TFRA08C13-DB AGERE [Agere Systems], TFRA08C13-DB Datasheet - Page 31

• Manufacturer Part Number: TFRA08C13-DB
• Description: TFRA08C13 OCTAL T1/E1 Framer
• Manufacturer: AGERE [Agere Systems]

Preliminary Data Sheet
October 2000
Lucent Technologies Inc.
Lucent Technologies Inc.
LIU-Framer Interface
Line Encoding
Single Rail
The default line code is single-rail mode and single-rail function of the framer specified by FRM_PR8 bit 7 = 1,
bit 6 = 1, and bit 5 = 0. In this mode, the framer bipolar encoder/decoder is disabled and monitoring of received
BPV errors is done with the use of the RND input. When RND = 1, the BPV counter increments by one on the rising
edge of RLCK.
The transmit framer transmits data via the TPD output pin while TND is forced to a 0 state.
Dual Rail
In dual-rail mode, the dual-rail function of the framer is selected through FRM_PR8 bits 5—7. Bipolar encoding/
decoding is enabled in the framer. Noncoded/decoded data is exchanged between the LIU and framer via the RPD,
RND, RCLK, TPD, TND, and TCLK LIU-framer interface.
DS1: Alternate Mark Inversion (AMI)
The default line code used for T1 applications is alternate mark inversion (AMI). The coding scheme represents a 1
with a pulse or mark on the positive or negative rail and a 0 with no pulse on either rails. This scheme is shown in
Table 3.
Table 3. AMI Encoding
The T1 ones density rule states that: In every 24 bits of information to be transmitted, there must be at least three
pulses, and no more than 15 zeros may be transmitted consecutively.
Receive ones density is monitored by the receive line interface as per T1M1.3/93-005, ITU G.775, or TR-TSY-
000009.
The receive framer indicates excessive zeros upon detecting any zero string length greater than 15 contiguous
zeros (no pulses on either RPD or RND). Both excessive zeros and coding violations are indicated as bipolar viola-
tions.
DS1: Zero Code Suppression (ZCS)
Zero code suppression is a technique known as pulse stuffing in which the seventh bit of each time slot is stuffed
with a one. The line format (shown in Table 4) limits the data rate of each time slot from 64 kbits/s to 56 kbits/s.
The default ZCS format stuffs the seventh bit of those ALL-ZERO time slots programmed for robbed-bit signaling
(as defined in the signaling control registers with the F and G bits).
Input Bit Stream
AMI Data
–0+–
1011
(continued)
0000
0000
0+–+
0111
–0+0
1010
TFRA08C13 OCTAL T1/E1 Framer
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