Nortel Networks Circuit Card User Manual
Page 716 of 906
NTAK09 1.5 Mb DTI/PRI 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. See Table 231.
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. See Table 231.
Table 231
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