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PRELIMINARY
XRT79L71
322
REV. P2.0.0
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
The Transmit DS3/E3 Framer block is the fourth functional block (within the Transmit Direction) of the
XRT79L71 that we will discuss for E3, ITU-T G.751 Clear-Channel Framer Applications. Figure 147 presents
an illustration of the "Transmit Direction" circuitry whenever the XRT79L71 has been configured to operate in
the E3, ITU-T G.751 Clear-Channel Framer Mode, with the "Transmit DS3/E3 Framer" block highlighted.
The purpose of the Transmit E3 Framer block is to accept data from the Transmit Payload Data Input Interface
block and the Transmit LAPD Controller, and to create an E3 data-stream. Afterwards, the Transmit E3 Framer
block will route this E3 data-stream to the Transmit E3 LIU Block (for transmission to the remote terminal
equipment). The Transmit E3 Framer block also supports the following functions.
Transmitting the LOS Pattern (under Software control)
Transmitting the AIS Pattern (under Software control)
Transmitting the FERF (RDI) indicator (under Software Control, if BIP-4 Calculation and Insertion is disabled)
Transmitting the FEBE (REI) indicator (automatically, if BIP-4 Calculation and Insertion is enabled).
5.2.4.1
TRANSMITTING THE LOS PATTERN
The Transmit DS3/E3 Framer block (within the XRT79L71) permits the user to transmit the LOS (Loss of
Signal) pattern to the remote terminal equipment. In this case, the Transmit E3 Framer block will generate and
transmit an "All Zeros" pattern to the remote terminal equipment. The procedure for transmitting the LOS
Pattern is presented below.
Transmitting the LOS Pattern
FIGURE 147. ILLUSTRATION OF THE FUNCTIONAL BLOCK DIAGRAM OF THE TRANSMIT DIRECTION CIRCUITRY, WHEN-
EVER THE
XRT79L71 HAS BEEN CONFIGURED TO OPERATE IN THE E3, ITU-T G.751 CLEAR-CHANNEL FRAMER
MODE (WITH THE "TRANSMIT DS3/E3 FRAMER" BLOCK HIGHLIGHTED)
Transmit
Payload Data
Input
Interface
Block
Transmit
Payload Data
Input
Interface
Block
Transmit
DS3/E3
Framer
Block
Transmit
DS3/E3
Framer
Block
Tranmit
DS3/E3
LIU Block
Tranmit
DS3/E3
LIU Block
TxSer
TxNib[3:0]
TxInClk
TRING
TTIP
Transmit
Overhead Data
Input Interface
Block
Transmit
Overhead Data
Input Interface
Block
TxOHClk
TxOHIns
TxOHInd
TxOH
TxOHEnable
TxOHFrame
TxNibClk
TxFrame
Tx LAPD
Controller
Block
Tx LAPD
Controller
Block
From Microprocessor
Interface Block
Tx LAPD
Buffer
(90 Bytes)
Tx LAPD
Buffer
(90 Bytes)