Microprocessor - Nortel Enterprise 1000 Reference Manual

Page 140 of 236

Microprocessor

Digital pad
Table 31
Digital pad values and offset allocations (Part 1 of 2)
Offset
0
1
2
553-3023-211 Standard 1.00 June 2001
NTAK09 1.5 Mb DTI/PRI card
The NTAK09 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/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.
PAD set 0
0dB
2dB
3dB
PAD set 1
–7db
–8db
–9db