Nortel Circuit Card, Installation Manual, Page: 757 / 908

NTAK79 2.0 Mb PRI card Page 757 of 906
Circuit Card Description and Installation
• receive clock output
• transmit clock output
The receive and transmit clocks have slightly different bit rates from each
other, as determined by the transmit and receive carrier clocks.
The NTAK79 has an onboard D-Channel Handler Interface (DCHI). It is the
equivalent to a single port of an NTAK02 SDI/DCH pack. This enables for a
completely operational ISDN PRA link with clock synchronization and
D-channel on a single circuit card.
The onboard D-channel has one status LED on the NTAK79 faceplate to
indicate enabled/disabled states. See Table 239 on
page 746 .
The on-board DCHI can be operated in two separate modes as defined by an
on-board dip switch. It can operate in a standard DCHI mode common to
most ISDN standard countries. The U.K. specific mode that uses the DPNSS
format is not supported at this time.
DCHI special applications connection
The connection between the PRI2 and the on-board D-channel Handler
Interface card is also available at the MDF connector. Connections are made
to these pins for normal on-board DCHI operation. They can also be used for
future or special applications.
The signals conform to the EIA RS-422 standard.
Table 247
Settings for the DCHI dip switch (SW1)
Switch Function On Off
S1-1 En/Dis Enabled Disabled
S1-2 F/W Mode DPNSS (not
supported at
this time)
DCHI