Nortel Networks Option 11C Manuale Utente
Page 462 of 544
NTRB21 DTI/PRI/DCH TMDI card
Digital pad
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.
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.
Table 144
Digital pad values and offset allocations
Digital pad values and offset allocations
Offset
PAD set 0
PAD set 1
0
0dB
-7db
1
2dB
-8db
2
3dB
-9db
3
4dB
-10db
4
5dB
0.6db
5
6.1dB
7db
6
8dB
9db
7
-1dB
10db
8
-3dB
11db
9
-4dB
12db
A
idle code, 7F
3db
B
unassigned code, FF
14db
C
1dB
spare
D
-2dB
spare
E
-5db
spare
F
-6db
spare