Nortel Circuit Card Installation Manual page 200

Page 200 of 906
Card interfaces
T1 interface circuit
Signaling and control
Card control functions
553-3001-211 Standard 3.00
NT5D11 and NT5D14 Lineside T1 Interface cards
The lineside T1 card passes voice and signaling data over DS-30X loops
through the DS-30X Interfaces circuits and maintenance data over the card
LAN link.
The lineside T1 card contains one T1 line interface circuit which provides 24
individually configurable voice interfaces to one T1 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 T1
Tx signaling bitstreams onto the T1 link. It also does the opposite, receiving
Rx signaling bitstreams from the T1 link and transmitting Rx signaling
bitstreams onto the DS-30X network loop.
The T1 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 T1 signaling
messages over a T1 link in either loop or ground start mode.
The lineside T1 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 T1 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.
Control functions are provided by a microcontroller and a Card LAN link on
the lineside T1 card. A sanity timer is provided to automatically reset the card
if the microcontroller stops functioning for any reason.
August 2005