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Page 528 of 544 NT5D14 Line Side T-1 card
553-3011-100 Standard 14.00 January 2002
Architecture
Card interfaces
The line side T-1 card passes voice and signaling data over DS-30X loops
through the DS-30X Interfaces circuits and maintenance data over the card
LAN link.
T-1 interface circuit
The line side T-1 card contains one T-1 line interface circuit which provides
24 individually configurable voice interfaces to one T-1 link in 24 different
time slots. The circuit demultiplexes the 2.56 Mbps DS-30X Tx signaling
bitstreams from the DS-30X network loop and converts it into 1.544 mHz T-
1 Tx signaling bitstreams onto the T-1 link. It also does the opposite,
receiving Rx signaling bitstreams from the T-1 link and transmitting Rx
signaling bitstreams onto the DS-30X network loop.
The T-1 interface circuit performs the following:
• Provides an industry standard DSX-1 (0 to 655 ft/200 meters) interface.
• Converts DS-30X signaling protocol into FXO A and B robbed bit
signaling protocol.
• Provides switch-selectable transmission and reception of T-1 signaling
messages over a T-1 link in either loop or ground start mode.
Signaling and control
The line side T-1 card also contains signaling and control circuits that
establish, supervise, and take down call connections. These circuits work
with the system controller to operate the T-1 line interface circuit during calls.
The circuits receive outgoing call signaling messages from the controller and
return incoming call status information to the controller over the DS-30X
network loop.
Card control functions
Control functions are provided by a microcontroller and a Card LAN link on
the line side T-1 card. A sanity timer is provided to automatically reset the
card if the microcontroller stops functioning for any reason.