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PRELIMINARY
XRT79L71
22
REV. P2.0.0
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
To decode this incoming signal from the B3ZS Line Code (for DS3 Applications) or from the HDB3 Line Code
(for E3 Applications) into a binary data-stream
To route this binary data-stream to the Receive DS3/E3 Framer block for further processing
To insure that the XRT79L71 meets all of the following Receive requirements.
a. The Receive Sensitivity requirements for DS3 Applications (e.g., able to receive a DSX-3 type of signal
through at least 450 feet of cable loss)
b. The Receive Sensitivity requirements for E3 Applications (e.g., able to receive a E3 siganl over 12dB of
cable loss)
c. To comply with the Category I and II Jitter Tolerance Requirements per Bellcore GR-499-CorE (for DS3
Applications)
d. To comply with the Jitter Tolerance Requirements per ITU-T G.823 (for E3 Applications)
e. To comply with the Interference Margin Requirements of 20dB, per ITU-T G.703 (for E3 Applications).
1.4.11
The Receive DS3/E3 Framer Block
The purpose of the Receive DS3/E3 Framer block is to acquire and maintain Frame Synchronization with the
incoming DS3/E3 data-stream that it receives from the Receive DS3/E3 LIU Block. As the Receive DS3/E3
Framer block performs this task, it will also do the following.
It will declare and clear the LOS defect condition
It will declare and clear the LOF/OOF defect condition
It will declare and clear the AIS defect condition
It will declare and clear the FERF/RDI defect condition
It will detect and flag the occurrence of P-bit, CP-bit and Framing bit errors (DS3 Applications)
It will detect and flag the occurrence of BIP-8 Errors (E3, ITU-T G.832 Applications)
It will detect and flag the occurrence of BIP-4 Errors (E3, ITU-T G.751 Applications)
It will detect and flag the occurrences of FEBE/REI Events
It will detect and flag any occurrences of LCVs (Line Code Violations) and EXZs (Excessive Zero) events
within the incoming DS3/E3 line signal
It will extract the payload bits (out from each incoming DS3 or E3 frame) and it will route this data to the
Receive PPP Packet Processor block for further processing.
1.4.12
The Receive LAPD Controller Block
The purpose of the Receive LAPD Controller block is to permit the user to receive LAPD/PMDL (Path
Maintenance Data Link) Messages from the remote terminal equipment. The Receive LAPD Controller block
comes with a Receive LAPD Controller (not to be confused with the Receive High-Speed HDLC Controller
block) and 90 bytes of on-chip RAM (for storage of inbound PMDL Messages) after reception.
1.4.13
The Receive SSM Controller Block (E3, ITU-T G.832 Applications Only)
The purpose of the Receive SSM Controller block is to permit a given terminal equipment to receive (and
extract out) the SSM (Synchronization Status Message) from the remote terminal equipment, via the MA byte,
within each inbound E3, ITU-T G.832 frame.
The Receive SSM Controller block will also alert the
Microprocessor (by generating an interrupt) anytime it detects a change in the incoming SSM value.
1.4.14
The Receive Trail-Trace Message Controller Block (E3, ITU-T G.832 Applications Only)
The purpose of the Receive Trail-Trace Message Controller Block is to permit a given terminal equipment to
receive (and extract out) the Trail-Trace Message from the remote terminal equipment, via the TR byte, within
each inbound E3, ITU-T G.832 frame. The Receive Trail-Trace Message Controller block will also alert the
Microprocessor (by generating an interrupt) anytime it detects a change in the incoming Trail-Trace Message.