2.0 Circuit Description
CX28394/28395/28398
2.2 Receiver
Quad/x16/Octal—T1/E1/J1 Framers
2.2 Receiver
The Receiver (RCVR) inputs single rail NRZ data or decodes positive and
negative rail NRZ data into single rail NRZ data. The RCVR, illustrated in
Figure 2-3, consists of the following elements: Receive Zero Code Suppression
(RZCS) Decoder, In-Band Loopback Code Detector, Error Counters, Error
Monitor, Alarm Monitor, Test Pattern Receiver, Receive Framer, External
Receive Data Link, and Receive Data Links.
Figure 2-3. RCVR Diagram
MPU
Registers
DLINK1
DLINK2
MOP
External DLINK
PRBS/Inband LB
Sa-Byte
RNRZI
MOP/BOP
RPDV Monitor
RPOSI
RNEGI
RZCS
Decoder
RNRZ
Error Monitor
Error Counters
Alarm Monitor
Receive Framer
Receiver Timebase
To RSB
Line
Loopback
Framer
Loopback
RCKI
2.2.1 ZCS Decoder
The Receive Zero Code Suppression (RZCS) decoder is applicable only to the
CX28394 and CX28398. The decoder decodes the dual rail data (bipolar) into
single rail data (unipolar). The Receive AMI bit (RAMI) in the Receiver
Configuration register [RCR0; addr 040] controls whether the received signal is
B8ZS/HDB3 decoded, depending on T1/E1N [addr 001] line rate selection, or if
the RZCS decoder is bypassed. If the line code is unknown, the ZCSUB bit in
Receive Line Code Status [RSTAT; addr 021] indicates the RPOSI/RNEGI input
received one or more B8ZS/HDB3 substitution patterns. If the line code is
B8ZS/HDB3-encoded, the RZCS bit in RCR0 should be set to keep the LCV
counter from counting BPVs that are part of the B8ZS/HDB3 code.
2-4
Conexant
100054E
CONEXANT [ CONEXANT SYSTEMS, INC ]
