Page 200 of 236 NTRB21 DTI/PRI/DCH TMDI card553-3023-211 Standard 1.00 June 2001Power requirementsThe DTI/PRI obtains its power from the backplane, and draws less than2 amps on +5 V, 50 mA on +12 V, and 50 mA on –12 V.Foreign and surge voltage protectionLightning protectors must be installed between an external T-1 carrier facilityand the Succession CSE 1000 system. For public T-1 facilities, this protectionis provided by the local operating company. In a private T-1 facilityenvironment (a campus, for example), the NTAK92 protection assembly canbe used.The NTRB21 circuit card conforms to safety and performance standards forforeign and surge voltage protection in an internal environment.ArchitectureSignaling interfaceThe signaling interface performs an 8 Kbps signaling for all 24 channels andinterfaces directly to the DS-30X link. Messages transmitted in bothdirections are three bytes long.InterconnectionThe interconnection to the carrier is by NTBK04, a 1.5 Mb 20 ft. carrier cable.The NT8D97AX, a fifty-foot extension cable, is also available.MicroprocessorThe NTRB21 is equipped with bit-slice microprocessors that handle thefollowing major tasks:• Task handler: also referred to as an executive. The task handler providesorderly per-channel task execution to maintain real-time task orderingconstraints.• Transmit voice: inserts digital pads, manipulates transmit AB bits forDS1, and provides graceful entry into T-Link data mode when the datamodule connected to the DTI/PRI trunk is answering the call.• Receive voice: inserts digital pads and provides graceful entry into T-Link data mode when the data module connected to the DTI/PRI trunk isoriginating the call.
