XRT79L71_07 Datasheet, PDF (61/109 Pages) Exar Corporation – 1-CHANNEL DS3/E3 ATM UNI/PPP/CLEAR-CHANNEL FRAMER IC - HARDWARE

XRT79L71
REV. 1.0.0
1-CHANNEL DS3/E3 ATM UNI/PPP/CLEAR-CHANNEL FRAMER IC - HARDWARE
The Transmit Payload Data Input Interface Block
The purpose of the Transmit Payload Data Input Interface block is to accept outbound payload data either via a
Serial or Nibble-Parallel interface, and to route this data to the Transmit DS3/E3 Framer block (where this data
will ultimately be mapped into the payload bit-positions within each outbound DS3/E3 frame).
The Transmit Overhead Data Input Interface Block
The purpose of the Transmit Overhead Data Input Interface block is to permit the user to externally insert his/
her own value for overhead bits into the outbound DS3/E3 data-stream.
NOTE: This particular feature is very valuable in those applications in which the XRT79L71 is processing a Channelized
DS3 signal that is of the M23-framing format (where it is imperative to preserve the contents of the C-bits within the
DS3 data-stream).
The Transmit LAPD Controller Block
The purpose of the Transmit LAPD Controller block is to permit the user to transmit LAPD/PMDL (Path
Maintenance Data Link) Messages to the remote terminal equipment. The Transmit LAPD Controller block
comes with a LAPD Controller/Transmitter and 90 bytes of on-chip RAM (for storage of outbound PMDL
Messages), prior to transmission.
The Transmit FEAC Controller Block (for DS3, C-Bit Parity Applications only)
The purpose of the Transmit FEAC Controller block is to permit the user to transmit FEAC (Far-End Alarm &
Control) Messages to the remote terminal equipment.
NOTE: The Transmit FEAC Controller Block is only active if the XRT79L71 is configured to operate in the DS3, C-bit Parity
Framing format.
The Transmit Trail-Trace Message Controller Block
The Transmit SSM Controller Block
The Transmit DS3/E3 Framer Block
The purpose of the Transmit DS3/E3 Framer block is to accept data from the Transmit Payload Data Input
Interface block, and Transmit Overhead Data Input Interface, the Transmit LAPD Controller and the Transmit
FEAC Controller block and to construct a DS3/E3 data-stream for transmission to the remote terminal
equipment. Additionally, the Transmit DS3/E3 Framer block can be configured to do all of the following.
• To transmit the AIS Indicator (upon Software Control)
• To automatically transmit the FERF/RDI Indicator (in response to the Receive DS3/E3 Framer block declare
the LOS, LOF/OOF or AIS defect condition).
• To transmit the FERF/RDI indicator (upon Software Control)
• To automatically transmit the FEBE/REI Indicator (in response to the Receive DS3/E3 Framer block
detecting Framing bit or CP-bit errors - DS3, C-bit Parity Applications).
• To automatically transmit the FEBE/REI Indicator (in response to the Receive DS3/E3 Framer block
detecting BIP-8 Error - E3, ITU-T G.832 Applications).
• To transmit the FEBE/REI indicator (upon Software Control).
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 all of the following operations on this signal.
• To encode into the B3ZS Line Code (for DS3 Applications) or the HDB3 Line Code (for E3 Applications)
• To convert this outbound DS3 or E3 data into a DS3/E3 line signal and transmit this signal to the remote
terminal equipment.
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