NTAK102. 0 Mb DTI card Page477 of 544
Option11C and 11C Mini Technical Reference Guide
Reference clock selection via software
The 2MB DTI card has the necessary hardware for routing its reference to the
appropriate line on the backplane
Software is responsible for the distribution of the secondary references and
ensures that no contention is present on the REFCLK1 backplane line.
Software designates the 2MB DTI Card as a primary reference source to the
clock controller. The secondary reference is obtained from another 2 Mbps
DTI card, which is designated by a craft person. No other clocks originating
from other 2MB DTI packs are used.
The clock controller provides an external timing interface and is capable of
accepting two signals as timing references. In this case, an external reference
refers to an auxiliary timing source which is bridged from a traffic carrying
signal. This is not intended to be a dedicated non-traffic bearing timing signal.
The clock controller uses either the two external/auxiliary references or the
2MB DTI references.
Reference clock interface
The recovered clock derived from the facility is available on the MDF
connector. The signals at these connectors conform to the electrical
characteristics of the EIA RS-422 standard.
Switch settingsVarious 2MB DTI switchable options exist on the NTAK10. These are:
Switch Off
(Switch Open)
On
(Switch Closed)
S1-1 - -
S1-2 CC Enabled CC Disabled
S2-1 120 ohm 75 ohm
S2-2 75 ohm 120 ohm
S3-1 non-French Firmware French Firmware
S3-2 - -