Nortel Networks Video Gaming Accessories 553-3001-211 Manual De Usuario

 NTAK10 2.0 Mb DTI card

converted from digital to AMI and sent to the carrier. A transformer provides 
isolation and impedance matching (75 ohms or 120 ohms).

The AMI data of the carrier is converted to digital and fed to the input selector 
as well as the output selector for far end loopback. Clock recovery circuitry 
within the receiving device extracts the 2.0 MHz clock. This clock generates 
the frame and multiframe count and sends them to the clock controller as a 
reference.

The recovered clock from the external digital facility is provided to the clock 
controller through the backplane-to-clock controller interface. Depending 
upon the state of the clock controller (switched on or off), the clock controller 
interface, in conjunction with software, enables or disables the appropriate 
reference clock source.

The clock-controller circuitry on NTAK10 is identical to that of the 
NTAK20. While several DTI/PRI packs can exist in one system, only one 
clock controller can be activated. All other DTI/PRI clock controllers must be 
switched off.

Note: Clocking slips can occur between MG 1000S systems that are 
clocked from different Central Offices (COs), if the COs are not 
synchronized. The slips can degrade voice quality.

The clock controller can operate in one of two modes: tracking or 
non-tracking (also known as free-run).

Each MG 1000S that has a digital trunk must have a clock controller 

clocked to an external reference clock.