BT8954 CONEXANT [Conexant Systems, Inc], BT8954 Datasheet - Page 35

• Manufacturer Part Number: BT8954
• Description: VOICE PAIR GAIN FRAMER
• Manufacturer: CONEXANT [Conexant Systems, Inc]

Bt8954
Voice Pair Gain Framer
Figure 3-11. LFSR Structure for Transmission in the Central Office
3.4.6 2B1Q Encoder
N8954DSC
Scrambled Input (b
Polynomial: ck = xk-23
+
x
k-16
z
k
-1
)
x
z
k-1
-1
+
x
k-15
xk-5
z
z
-1
-1
The 2B1Q encoder converts the data to be transmitted to the bit pump into sign
and magnitude data according to the quaternary alignment provided on the QCLK
input.
outputs on TDAT.
Table 3-3. 2B1Q Encoder Alignment
x
x
z
k-17
k-2
-1
+
b
Table 3-3
x
k
k-14
z
z
First Input Bit
-1
-1
(Sign)
x
x
z
k-18
k-3
-1
0
0
1
1
depicts how sign and magnitude bits generate 2B1Q coded
x
z
k-13
z
-1
-1
Conexant
x
+
x
z
z
k-19
k-4
-1 = Delay Element (D flip-flop clocked with BCLK)
-1
= modulo-2 summation (XOR gate)
x
k-12
z
z
-1
-1
+
x
x
k-5
k-20
z
Remote Direction
-1
Second Input Bit
(Magnitude)
z
x
k-11
-1
z
-1
0
1
1
0
x
k-6
z
x
k-21
-1
z
x
k-10
-1
z
-1
x
z
x
k-7
k-22
-1
Unscrambled Output (ck)
3.0 Circuit Descriptions
z
x
Quaternary Symbol
-1
z
k-9
-1
x
k-8
x
z
k-23
-1
3.4 Transmitter
–3
–1
+1
+3
3-13