transmitter takes the binary data (dual unipolar) from the PCM
transceiver and produces bipolar pulses for transmission to the external
digital facility. The Digital Signal – Level 1 (DS-1) transmit equalizer enables
the cabling distance to be extended from the card to the Digital Signal
NTRB21 DTI/PRI/DCH TMDI card
Circuit Card
Page 835 of 906
Description and Installation