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

 NTRB21 DTI/PRI/DCH TMDI card

The NTRB21 is equipped with bit-slice microprocessors that handle the 
following major tasks:

•

Task handler: also referred to as an executive. The task handler provides 
orderly per-channel task execution to maintain real-time task ordering 
constraints.

•

Transmit voice: inserts digital pads, manipulates transmit AB bits for 
DS1, and provides graceful entry into T-Link data mode when the data 
module 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 
is originating the call.

•

T-Link data: a set of transmit and receive vectored subroutines which 
provides T-Link protocol conversion to and from the DM-DM protocol. 

•

Receive ABCD filtering: filters and debounces the receive ABCD bits 
and provides change of state information to the system.

•

Diagnostics

•

Self-test

The digital pad is an EPROM whose address-input to data-output transfer 
function meets the characteristics of a digital attenuator. The digital pad 
accommodates both µ255-Law and A-Law coding. There are 32 
combinations each for µ255 to µ255, µ255 to A-Law, A-Law to µ255, and 
A-Law to A-Law. These values are selected to meet the EIA loss and level 
plan.