NTRB21DTI/PRI/DCH TMDI card Page463 of 544
Option11C and 11C Mini TechnicalReference Guide
D-channel interface
The D-channel interface is a 64 Kbps, full-duplex, serial bit-stream
configured as a DCE device. The data signals include receive data output,
transmit data input, receive clock output, and transmit clock output. The
receive and transmit clocks can be of slightly different bit rate from each other
as 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 however, 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
ON = DPNSS (U.K.).