Nortel Networks 553-3001-211 manual T1 interface circuit, Signaling and control

Page 188 of 894 NT5D11 and NT5D14 Lineside T1 Interface cards

Card interfaces

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.

T1 interface circuit

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.

Signaling and control

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.

Card control functions

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.

553-3001-211 Standard 2.00 September 2004