
XRT79L71
PRELIMINARY
155
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
REV. P2.0.0
The Transmit Line Driver Block
The Transmit Drive Monitor Block
4.2.6.1
The B3ZS Encoder Block
The purpose of the B3ZS Encoder block is to encode the outbound DS3 traffic into the B3ZS Line Code. In the
case of the XRT79L71, the B3ZS Encoder block will always be enabled, and the user has no ability to disable
the B3ZS Encoder block.
4.2.6.2
The Jitter Attenuator Block
The XRT79L71 includes a Jitter Attenuator block that can be configured to operate in either the Transmit
Direction (e.g., within the Transmit DS3/E3 LIU Block) or in the Receive Direction (e.g., within the Receive
DS3/E3 LIU Block). The purpose of the Jitter Attenuator block is to permit the XRT79L71 to comply with all of
the following Jitter Transfer Characteristic requirements.
Bellcore GR-499-CORE Category II to Category II Interfaces (DS3 Applications)
TBR-24 34Mbps D34U and D34S System Requirements (for E3 Applications)
Each of these requirements, and how the XRT79L71 performs against these requirements is described in
detail below.
4.2.6.2.1
The Basic Architecture of the Jitter Attenuator Block
Figure 69 presents an illustration of the Functional Block Diagram of the Jitter Attenuator Block
According to Figure 69 the Jitter Attenuator consists of the following functional blocks.
The Timing Control/Phase-Locked Loop Block
FIGURE 69. AN ILLUSTRATION OF THE FUNCTIONAL BLOCK DIAGRAM OF THE JITTER ATTENUATOR BLOCK
Timing Control
Block/
Phase Locked
Loop
Timing Control
Block/
Phase Locked
Loop
In_POS
In_NEG
In_CLK
Write_Clock
Read_Clock
Out_POS
Out_NEG
Out_CLK
Microprocessor
Interface
16/32 Bit FIFO
Jittery Clock
Smoothed Clock
FL
DS3Clk/E3Clk
Or SFM-Derived
Line Code
JA_RESET