Rainbow Electronics DS3170 - Manual (Page 79)

DS3170 DS3/E3 Single-Chip Transceiver
79 of 233
9.6 DS3/E3 Framer / Formatter
9.6.1 General Description
The Receive DS3/E3 Framer receives a unipolar DS3/E3 signal, determines frame alignment and extracts the
DS3/E3 overhead in the receive direction. The Transmit DS3/E3 Formatter receives a DS3/E3 payload, generates
framing, inserts DS3/E3 overhead, and outputs a unipolar DS3/E3 signal in the transmit direction.
The Receive DS3/E3 Framer receives a DS3/E3 signal from the Receive LIU or RDAT (or RPOS and RNEG),
determines the frame alignment, extracts the DS3/E3 overhead, and outputs the payload with frame and overhead
The Transmit DS3/E3 Formatter receives a DS3/E3 payload on TSER, generates a DS3/E3 frame, optionally
inserts DS3/E3 overhead, and transmits the DS3/E3 signal.
Refer to Figure 9-12 for the location of the DS3/E3 Framer/Formatter blocks in the DS3170.
Figure 9-12. Framer Detailed Block Diagram
DS3/E3
Transmit
LIU
IEEE P1149.1
JTAG Test
Access Port
Microprocessor
Interface
HDLC FEAC
LL
B
DL
B
DS3 / E3
Transmit
Formatter
DS3 / E3
Receive
Framer
Trail
Trace
Buffer
DS3/E3
Receive
LIU
TAIS
TUA1
Clock Rate
Adapter
TX BERT
RX BERT
PL
B
AL
B
UA1
GEN
B3ZS/
HDB3
Encoder
B3ZS/
HDB3
Decoder
9.6.2 Features
9.6.2.1 Transmit Formatter
· Programmable DS3 or E3 formatter – Accepts a DS3 (M23 or C-bit) or E3 (G.751 or G.832) signal and
performs DS3/E3 overhead generation.
· Arbitrary framing format support – Generates a signal with an arbitrary framing format. The line
overhead/stuff periods are added into the data stream using an overhead mask signal.
· Generates alarms and errors – DS3 alarm conditions (AIS, RDI, and Idle) and errors (framing, parity, and
FEBE), or E3 alarm conditions (AIS and RDI/RAI) and errors (framing, parity, and REI) can be inserted into the
outgoing data stream.
· Externally controlled serial DS3/E3 overhead insertion port – Can insert all DS3 or E3 overhead via a
serial interface. DS3/E3 overhead insertion is fully controlled via the serial overhead interface.
· HDLC overhead insertion – An HDLC channel can be inserted into the DS3 or E3 data stream.
· FEAC insertion – A FEAC channel can be inserted into the DS3 or E3 data stream.
· Trail Trace insertion – Inputs and inserts the G.832 E3 TR byte.
9.6.2.2 Receive
Framer
· Programmable DS3 or E3 framer – Accepts a DS3 (M23 or C-bit) or E3 (G.751 or G.832) signal and performs
DS3/E3 overhead termination.