XRT79L71
PRELIMINARY
179
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
REV. P2.0.0
The purpose of the Receive DS3/E3 LIU Block is to accept an DS3/E3 line signal and to perform all of the
following operations on this data.
To be able to receive a distorted DSX-3 signal, that has been attenuated by at least 450 feet of cable loss,
along with an additional 6dB of flat or resistive loss in an error-free manner.
To perform Clock and Data Recovery on this incoming DS3 line signal.
To declare and clear the LOS (Loss of Signal) defect condition
To declare and clear the LOL (Loss of Lock) defect condition
To decode this incoming DS3 line signal from the B3ZS line code, back into a binary data-stream, prior to
routing this signal to the Receive DS3/E3 Framer block.
To be able to comply with the Category I and II Jitter Tolerance Requirements per Bellcore GR-499-CORE
This particular section will describe the functionality and configuration options of the Receive DS3/E3 LIU
Block for DS3 applications. The functionality and configuration options of the Receive DS3/E3 LIU Block for
Figure 83 presents a more detailed illustration of the Receive DS3/E3 LIU Block within the XRT79L71.
FIGURE 82. ILLUSTRATION OF THE FUNCTIONAL BLOCK DIAGRAM OF THE RECEIVE DIRECTION CIRCUITRY, WHEN-
EVER THE
XRT79L71 HAS BEEN CONFIGURED TO OPERATE IN THE DS3 CLEAR-CHANNEL FRAMER MODE (WITH THE
RECEIVE DS3 LIU BLOCK HIGHLIGHTED)
Receive
Payload Data
Output
Interface
Block
Receive
Payload Data
Output
Interface
Block
Receive
DS3/E3
Framer
Block
Receive
DS3/E3
Framer
Block
Receive
DS3/E3
LIU Block
Receive
DS3/E3
LIU Block
RxSer
RxNib[3:0]
RxClk
RRING
RTIP
Receive
Overhead Data
Output Interface
Block
Receive
Overhead Data
Output Interface
Block
RxOHClk
RxOHInd
RxOH
RxOHEnable
RxOHFrame
RxNibClk
RxFrame
Rx LAPD
Controller
Block
Rx LAPD
Controller
Block
From Microprocessor
Interface Block
Rx LAPD
Buffer
(90 Bytes)
Rx LAPD
Buffer
(90 Bytes)
Rx FEAC
Processor
Block
Rx FEAC
Processor
Block