XRT79L71IB datasheet(74/109 Pages) EXAR

74 / 109 page

XRT79L71

1-CHANNEL DS3/E3 ATM UNI/PPP/CLEAR-CHANNEL FRAMER IC - HARDWARE

REV. 1.0.0

comes with a LAPD Controller/Transmitter (not to be confused with the Transmit High-Speed HDLC Controller)

and 90 bytes of on-chip RAM (for storage of outbound PMDL Messages) prior to transmission.

The Transmit DS3/E3 Framer Block

The purpose of the Transmit DS3/E3 Framer block is to perform the following functions.

• To accept PPP packet and Flag Sequence octets from the Transmit PPP Packet Processor block and to map

all of this data into the payload bits within each outbound DS3 or E3 frame.

• To transmit the resulting framed DS3 or E3 data-stream to the Transmit DS3/E3 LIU Block. In this case, the

user can also configure the Transmit DS3/E3 Framer block to do the following.

a. Transmit an AIS Pattern (upon software command)

b. Transmit a DS3 Idle Pattern (upon software command)

c. Automatically transmit the FERF/RDI whenever the Receive DS3/E3 Framer block (within the very same

XRT79L71) declares the LOS, LOF/OOF or AIS defect conditions.

d. Automatically transmit the FEBE/REI indicator whenever the Receive DS3/E3 Framer block detects CP-

bit or Framing bit errors within the incoming DS3 data-stream (for DS3, C-bit Parity Applications only)

e. Automatically transmit the FEBE/REI indicator whenever the Receive DS3/E3 Framer block detects BIP-

8 errors within the incoming E3 data-stream (for E3, ITU-T G.832 Applications).

The Transmit DS3/E3 LIU Block

The purpose of the Transmit DS3/E3 LIU Block is to accept the outbound DS3/E3 data-stream from the

Transmit DS3/E3 Framer block and to perform the following functions on this data.

• Encode this data into the B3ZS Line Code (for DS3 Applications) or the HDB3 Line Code (for E3

Applications)

• To convert this outbound DS3 or E3 data-stream into a DS3/E3 line signal and transmit this signal to the

remote terminal equipment

• To generate and transmit DS3 pulses that comply with the Isolated Pulse Template requirements per

Bellcore GR-499-CORE

• To generate and transmit E3 pulses that comply with the ITU-T G.703 Pulse Template requirements for E3

Applications.

The Receive DS3/E3 LIU Block

The purpose of the Receive DS3/E3 LIU Block is to receive a DS3/E3 line signal from the remote terminal

equipment, and perform the following operations on this incoming line signal.

• 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).

The Receive DS3/E3 Framer Block

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